1
Q
What is the primary diagnostic test for both pulmonary and extrapulmonary TB in adults and children according to the Philippine NTP MOP?
A
A rapid diagnostic test (RDT), such as Xpert MTB/RIF.
2
Q
According to the Philippine NTP MOP, how is a ‘new’ TB case defined for the purpose of disease registration?
A
A patient who has never had treatment for TB or who has taken anti-TB drugs for less than one month.
3
Q
What is the term for a patient who was previously treated for TB, declared cured or treatment completed, but is presently diagnosed with active TB disease?
A
Relapse.
4
Q
The standard treatment regimen for new, bacteriologically confirmed pulmonary TB (BCTB) cases in adults consists of an intensive phase of _____ and a continuation phase of _____.
A
2 months of RHZE; 4 months of RH.
5
Q
If a pulmonary TB patient on a DS-TB regimen has a positive smear microscopy result at the end of the intensive phase (2nd month), what is the immediate next step?
A
Request an Xpert MTB/RIF test and proceed to the continuation phase while awaiting results.
6
Q
According to the Philippine NTP MOP, a DS-TB patient whose treatment was interrupted for at least two consecutive months is assigned what treatment outcome?
A
Lost to follow-up (LTFU).
7
Q
The two key mycobacterial proteins secreted by the ESX-1 type VII secretion system, which are important for virulence, are ESAT-6 and _____.
A
CFP-10.
8
Q
Which cytokine is considered essential for immunity to tuberculosis in humans, as evidenced by the high risk of TB in patients treated with agents that block its activity?
A
Tumor Necrosis Factor (TNF).
9
Q
What is the classic radiographic finding in primary TB, resulting from recent infection?
A
A middle or lower lung zone opacity, often associated with ipsilateral hilar adenopathy.
10
Q
What is the common radiographic presentation of reactivation TB?
A
Involvement of the upper lobes of one or both lungs, with cavitation being common.
11
Q
The Xpert MTB/RIF assay detects M. tuberculosis complex and rifampin resistance by amplifying a sequence of which gene?
A
The rpoB gene.
12
Q
Isoniazid (INH) is a prodrug that requires activation by which mycobacterial enzyme to exert its bactericidal activity?
A
KatG.
13
Q
What is the mechanism of action of pyrazinamide (PZA)?
A
It is a prodrug activated to pyrazinoic acid (POA), which is thought to inhibit fatty acid synthesis and disrupt membrane transport.
14
Q
For a patient with culture-negative pulmonary TB who shows clinical and radiographic improvement after 2 months of intensive therapy, what is the recommended total duration of treatment?
A
A total of 4 months (2 months intensive phase + 2 months continuation phase).
15
Q
In treating tuberculous meningitis, what is the recommended total duration of therapy?
A
9 to 12 months.
16
Q
What class of antiretroviral drugs is most significantly affected by rifampin due to potent induction of CYP3A4 enzymes?
A
Protease inhibitors.
17
Q
A single new drug should never be added to a failing TB regimen because it can lead to _____.
A
amplification of drug resistance.
18
Q
What is the primary reason Nontuberculous Mycobacteria (NTM) are difficult to treat compared to M. tuberculosis?
A
They have high levels of intrinsic resistance to many antimicrobial drugs.
19
Q
For Mycobacterium avium complex (MAC) pulmonary disease, clinical response to treatment correlates primarily with in vitro susceptibility to which two classes of drugs?
A
Macrolides (clarithromycin, azithromycin) and amikacin.
20
Q
The Philippine NTP MOP defines a ‘presumptive TB’ case as a patient with any of the cardinal signs (cough, fever, weight loss, night sweats) lasting for how long?
A
Two weeks or more (≥2 weeks).
21
Q
What is the only contraindication to collecting sputum for bacteriological diagnosis of TB, according to the NTP MOP?
A
Massive hemoptysis.
22
Q
What is the interpretation of an Xpert MTB/RIF result of ‘TI’?
A
MTB detected, rifampicin resistance indeterminate.
23
Q
In the Philippine MOP, what is the term for TB resistant to more than one first-line anti-TB drug, other than both isoniazid and rifampicin?
A
Polydrug-resistant TB.
24
Q
If a new TB case (low risk for MDR-TB) has an initial Xpert result of ‘MTB detected, RIF resistance detected’, what is the recommended next step before starting a DR-TB regimen?
A
Recollect a fresh sputum sample to repeat the Xpert MTB/RIF test and follow the second result for the treatment decision.
25
The treatment outcome 'Treatment Failed' for DS-TB is assigned if a patient's sputum smear or culture is positive at what point during treatment?
At five months or later.
26
What is the target treatment success rate for DR-TB patients according to the Philippine NTP MOP?
Greater than 85% (> 85%).
27
The Standard Short All Oral Regimen (SSOR) for DR-TB in the Philippines includes which four drugs in its initial 4-6 month phase?
Bedaquiline, Pretomanid, Linezolid, and Moxifloxacin (BPaLM).
28
What is the primary purpose of active drug safety monitoring and management (aDSM) in DR-TB treatment?
To ensure early detection and proper management of adverse drug reactions, particularly serious adverse events.
29
According to the Philippine MOP, TB preventive treatment (TPT) is currently not recommended for which group of contacts?
Contacts of MDR-TB and RR-TB cases.
30
Which TPT regimen is currently available under the Philippine program, as per the 6th MOP?
6 months of daily Isoniazid (6H).
31
The mycobacterial lipid _____ works in concert with the ESX-1 secretion system to mediate phagosomal damage.
phthiocerol dimycocerosate (PDIM).
32
In TB pathogenesis, production of which cytokine family, triggered by the cGAS-STING pathway, is associated with a detrimental host response and correlates with disease extent?
Type I Interferons (IFN-α and/or IFN-β).
33
How does *M. tuberculosis* evade CD4 T cell recognition via its ESX-3 effector protein, EsxH?
EsxH interferes with MHC/HLA class II antigen presentation by limiting antigen processing.
34
A diagnosis of TB can be made by an appropriate response to antituberculosis therapy, which should typically be seen within what timeframe of starting treatment?
Within 2 months.
35
Which diagnostic method is considered the current gold standard for TB diagnosis and can detect as few as 10 to 1000 viable mycobacteria/mL of sputum?
Culture in liquid media.
36
What is a major advantage of the Xpert MTB/RIF Ultra assay over the standard Xpert MTB/RIF assay?
It has a lower limit of detection (higher sensitivity), particularly in smear-negative, culture-positive TB cases.
37
What is a significant disadvantage of the Xpert MTB/RIF Ultra assay, especially in individuals with a history of TB?
It has lower specificity, as its increased sensitivity can detect non-viable bacilli from a previous infection, leading to false-positive results.
38
What is the most frequent serious adverse reaction to first-line anti-TB drugs?
Drug-induced hepatitis (hepatotoxicity).
39
According to treatment guidelines, hepatotoxic anti-TB drugs must be stopped if a patient's ALT levels are more than _____ times the upper limit of normal (ULN) with or without symptoms.
five.
40
A patient taking ethambutol should undergo monthly monitoring of visual acuity and _____.
color discrimination.
41
In a patient co-infected with TB and HIV, when should antiretroviral therapy (ART) be initiated relative to the start of TB treatment for patients with a CD4 count <50 cells/mm³?
Within 2 weeks of starting TB treatment.
42
Linezolid, a key drug for DR-TB, has a risk of causing which two major dose- and duration-dependent toxicities?
Myelosuppression (anemia, thrombocytopenia) and peripheral/optic neuropathy.
43
For treatment-refractory *Mycobacterium avium* complex (MAC) pulmonary disease, what inhaled medication should be added to the guideline-based therapy?
Amikacin liposome inhalation suspension (ALIS).
44
What is the recommended treatment regimen for drug-susceptible *Mycobacterium kansasii* pulmonary disease?
A three-drug regimen of rifampin, ethambutol, and a macrolide (or isoniazid) for at least 12 months.
| Isoniazid 600 mg/day, Rifampicin 300mg/day, EMB 15mg/kg.day
45
The presence of a functional _____ gene in *Mycobacterium abscessus* confers inducible resistance to macrolides.
erythromycin resistance methylase (erm).
46
In the GRADE approach, what factor is assessed by the I² statistic, with a value ≥60% often indicating a reason to downgrade the quality of evidence?
Inconsistency or heterogeneity of results across studies.
47
The Bayes nomogram is a tool used for estimating what value in diagnostic testing?
Post-test probability of disease.
48
What is the recommended follow-up schedule for household contacts of DS-TB cases after initial screening?
Symptom screening every six months and chest X-ray screening annually for two years.
49
According to the Philippine NTP MOP, what is the desired turnaround time (TAT) from collection of the first sputum sample to initiation of TB treatment?
Five working days.
50
For which groups is Tuberculin Skin Test (TST) or Interferon-Gamma Release Assay (IGRA) NOT required prior to initiating TB preventive treatment in the Philippines?
PLHIV, child household contacts <5 years old of bacteriologically confirmed PTB, and contacts ≥5 years old with other TB risk factors.
51
What is the mechanism of action of fluoroquinolones like levofloxacin and moxifloxacin against *M. tuberculosis*?
They inhibit bacterial DNA gyrase, preventing DNA synthesis.
52
What is the mechanism of action of bedaquiline?
It inhibits mycobacterial ATP synthase.
53
When treating a patient co-infected with TB/HIV, why is rifabutin often preferred over rifampin?
Rifabutin is a less potent inducer of CYP3A4 enzymes, resulting in fewer and less severe drug-drug interactions with antiretrovirals, particularly protease inhibitors.
54
The treatment of bone and joint TB typically requires a longer duration of therapy, ranging from _____ to _____ months.
6 to 9 months.
## Footnote
murray, but in NTP 12months
55
Why should macrolides never be used as monotherapy for the treatment of *Mycobacterium avium* complex (MAC) disease?
Monotherapy rapidly leads to the development of high-level macrolide resistance, which is the cornerstone of effective therapy.
56
What is the purpose of the Microscopic Observation of Drug Susceptibility (MODS) assay?
It is a culture-based method that simultaneously detects *M. tuberculosis* complex growth and determines susceptibility to rifampin and isoniazid.
57
In the context of the Philippine CPG, what action is recommended for training programs found to have 70% compliance or lower with the TB guidelines?
They will undergo re-orientation by one of the main professional societies (PhilCAT, PSMID, PCCP).
58
In interpreting evidence on diagnostic tests, what does 'sensitivity' refer to?
The proportion of persons with the disease who correctly have a positive test.
59
On a forest plot summarizing multiple studies, what does the diamond represent?
The summary effect (pooled estimate) of all studies, where the center is the point estimate and the horizontal tips are the 95% confidence interval.
60
The 2016 National TB Prevalence Survey in the Philippines showed that screening for TB using symptoms alone would miss what proportion of bacteriologically confirmed cases?
One-third to two-thirds of cases.
61
For health-care workers in the Philippines, how often should follow-up screening for TB symptoms be conducted?
Biannually (every six months).
62
According to the NTP MOP, who should provide treatment support to ensure adherence in a patient-centered approach?
Health workers, community volunteers, or family members.
63
What is the recommended management for peripheral neuropathy (burning sensation in the feet) caused by isoniazid?
Give pyridoxine (Vitamin B6) 50–100 mg daily.
64
Xpert MTB/RIF is not used for treatment monitoring because it cannot determine MTB _____.
viability (it may detect DNA from nonviable or dead bacilli).
65
What baseline test is specifically required for patients starting a DR-TB regimen containing cycloserine, with monthly follow-ups recommended?
Mental health screening.
66
What baseline test is required for patients starting a DR-TB regimen containing bedaquiline, delamanid, clofazimine, or moxifloxacin, with monthly monitoring?
Electrocardiogram (ECG) to monitor the QTc interval.
67
In the Philippine NTP, what is the official system for recording and reporting TB cases?
The Integrated Tuberculosis Information System (ITIS).
68
What Republic Act governs data privacy for patient information collected by the NTP in the Philippines?
Republic Act 10173 (Data Privacy Act of 2012).
69
In which situation is a Tuberculin Skin Test (TST) preferred over an Interferon-Gamma Release Assay (IGRA) for LTBI screening?
In children younger than 5 years.
70
In which situation is an Interferon-Gamma Release Assay (IGRA) preferred over a Tuberculin Skin Test (TST) for LTBI screening?
In individuals with a history of BCG vaccination or those at high risk of being lost to follow-up.
71
What is 'boosting' in the context of TST?
A phenomenon where a second TST administered weeks to a year after the first TST elicits a positive reaction, representing a boosted memory of a distant infection, not a new infection.
72
How does *M. tuberculosis* primarily evade the host innate immune system after being phagocytosed?
It inhibits phagosome maturation and acidification, creating a niche for survival and replication within macrophages.
73
Patients with genetic mutations in the receptor for which cytokine are especially susceptible to severe and disseminated mycobacterial diseases, including TB?
Interferon-gamma
74
With advanced HIV and significant CD4 T-cell deficiency, the radiographic findings of TB become 'atypical' and are characterized by what features?
Lower lung zone or diffuse opacities and intrathoracic adenopathy, with cavitation being uncommon.
75
What is the primary mechanism of rifampin's bactericidal activity?
It inhibits bacterial DNA-dependent RNA polymerase.
76
Why should ethambutol be used with caution in patients with significant renal impairment?
Ethambutol is primarily cleared by the kidneys, and impaired clearance increases the risk of optic neuritis.
77
What is immune reconstitution inflammatory syndrome (IRIS) in the context of TB-HIV co-infection?
A paradoxical worsening of TB symptoms and signs after initiating antiretroviral therapy (ART), caused by the recovering immune system mounting a vigorous inflammatory response to TB antigens.
78
When constructing an empirical MDR-TB regimen, what is the minimum number of likely effective drugs that should be included in the intensive phase for the highest chance of success?
Five effective drugs.
79
The diagnosis of NTM pulmonary disease, unlike TB, usually requires what microbiologic evidence?
Repeated isolation of the same NTM species from multiple sputum specimens or a single positive culture from a bronchoscopic specimen.
80
Which rapidly growing mycobacterium is notoriously difficult to treat and requires subspecies identification to predict macrolide susceptibility?
*Mycobacterium abscessus*.
81
For a patient on a DS-TB regimen who interrupts treatment for more than 14 days during the intensive phase, what is the recommended action?
Restart treatment from the beginning.
| this is from Murray. But in NTP,
82
Which first-line anti-TB drug is known to cause orange discoloration of urine and other body fluids?
Rifampicin (Rifampin).
83
In DR-TB treatment, baseline and monthly monitoring of which electrolyte is important when using amikacin or streptomycin?
Potassium (K).
84
In the treatment of TB pericarditis, what adjunctive therapy is recommended to reduce the risk of constriction and mortality?
Corticosteroids
selective use of corticosteroids in patients at the highest risk for inflammatory complications, including those with:
* Large pericardial effusions.
* High levels of inflammatory cells or markers in the pericardial fluid.
* Clinical signs of constriction
85
What is the definition of extensively drug-resistant TB (XDR-TB)?
TB that is resistant to isoniazid and rifampin (MDR-TB), plus resistance to any fluoroquinolone and at least one second-line injectable drug.
86
What is the primary transmission route for Nontuberculous Mycobacteria (NTM)?
Exposure to environmental sources, such as soil and water; human-to-human transmission is not considered a significant route.
87
What structural feature of mycobacteria is responsible for their acid-fastness property?
A thick, lipid-rich cell envelope composed of mycolic acids.
88
In patients with tuberculous pleuritis, the pleural fluid is typically a _____ exudate.
lymphocytic.
89
What is the term for the gross appearance of disseminated TB lesions, which resemble 1- to 2-mm yellowish nodules similar to millet seeds?
Miliary.
90
What is the purpose of therapeutic drug monitoring (TDM) in TB treatment?
To ensure adequate drug exposure by measuring serum drug concentrations, which is particularly useful in patients at risk for malabsorption or altered pharmacokinetics.
91
Cycloserine, a second-line anti-TB drug, is known to cause adverse _____ effects, and co-administration of pyridoxine is recommended.
psychiatric.
92
What is the recommended duration of treatment for nodular bronchiectatic MAC disease?
At least 12 months beyond the date of sputum culture conversion.
93
According to the Philippine CPG, what is the role of the Steering Committee in the guideline development process?
To oversee the process by setting objectives, scope, target audience, and clinical questions, and to form the working groups.
94
If a patient on a DS-TB regimen is found to have rifampicin resistance on an Xpert test at the 2nd month follow-up, what is the treatment outcome for the initial DS-TB regimen?
Treatment failed.
95
What is the name of the Philippine national strategic plan for TB elimination mentioned in the MOP?
Philippine Strategic TB Elimination Plan: Phase 1 (PhilSTEP1).
96
What is the minimum volume of sputum required for an Xpert MTB/RIF test according to the Philippine NTP MOP?
1 ml.
97
If a patient on a DS-TB regimen has a positive sputum smear after the fifth month, what is the next action?
Stop treatment, declare as treatment failure, perform an Xpert MTB/RIF test, and refer to a PMDT treatment center.
98
In the Philippine MOP, what committee must be consulted for cases requiring individualized treatment regimens (ITR) or off-label use of anti-TB drugs?
The TB Medical Advisory Committee (TB MAC).
99
What two baseline vision tests are required before starting a DR-TB regimen?
Visual acuity and color vision test.
100
A serious adverse event (SAE) is defined as any untoward medical occurrence that results in death, is life-threatening, requires hospitalization, results in persistent disability, is a congenital anomaly, or requires _____.
an intervention to prevent a serious outcome.
101
In the post-treatment follow-up for DR-TB, what is the term for recurrent TB disease in a successfully treated individual who becomes culture-positive within 6 to 12 months after cure?
Relapse.
102
In the Philippine MOP, what is the recommended TPT regimen for a 7-year-old child who is a household contact of a bacteriologically confirmed PTB case but has no other risk factors, and has a positive TST?
Six months of daily isoniazid (6H).
103
What is the main reason that dual TST and IGRA testing might be considered for an individual with a high risk for TB progression but a negative initial test?
To increase diagnostic sensitivity when sensitivity is prioritized over specificity.
104
What is the primary cellular niche for *M. tuberculosis* replication in the host lung before the onset of adaptive immunity?
Alveolar macrophages.
105
What is the function of the inflammasome during *M. tuberculosis* infection?
It is a cytosolic immune sensor that processes pro-IL-1β and pro-IL-18 into their mature forms and can trigger pyroptosis.
106
In a patient with suspected TB who cannot produce sputum, what is the most useful and least uncomfortable procedure for obtaining a specimen?
Sputum induction using inhaled hypertonic saline.
107
The WHO strongly recommends against the use of which type of tests for the diagnosis of pulmonary and extrapulmonary TB due to their high variability and poor performance?
Serologic (antibody-based) tests.
108
What is the standard recommended treatment duration for uncomplicated drug-susceptible pulmonary TB?
Six months.
109
What are the four first-line drugs used in the standard intensive phase treatment for drug-susceptible TB?
Isoniazid (H), Rifampin (R), Pyrazinamide (Z), and Ethambutol (E).
110
When co-administering rifampin with dolutegravir for TB/HIV treatment, what adjustment must be made to the dolutegravir dose?
The dose of dolutegravir must be increased to 50 mg twice daily.
111
What is the most common NTM species to cause pulmonary disease in people with cystic fibrosis in the United States?
*Mycobacterium avium* complex (MAC).
112
What is the term for an NTM species that is usually considered a respiratory contaminant and is frequently isolated from tap water, often causing pseudo-outbreaks?
*Mycobacterium gordonae*.
113
What is the primary purpose of Line Probe Assays (LPA) in the management of TB?
To rapidly detect resistance to key first-line (isoniazid, rifampin) and second-line (fluoroquinolones, injectables) anti-TB drugs.
114
According to the Philippine MOP, all TB patients aged _____ years and above shall be screened for diabetes.
25
115
What is the definition of a 'Treatment after failure' case in the context of retreatment TB?
A patient who was previously treated for TB but failed the most recent course.
116
For a patient with tuberculous lymphadenitis, what is the recommended treatment regimen and duration?
The standard 6-month regimen for pulmonary TB (2RHZE/4RH).
117
The drug pretomanid is a nitroimidazole that works by inhibiting _____ synthesis and is bactericidal against both actively and sporadically multiplying bacilli.
mycolic acid.
118
In diagnosing pleural TB, which procedure provides a higher diagnostic yield than culture of pleural fluid alone?
A closed-needle biopsy of the pleura for histologic examination and culture.
119
The World Health Organization (WHO) End TB Strategy aims to reduce TB deaths by what percentage by 2035?
0.95
120
What is the primary risk factor for the development of macrolide-resistant MAC disease?
Previous macrolide monotherapy or treatment with an inadequate companion drug regimen.
121
What radiographic finding, though not definitive, is more suggestive of active TB compared to old, healed TB?
The presence of a cavity.
122
In the context of the Philippine CPGs, what is the minimum percent compliance to the guidelines required for training institutions to avoid re-orientation?
Greater than 70%.
123
What is the main difference in interpreting the 95% CI for inconclusive vs. equivalent results in treatment effectiveness studies?
In both cases the CI straddles the point of no effect, but for equivalence, both ends of the CI are clinically insignificant or ignorable.
124
According to the Philippine MOP, screening for PTB in targeted communities and congregate settings should be done annually using what method?
Chest X-ray.
125
If a child under 15 years old cannot expectorate sputum, what are two alternative specimen collection methods that may be performed?
Nasopharyngeal aspirate or gastric lavage.
126
What is the recommended treatment regimen for isoniazid-monoresistant TB?
A 6-month regimen of rifampin, ethambutol, and pyrazinamide (with levofloxacin sometimes added).
127
How does the host repair minor phagosomal damage induced by *M. tuberculosis*, and how does the bacterium counteract this?
The host uses the ESCRT system for repair, which is interfered with by the mycobacterial EsxH protein.
128
Why is drug susceptibility testing recommended for all initial *M. tuberculosis* isolates?
To guide appropriate therapy and identify drug resistance early, preventing treatment failure and further transmission of resistant strains.
129
For patients with cavitary MAC pulmonary disease, what modification to the standard three-drug oral regimen is recommended?
The regimen should be administered daily (instead of three times weekly) and a parenteral aminoglycoside (amikacin or streptomycin) should be considered for the first 2-3 months.
130
If a patient on a standard DS-TB regimen experiences a treatment interruption of 35 days during the continuation phase, what is the appropriate management?
Perform a sputum smear microscopy; if negative, continue treatment and prolong it to compensate for the missed doses.
131
What is the role of clofazimine in DR-TB and NTM treatment?
It is an oral agent used as part of a multi-drug regimen, with activity against *M. tuberculosis* and many NTM species, including MAC.
132
What is the primary indicator used to interpret a TST reaction?
The diameter of induration (not erythema), measured in millimeters.
133
The _____ mycobacteria are defined by their ability to grow in subculture in less than 7 days.
rapidly growing.
134
What is the purpose of decontaminating sputum specimens before mycobacterial culture on solid media?
To decrease the overgrowth of more rapidly growing oral flora (other bacteria and fungi) that would otherwise contaminate the culture.
135
An asymptomatic increase in ALT observed in patients starting a standard four-drug TB regimen, which often resolves despite continuing treatment, is known as _____.
hepatic adaptation.
136
A patient taking rifampin and a protease inhibitor for HIV requires expert consultation because rifampin significantly _____ the levels of the protease inhibitor.
decreases.
137
What is the defining characteristic of rifampicin-resistant TB (RR-TB)?
Resistance to rifampicin detected by phenotypic or genotypic methods, with or without resistance to other anti-TB drugs.
138
If a patient on a DR-TB regimen containing Linezolid develops severe anemia, what is the likely cause and management?
The cause is likely Linezolid-induced myelosuppression; management may involve dose reduction or temporary/permanent discontinuation of the drug.
139
In cases of suspected active TB with negative microbiologic results, TST or IGRA can be used to guide decisions about what type of treatment?
Empirical treatment for active TB.
140
The risk of an individual with LTBI developing active TB disease is greatest within what time frame after initial infection?
Within the first 2 years.
141
What is the mechanism by which *M. tuberculosis* EsxH protein, secreted by the ESX-3 system, impedes host immunity?
It interferes with phagosome maturation and MHC class II antigen presentation.
142
A patient with suspected TB has negative sputum smears and a negative NAAT. Why can active TB not be definitively ruled out?
Current NAATs do not possess sufficient sensitivity to replace mycobacterial culture, and the patient may have paucibacillary disease.
143
What is the reference standard method for phenotypic drug susceptibility testing of *M. tuberculosis*?
The proportion method, performed in liquid media.
144
In a patient with renal insufficiency, which of the four first-line anti-TB drugs requires dose adjustment?
Ethambutol and Pyrazinamide.
145
In building an empirical MDR-TB regimen, what are the first three drugs (Group A) that should be included, in order of preference?
A later generation fluoroquinolone (levofloxacin or moxifloxacin), bedaquiline, and linezolid.
146
What is the most important predisposing risk factor for developing NTM pulmonary disease in an immunocompetent host?
Pre-existing chronic pulmonary disease, such as bronchiectasis or COPD.
147
What is the primary diagnostic challenge in distinguishing NTM infection or colonization from NTM disease?
The organisms are ubiquitous in the environment, so a single positive sputum culture may represent contamination or colonization rather than true disease.
148
What is the recommended total duration of treatment for DR-TB using a standard long all-oral regimen (SLOR)?
18 to 20 months.
149
The Philippine MOP classifies a presumptive TB case based on signs and symptoms or a chest X-ray, followed by diagnosis through _____ testing.
bacteriological.
150
What are the four conventional ways of determining the accuracy of a diagnostic test listed in the Philippine CPG?
Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).
151
In the Philippine MOP, what form is used to notify all diagnosed active TB cases?
Form 4a. TB Notification.
152
If a DR-TB patient on SSOR has a baseline LPA result showing resistance to fluoroquinolones, what is the recommended action?
Shift to the SLOR FQ-R (Standard Long All Oral Regimen for Fluoroquinolone Resistance) and restart the dose count.
153
According to the Philippine MOP, for whom is TST required before offering TPT?
Contacts ≥5 years of a BCTB index case with no other risk factors, and patients with specific conditions like silicosis or preparing for transplant.
154
What is the primary pathogenic role of Type I interferons during *M. tuberculosis* infection in mouse models?
They are detrimental, enhancing recruitment of permissive mononuclear cells and limiting expression of the protective cytokine IL-1β.
155
What is the main advantage of fluorescence microscopy over brightfield microscopy for AFB smears?
It has increased sensitivity and can be read much faster.
156
What is the definition of 'treatment completed' for a DR-TB patient on a longer regimen?
A patient who has completed treatment according to national policy without evidence of failure, but for whom bacteriologic results are missing or incomplete.
157
A 28-year-old HIV-positive patient presents with a 3-week history of fever, night sweats, and
weight loss. Chest X-ray shows bilateral lower lobe infiltrates without cavitation. Sputum AFB
smears are negative on three consecutive specimens. TST is non-reactive. Which combination of
factors BEST explains the atypical presentation?
A. Low CD4 count leading to atypical radiographic pattern
B. Drug-resistant tuberculosis causing negative AFB smears
C. Extrapulmonary tuberculosis predominance
D. Concurrent opportunistic infection masking TB
A
Atypical Radiographic Pattern: In patients with advanced HIV disease and CD4 T-cell deficiency, the radiographic findings of pulmonary TB become more "atypical". This means that cavitation is uncommon, and lower lung zone or diffuse opacities are frequent presentations. The presence of bilateral lower lobe infiltrates without cavitation aligns with this atypical presentation caused by severe immunosuppression
Immunosuppression associated with HIV infection leads to diminished delayed-type hypersensitivity reactions. HIV infection is noted as the strongest known risk factor for progression to active disease, and HIV-infected individuals with advanced immunosuppression (such as CD4 counts less than 200 cells/μL) have higher rates of false-negative TST results (anergy)
While the symptoms (fever, night sweats, weight loss) strongly suggest active TB, particularly in this high-risk population, the lack of positive sputum smears suggests a low bacillary load (paucibacillary disease). Extrapulmonary TB (EPTB), which is often paucibacillary and common in immunocompromised hosts, can contribute to systemic symptoms and negative sputum tests
158
32-year-old pregnant woman at 28 weeks gestation is diagnosed with pulmonary tuberculosis.
Culture reveals M. tuberculosis sensitive to all first-line drugs. She has no history of TB treatment. Which treatment regimen represents the MOST appropriate balance of maternal treatment efficacy and fetal safety?
A. Isoniazid, rifampin, ethambutol for 9 months
B. Isoniazid, rifampin, ethambutol, pyrazinamide for 6 months
C. Isoniazid, rifampin, pyrazinamide for 6 months
D. Delay treatment until after delivery, then standard 4-drug therapy
A
For pregnant women with active TB, untreated disease poses a far greater hazard to the woman and her fetus than does treatment. Therefore, delaying treatment is not advisable.
The core first-line drugs (Isoniazid, Rifampicin, and Ethambutol) are generally considered safe for use during pregnancy and breastfeeding. Antituberculosis drugs cross the placenta but do not appear to have teratogenic effects in humans.
However, the inclusion of Pyrazinamide (PZA) in the regimen for pregnant women is controversial, particularly based on guidance from the Centers for Disease Control and Prevention (CDC) in the United States, although the World Health Organization (WHO) recommends PZA as part of the standard treatment regimen.
To maximize fetal safety while maintaining efficacy, the most appropriate regimen involves excluding PZA and extending the duration of therapy:
* If the decision is made to exclude PZA from the regimen due to controversy and lack of data, a minimum of 9 months of isoniazid (INH), rifampin (RIF), and ethambutol (EMB) is required to achieve successful treatment outcomes.
* This regimen typically follows a pattern of 2 months of INH, RIF, and EMB, followed by 7 months of INH and RIF (or similar combination to complete 9 months total treatment), which provides the necessary duration to compensate for the exclusion of PZA, a powerful sterilizing agent
159
A 55-year-old patient with cavitary pulmonary TB shows clinical improvement after 2 months of
standard 4-drug therapy (RIPE). However, 2-month sputum culture remains positive with the
same drug-susceptible organism. The patient reports 95% medication adherence. Which factor
MOST likely explains the persistently positive culture and influences treatment modification?
Choose the best answer
Answer
A. Emerging drug resistance requiring immediate susceptibility testing
B. Malabsorption of medications necessitating therapeutic drug monitoring
C. Large bacterial burden in cavitary disease requiring extended intensive phase
D. Poor medication adherence despite patient's reported compliance
C
Studies indicate that patients with signs of more extensive disease (e.g., cavitation, or higher bacterial burdens) have an increased risk of relapse. The intensive phase of treatment aims to eliminate the actively multiplying bacteria, which are most abundant when the bacillary population is highest. Cavitary lesions present a high bacterial burden and a difficult environment for drug penetration.
The end-of-intensive-phase culture (at 2 months) status, particularly when combined with cavitary disease, is a critical predictor of treatment outcomes. For patients who have cavitation on the initial chest radiograph and a positive culture at completion of 2 months of therapy, the continuation phase is extended by an additional 3 months, resulting in 9 months of total therapy
160
A 65-year-old patient with chronic kidney disease (GFR 30 mL/min/1.73m²) is diagnosed with pulmonary tuberculosis. Culture shows pan-sensitive M. tuberculosis. Which modification to standard therapy BEST addresses the pharmacokinetic challenges while maintaining treatment efficacy?
A. Standard 4-drug therapy with 50% dose reduction for all medications
B. Isoniazid, rifampin, ethambutol daily; avoid pyrazinamide entirely
C. Standard doses of isoniazid and rifampin; reduce ethambutol dose and avoid
pyrazinamide
D. Three-times-weekly dosing of all four drugs at standard doses
C
Both INH and RIF are metabolized by the liver. Therefore, for patients with renal insufficiency, the sources state that conventional dosing of RIF and INH can be used
PZA is metabolized by the liver, but its metabolites may accumulate in patients with renal insufficiency. In cases of creatinine clearance less than 30 mL/min, the dose frequency should typically be reduced, such as changing to thrice weekly (tiw) dosing. Avoiding PZA entirely, as suggested in option C, is a cautious clinical strategy to minimize toxicity in compromised patients, though it necessitates extending the continuation phase of therapy to 7 months or more (9 months total)
Approximately 80% of EMB clearance is done by the kidneys, and it may accumulate in patients with renal insufficiency. For patients with severe renal impairment (CrCl <30 mL/min), guidelines recommend maintaining the total dosage but decreasing the frequency of administration (i.e., changing from daily to three times weekly) to avoid accumulation and toxicity, particularly optic neuritis. Therefore, the regimen must include an adjustment to EMB administration.
161
A 35-year-old patient with multi-drug resistant tuberculosis (MDR-TB) resistant to isoniazid and
rifampin shows poor clinical response after 3 months of treatment with ethambutol, pyrazinamide, levofloxacin, and amikacin. Additional susceptibility testing reveals resistance to fluoroquinolones. Which principle BEST guides the modification of the treatment regimen?
A. Add bedaquiline and maintain current regimen for synergistic effect
B. Replace levofloxacin with linezolid and add bedaquiline to achieve 4-5 effective drugs
C. Increase dosing frequency of current medications to overcome resistance
D. Add cycloserine and para-aminosalicylic acid while continuing levofloxacin
B
The core structure for treating FQ-R MDR-TB (Standard Long All Oral Regimen for FQ-R) typically includes Bedaquiline (Bdq) and Linezolid (Lzd) as crucial components.
Therefore, replacing the resistant drug (Lfx) and strengthening the overall regimen by introducing two potent new drugs (Lzd and Bdq) is the principle that guides the modification to ensure adequate treatment efficacy. Option A is incorrect because a single new drug should never be added to a
162
9. A 38-year-old patient with pulmonary TB develops severe hepatotoxicity (ALT >5x upper limit
normal) after 6 weeks of RIPE therapy. Liver biopsy shows drug-induced hepatitis. After hepatic
function normalizes, which re-challenge strategy BEST balances treatment efficacy with safety
monitoring?
Choose the best answer
Answer
A. Restart all four drugs simultaneously at reduced doses with frequent monitoring
B. Sequential reintroduction: rifampin first, then isoniazid, followed by ethambutol and
pyrazinamide
C. Use alternative regimen with fluoroquinolone, ethambutol, and aminoglycoside
D. Sequential reintroduction: isoniazid first, then rifampin, followed by ethambutol;
avoid pyrazinamide
RIF → INH → PZA/EMB
163
A 25-year-old recent immigrant presents with chronic cough, weight loss, and chest X-ray
showing bilateral upper lobe cavitation. Three sputum specimens are AFB-positive, but
molecular testing (GeneXpert) is negative for M. tuberculosis. Culture is pending. Which
differential diagnosis MOST likely explains this discordant result and influences immediate
management?
Choose the best answer
Answer
A. False-negative GeneXpert due to inhibitors in sputum specimens
B. Nontuberculous mycobacterial infection, likely M. avium complex
C. Drug-resistant M. tuberculosis with genetic mutations affecting PCR targets
D. Mixed infection with M. tuberculosis and nontuberculous mycobacteria
The differential diagnosis that MOST likely explains this discordant result and influences immediate management is B. Nontuberculous mycobacterial infection, likely M. avium complex.
This conclusion is based on the specific capabilities and findings of the diagnostic tests:
1. AFB Smear Positive: The positive acid-fast bacilli (AFB) smear confirms the presence of mycobacteria in the sputum, as AFB staining is generally specific for this group of organisms.
2. Molecular Test (GeneXpert) Negative: The GeneXpert MTB/RIF assay is a rapid nucleic acid amplification test (NAAT) specifically designed to detect DNA from the Mycobacterium tuberculosis complex (MTBC). When a specimen is AFB-positive but GeneXpert-negative, it strongly suggests the presence of Nontuberculous Mycobacteria (NTM). NAATs are able to distinguish M. tuberculosis from nontuberculous mycobacteria.
3. Clinical Picture and Pathogen: The patient's clinical presentation—chronic cough, weight loss, and bilateral upper lobe cavitation—is highly suggestive of pulmonary mycobacterial disease. While this is a classic presentation for active pulmonary tuberculosis (TB), NTM, particularly Mycobacterium avium complex (MAC), are known to cause pulmonary disease that mimics TB, often presenting as apical fibrocavitary disease
164
A 25-year-old patient with drug-susceptible PTB weighing 45kg has been prescribed the
standard regimen 2HRZE/4HR. According to NTP MOP dosing guidelines, which tablet calculation
is CORRECT for the intensive phase using fixed-dose combination (FDC) tablets?
3
38-54kg, 3 tablets
55-70kg, 4 tablets
>70, 5 tablets
165
28-year-old PLHIV patient with CD4 count of 150 cells/mm³ is diagnosed with pulmonary TB.
According to the 2016 Philippine CPG recommendations for TB-HIV co-infection, which
treatment approach is MOST evidence-based?
Start ART started within 8 weeks of TB treatment
TB treatment should be initiated first, followed by ART as soon as possible within the first eight weeks of TB treatment.
◦ An exception exists for patients with profound immunosuppression (e.g., CD4 counts less than 50 cells/mm³), who should receive ART within the first two weeks of initiating TB treatmen
166
A 60-year-old patient with no significant past medical history presents with a 2-month history of a persistent cough, hemoptysis, and night sweats. A chest CT scan reveals a cavitary lesion in the right upper lobe. Which of the following is the most accurate explanation for the formation of
this lesion?
A. The cavitation is a result of an aggressive innate immune response dominated by
neutrophils and mast cells, leading to uncontrolled tissue destruction.
B. The lesion is caused by a Type I hypersensitivity reaction, where IgE antibodies trigger a
massive inflammatory response that liquefies the lung tissue.
C. The cavitation represents a failure of the macrophage-T-cell granuloma to contain the
infection, resulting in caseous necrosis and liquefaction.
D. The lesion is an early, non-specific inflammatory response to the Mycobacterium
tuberculosis infection that typically resolves without intervention.
C
The finding of cavitation in the upper lobes (apical and posterior segments of the right upper lobe are most frequent sites) is characteristic of reactivation TB, which develops remote from the original infection
Option A is incorrect because the organized response meant to restrict the spread is the macrophage-T-cell granuloma, and the cavitation represents the failure of this containment, not simply an aggressive innate response.
Option B is incorrect because TB infection triggers a delayed-type hypersensitivity (T-cell mediated) reaction, not a Type I (IgE antibody mediated) reaction.
Option D is incorrect because cavitation in the upper lobes of an adult with chronic symptoms is typical of reactivation/progressive disease, suggesting a high bacterial burden and extensive disease, which is generally not expected to resolve without intervention
167
According to the Philippine NTP MOP, what is the definition of "Case finding"?
It is the identification of presumptive TB followed by the diagnosis of active TB disease through bacteriological testing or clinical diagnosis.
168
What four cardinal signs and symptoms lasting for two or more weeks are used to identify a presumptive TB case in adults?
Cough, unexplained fever, unexplained weight loss, and night sweats.
169
In the Philippine NTP screening guidelines, if an adult does not have cardinal TB symptoms, what screening test should be offered if one has not been done in the past year?
A chest X-ray screening.
170
What did the 2016 National TB Prevalence Survey in the Philippines reveal about screening for TB using symptoms alone?
It would have missed one-third to two-thirds of bacteriologically confirmed pulmonary TB cases.
171
For which specific populations is chest X-ray screening recommended even if TB symptoms have lasted less than two weeks?
Close contacts of known TB cases and individuals from high-risk populations (e.g., PLHIV, malnourished, immunocompromised).
172
What is the recommended frequency for chest X-ray screening for presumptive TB?
Once a year.
173
In screening for TB in People Living with HIV (PLHIV), when should a chest X-ray be performed?
At the time of HIV diagnosis and annually thereafter.
174
For PLHIV, when should a sputum sample be collected for an Xpert MTB/RIF test?
If they answer "Yes" to any of the four cardinal symptoms (cough, fever, weight loss, night sweats) or if their chest X-ray is suggestive of TB.
175
What are the three main signs and symptoms that would identify a child under 15 years old as a presumptive TB case?
Coughing/wheezing for two weeks or more, unexplained fever for more than one week, and documented weight loss or failure to thrive.
176
For targeted community, workplace, and congregate settings, what is the primary screening tool recommended, and how often should it be done?
Screening all individuals by chest X-ray annually.
177
What is the baseline screening procedure for a newly recruited healthcare worker (HCW)?
TB symptom screening plus a chest X-ray.
178
How often should follow-up screening be conducted for healthcare workers (HCWs)?
TB symptom screening biannually and both symptom screening and chest X-ray annually.
179
For contacts of a Drug-Susceptible TB (DS-TB) case, how often should they be followed up and with what methods?
Every six months for two years, with symptom screening every six months and a chest X-ray screening annually.
180
If a chest X-ray is not feasible for screening contacts of a Drug-Resistant TB (DR-TB) case, what is the recommended alternative procedure?
Proceed directly to an Xpert test for the contact, irrespective of symptoms.
181
According to the NTP MOP, TB preventive treatment (TPT) is currently not recommended for which group of contacts?
Household contacts of DR-TB cases.
182
What is the primary diagnostic test for both PTB and EPTB in adults and children according to the Philippine NTP policies?
A rapid diagnostic test (RDT), such as Xpert MTB/RIF.
183
What is the only contraindication to collecting sputum for the bacteriological diagnosis of TB?
Massive hemoptysis.
184
In an Xpert MTB/RIF test result, what does the notation 'T' signify?
Mycobacterium tuberculosis (MTB) was detected, but rifampicin resistance was not detected.
185
What does an Xpert MTB/RIF result of 'RR' indicate?
MTB was detected, and rifampicin resistance was also detected.
186
If a patient's Xpert MTB/RIF test is negative but their chest X-ray is consistent with pulmonary disease, what may a physician prescribe before deciding to treat for active TB?
A course of broad-spectrum antibiotics that do not have anti-TB activity.
187
In the context of TB diagnosis, what does the term 'Clinically Diagnosed PTB' refer to?
A case where a physician decides to treat for active TB based on clinical judgment (e.g., symptoms and X-ray) even when bacteriological tests like Xpert are negative.
188
If a new TB case with low risk for MDR-TB has an Xpert result of 'MTB detected, rifampicin resistance detected', what is the immediate next step?
Recollect a fresh sputum sample to repeat the Xpert MTB/RIF test and follow the second result for the treatment decision.
189
How is a patient who has been treated for TB for at least one month in the past classified?
As a 'Retreatment' case.
190
In the Philippine NTP guidelines, what is the target treatment success rate for DS-TB patients?
A treatment success rate of greater than or equal to 90%.
191
What is the recommended schedule for follow-up sputum smear microscopy for a new, bacteriologically confirmed pulmonary TB (BCTB) patient?
At the end of the intensive phase (2nd month), at the end of the 5th month, and at the end of treatment (6th month).
192
If a patient's sputum smear is positive at the end of the intensive phase (2nd month), what is the next diagnostic step?
Request an Xpert MTB/RIF test.
193
A patient is declared 'Lost to follow-up' (LTFU) if their treatment has been interrupted for at least _____ consecutive months.
two
194
What is the definition of 'Treatment failed' for a DS-TB patient?
A patient whose sputum smear or culture is positive at five months or later during treatment.
195
In a forest plot, what does the diamond represent?
The summary effect of all included studies, with its apex as the point estimate and its ends as the 95% Confidence Intervals.
196
What measure of diagnostic test accuracy refers to the proportion of persons with a disease who correctly have a positive test?
Sensitivity (sn).
197
In DR-TB treatment, what are the exclusion criteria for the Standard Short All Oral Regimen (SSOR)?
Resistance to any drug in the regimen (except isoniazid), previous exposure to second-line drugs for over a month, pregnancy, or severe EPTB.
198
For DR-TB patients on regimens containing Bedaquiline, Delamanid, Clofazimine, and/or Moxifloxacin, how frequently should an ECG be performed?
Monthly.
199
What does aDSM stand for in the context of DR-TB management?
Active drug safety monitoring and management.
200
A serious adverse event (SAE) is an untoward medical occurrence that results in death, is life-threatening, requires hospitalization, or results in _____.
persistent disability/incapacity
201
According to the Philippine NTP, what is TB Preventive Treatment (TPT)?
Treatment offered to individuals at risk of developing active TB disease to reduce that risk.
202
Which two groups have been the primary targets for isoniazid preventive treatment globally?
People living with HIV (PLHIV) and child household contacts less than 5 years old.
203
True or False: A Tuberculin Skin Test (TST) is required for a child under 5 years old who is a household contact of a bacteriologically confirmed PTB case before starting TPT.
False, TST is not required for this group.
204
What is the recommended TPT regimen that is currently available under the Philippine program?
6H (Isoniazid daily for 6 months).
205
What is the primary mode of transmission for Mycobacterium tuberculosis?
Aerosolized respiratory secretions from an infected person.
206
What is the term for radiographic findings in TB that develop at a time remote from the original infection, typically involving the upper lobes and often showing cavitation?
Reactivation TB.
207
In patients with advanced HIV, what are considered 'atypical' radiographic findings for TB?
Lower lung zone or diffuse opacities and intrathoracic adenopathy, with cavitation being uncommon.
208
What is the diagnostic gold standard for TB, capable of detecting as few as 10 to 1000 viable mycobacteria/mL of sputum?
Mycobacterial culture in liquid media.
209
Which three first-line anti-TB drugs are known to be hepatotoxic?
Isoniazid (INH), Rifampicin (RIF), and Pyrazinamide (PZA).
210
In TB/HIV co-infection, what is a major concern when co-administering rifampicin with antiretroviral therapy (ART)?
Rifampicin is a potent inducer of cytochrome P450 enzymes, which can significantly lower the concentration of many antiretroviral drugs.
211
What is the key principle when modifying a failing TB treatment regimen?
Never add a single new drug; at least two or three new drugs should be added to which the organism is likely susceptible.
212
The recommended treatment for MAC pulmonary disease includes a macrolide, ethambutol, and a _____.
rifamycin (rifampin or rifabutin)
213
What is the term for a positive IGRA result in an M. tuberculosis-uninfected individual due to an increased T-cell response after a recent TST?
IGRA boosting.
214
Why is the Xpert MTB/RIF test not used for monitoring treatment response in DS-TB patients?
Because current-generation PCR-based tests cannot determine MTB viability and may test positive even with nonviable or dead bacilli.
215
What is the recommended management for minor adverse reactions like gastrointestinal intolerance to first-line TB drugs?
Give the drugs at bedtime or with small meals.
216
If a patient on isoniazid experiences a burning sensation in the feet due to peripheral neuropathy, what should be administered?
Pyridoxine (Vitamin B6), typically 50–100 mg daily for treatment.
217
For a patient on a DS-TB regimen who interrupts treatment for more than one month but less than two, and has a negative sputum smear, what is the disposition?
Continue treatment and prolong it to compensate for the missed doses.
218
What is the recommended follow-up schedule for household contacts of DR-TB cases?
Every six months for two years, with symptom screening every six months and a chest X-ray annually.
219
What class of antibiotics, including levofloxacin and moxifloxacin, is a cornerstone of most modern DR-TB regimens?
Fluoroquinolones.
220
What is the definition of a 'New' TB case registration group?
A patient who has never had treatment for TB or who has taken anti-TB drugs for less than one month.
221
For which mycobacterial species is the recommended treatment a three-drug regimen of rifampin, isoniazid, and ethambutol for at least 12 months?
Mycobacterium kansasii.
222
What is the recommended action if a health facility is found to have a compliance rate of 70% or lower with the 2021 TB CPG?
The facility will undergo re-orientation by one of the main professional societies (PhilCAT, PSMID, PCCP).
223
A major breakthrough in NAAT has been the development of _____, an automated, real-time PCR assay that detects M. tuberculosis complex and rifampin resistance.
Xpert MTB/RIF
224
What percentage of the world's population is estimated to have latent tuberculosis infection (LTBI)?
Approximately 22% of the world's population, or 1.7 billion people, are estimated to have LTBI.
225
If left untreated, what percentage of individuals with latent tuberculosis infection (LTBI) will develop active disease?
Approximately 5–10% of latently infected individuals will develop active TB disease if untreated.
226
What is the basis for diagnosing latent tuberculosis (LTBI), given there are no direct definitive tests?
LTBI remains a clinical diagnosis based on evidence of prior TB infection and the exclusion of active disease.
227
What are the only two approaches currently available to identify individuals with asymptomatic TB infection?
The two available approaches are the tuberculosis skin test (TST) and interferon-gamma ($IFN-\gamma$) release assays (IGRAs).
228
What is the primary goal of screening for latent tuberculosis infection (LTBI)?
The goal is to identify Mycobacterium tuberculosis (Mtb)-infected individuals who are at an increased risk of developing active TB and would benefit from treatment.
229
Screening for LTBI should target individuals in which two high-risk groups?
The two high-risk groups are (1) individuals with increased risk of Mtb infection and (2) individuals with clinical conditions associated with a high risk of reactivation.
230
Why is untargeted screening for LTBI in low-incidence settings not recommended?
It is not cost-effective and would yield more false-positive results than true-positive results, leading to overtreatment.
231
If an initial TST or IGRA test is negative for a close contact, when should testing be repeated after the last exposure?
Testing should be repeated 8 to 10 weeks after the last exposure to account for the time needed for delayed hypersensitivity to develop.
232
Why might an IGRA be preferred over a TST for screening individuals with a history of BCG vaccination?
IGRA is a more specific screening test because its antigens are absent from BCG strains, reducing the likelihood of false-positive results.
233
What is the strongest known risk factor for the progression of LTBI to active disease?
Human immunodeficiency virus (HIV) infection is the strongest known risk factor for progression to active disease.
234
For an HIV-infected individual with a negative LTBI test and a CD4 count below 200 cells/µL, when should repeat testing be performed?
Repeat testing should be done after initiating antiretroviral therapy when the CD4 count increases to 200 cells/µL or greater.
235
What daily dose of corticosteroids for one month or longer is considered a high risk for reactivation of TB?
A corticosteroid dose of >15mg daily for >1 month is considered a high risk for reactivation.
## Footnote
For individuals with HIV, any daily dose equivalent to ≥15 mg of prednisone is cited as a cause of diminished immune response, which can lead to false-negative TST or IGRA results
236
Within how many hours after placement must a Tuberculin Skin Test (TST) be read?
The TST must be read between 48 and 72 hours after placement.
237
The lowest TST cut-off for a positive result ($\ge5$ mm) is used for individuals with the highest TB risk to minimize the proportion of _____.
false negatives
238
What is the TST cut-point for a positive result in individuals with no known TB risk factors?
The cut-point is an induration of >15 mm.
239
What specific Mtb antigens, which are absent from all BCG strains, do IGRAs measure the T-cell response to?
IGRAs measure the response to early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10).
240
For which age group is the TST preferred over an IGRA for LTBI screening?
TST is preferred over IGRA for children younger than 5 years.
241
Why might IGRA results be uninterpretable more frequently in children under 5 years old?
Young children may have a lower IFN-\gamma$ response to Mtb antigens and mitogen, possibly due to immunologic immaturity.
242
For which two groups of people is an IGRA preferred over a TST for LTBI screening?
IGRA is preferred for individuals who have received the BCG vaccine and for groups with low rates of returning to have TSTs read (e.g., homeless individuals).
243
Under what circumstance might dual TST and IGRA testing be considered for a person with a negative initial test?
It may be considered when the risks for Mtb infection, disease progression, and poor outcomes are all high, and clinical suspicion persists.
244
How should a positive TST result be interpreted in an individual who has previously received a BCG vaccination, according to U.S. guidelines?
BCG-vaccinated individuals with positive TST reactions should be regarded as true positives, without modifying the positivity criteria.
245
Besides prior BCG vaccination, what is another common cause of false-positive TST reactions, particularly in the southern United States?
Infection with nontuberculous mycobacteria (NTM) is another cause of false-positive TST reactions.
246
Which four species of nontuberculous mycobacteria can reduce IGRA specificity because they express ESAT-6 and/or CFP-10?
Mycobacterium kansasii, M. szulgai, M. marinum, and M. flavescens can reduce IGRA specificity.
247
If repeat testing for Mtb infection is required for an individual with a known tuberculin allergy, which test should be performed?
An IGRA should be performed, as a repeat TST is contraindicated due to the allergy.
248
What is the phenomenon called when a remote Mtb infection with a waned immune response leads to a positive TST only upon repeat testing?
This phenomenon is referred to as "boosting".
249
To establish a baseline LTBI status and avoid misinterpreting a boosted reaction as a new infection, what procedure is recommended for individuals requiring serial screening?
A two-step TST is recommended to establish a baseline
The two-step TST protocol follows these specific steps:
1. First Test: A standard TST is administered and read.
2. Wait Period: If the first test is negative, the clinician waits 1 to 3 weeks.
3. Second Test: A second TST is performed.
4. Interpretation: If the second test is positive, it is attributed to boosting from a past infection, and the individual is classified as having Latent TB Infection (LTBI) (after active disease is ruled out).
.
250
To minimize the risk of a false-positive IGRA result from boosting, blood for IGRA testing should be collected within what time frame relative to a TST placement?
Blood should be collected either within 3 days of TST placement or more than 3 months after TST placement.
251
What is the cause of false-negative TST or IGRA results in immunosuppressed individuals?
False-negative results are caused by decreased immunocompetence or, specifically for TST, skin test anergy.
252
What should be done if an individual has an uninterpretable IGRA result on repeat testing?
The individual should undergo a TST, and the TST result should be used to inform subsequent management.
253
In the standard 9-month treatment regimen for LTBI, what is the maximum daily dose of Isoniazid (INH) for an adult?
The maximum daily dose of INH is 300 mg.
254
In the United States and other low-burden countries, what is the source of 80% or more of all active TB cases?
80% or more of TB cases result from the reactivation of a latent infection.
255
What is the TST cut-point for positivity in recent immigrants (<5 years) from TB-endemic countries?
The cut-point is an induration of $\ge10$ mm.
256
For organ-transplant recipients, what is the minimum size of induration for a TST to be considered positive?
An induration of >5 mm is considered a positive TST for organ-transplant recipients.
257
Which key virulence factor of *M. tuberculosis* is secreted by the ESX-1 type VII secretion system and is a target for host immune responses?
The ESX-1 system secretes the proteins ESAT-6 and CFP-10, which are important for virulence and immune recognition.
258
The characteristic feature of tuberculous granulomas is _____ necrosis, where the tissue texture resembles soft cheese.
caseating
259
How does *M. tuberculosis* primarily survive and replicate within macrophages?
It survives by perturbing the maturation of the phagosome, preventing it from fusing with the lysosome.
260
What is the central role of the ESX-1 type VII secretion system in the pathogenesis of *M. tuberculosis*?
The ESX-1 system is essential for perforating the phagosome membrane, allowing the bacteria to access the host cell cytosol.
261
Which cytokine plays an essential role in activating the microbicidal activities of macrophages to control tuberculosis?
$IFN-\gamma$ (Interferon-gamma) plays an essential role in activating macrophages.
262
What is the primary role of Interleukin (IL)-12 in the immune response to tuberculosis?
IL-12 directs the differentiation of CD4 T cells into type 1 T helper cells that secrete $IFN-\gamma$.
263
The inflammasome is a cytosolic immune sensor that, when activated by *M. tuberculosis*, leads to the secretion of which two important cytokines?
The inflammasome leads to the secretion of nterleukin-1β (IL-1β) and Interleukin-18 (IL-18)
264
What is the most commonly reported symptom of pulmonary tuberculosis?
A persistent cough, which is generally productive of mucus and sometimes blood, is the most common symptom.
265
Besides a persistent cough, what systemic symptoms often accompany active pulmonary TB?
Systemic symptoms include fever, night sweats, and weight loss.
266
What is the WHO-recommended initial diagnostic test for *M. tuberculosis* where available, due to its speed and sensitivity?
Rapid molecular tests, such as Xpert MTB/RIF, are recommended as the initial diagnostic test.
267
What is the term for enhancing sputum production by having a patient inhale a hypertonic saline mist?
This procedure is known as sputum induction.
268
The sensitivity of sputum smear microscopy is relatively low, requiring approximately how many bacilli per milliliter of secretions for detection?
Detection requires approximately 10,000 bacilli/mL of secretions.
269
What is considered the current diagnostic gold standard for tuberculosis, capable of detecting as few as 10 to 100 viable mycobacteria/mL?
Culture in liquid media is considered the current diagnostic gold standard.
270
The Xpert MTB/RIF assay is a real-time PCR test that detects *M. tuberculosis* complex and mutations associated with resistance to which drug?
The assay detects mutations associated with resistance to rifampin.
271
Which urine-based test for TB diagnosis is most useful in individuals with advanced HIV-associated immunosuppression (low CD4 counts)?
The lipoarabinomannan (LAM) antigen test is most useful in this population.
initial diagnostic test for all HIV-infected individuals who present with ***TB symptoms***, regardless of their CD4 cell count. This applies to both:
* Inpatients (hospitalized).
* Outpatients.
***Asymptomatic ***HIV-Infected Patients (Based on CD4 Count) provided they meet specific levels of immunosuppression:
* Inpatients: If the CD4 cell count is less than 200 cells/μL.
* Outpatients: If the CD4 cell count is less than 100 cells/μL.
Recommended for HIV-infected patients who are ***seriously ill, ***as the sensitivity of the test increases significantly as the CD4 count decreases. This is because advanced HIV leads to a higher mycobacterial burden, an increased likelihood of extrapulmonary spread (genitourinary TB), and increased glomerular permeability, all of which allow more LAM antigen to enter the urine
272
For all initial *M. tuberculosis* isolates, what type of testing is recommended due to concerns about resistant organisms?
Drug susceptibility testing is recommended for all initial isolates.
273
In pleural TB, what T-lymphocyte enzyme, when found at elevated levels (>35 U/L) in pleural fluid, has high sensitivity and specificity for diagnosis?
Adenosine deaminase (ADA) has high sensitivity and specificity for diagnosing pleural TB.
274
What is the most common form of extrapulmonary TB, usually presenting as painless swelling of cervical or supraclavicular lymph nodes?
Tuberculous lymphadenitis (scrofula) is the most common form of extrapulmonary TB.
275
In suspected genitourinary TB, what urinalysis finding should prompt an evaluation for TB?
The finding of pyuria (white blood cells in urine) in an acidic urine with no organisms isolated from a routine culture.
276
In spinal TB, also known as Pott disease, the infection typically involves two adjacent vertebrae and the _____.
intervertebral disc
277
What is the most lethal form of TB, which is fatal if left untreated?
TB meningitis is the most lethal form of tuberculosis.
## Footnote
TB Meningitis (Adults >14 years): Dexamethasone 0.4 mg/kg/24 hr with a reducing course over six to eight weeks
278
What is the core principle regarding the addition of new drugs to a failing TB treatment regimen?
A single new drug should never be added to a failing regimen; instead, two or three new, likely effective drugs must be added.
279
Drug-induced hepatitis is the most frequent serious adverse reaction to first-line TB drugs. Which three drugs can all cause liver injury?
Isoniazid (INH), rifampin (RIF), and pyrazinamide (PZA) can all cause liver injury.
280
For patients with cavitation on their initial chest radiograph and a positive culture at 2 months, the continuation phase of treatment is typically extended to a total of how many months?
The total duration of therapy is extended to 9 months.
281
The preferred term for mycobacteria other than *M. tuberculosis* or *M. leprae* is _____.
nontuberculous mycobacteria (NTM)
282
Unlike *M. tuberculosis*, NTM do not appear to be transmitted from _____ in the absence of extraordinary circumstances.
human to human
283
What is the most common NTM species causing pulmonary disease in North America?
The *Mycobacterium avium* complex (MAC) is the most common cause of NTM pulmonary disease.
284
What are the two distinct clinical and radiographic presentations of MAC pulmonary disease?
The two presentations are apical fibrocavitary disease (similar to TB) and nodular bronchiectatic disease.
285
What is the cornerstone of any treatment regimen for MAC pulmonary disease?
A macrolide (azithromycin or clarithromycin) is the cornerstone of MAC therapy.
286
What is the recommended treatment regimen for nodular/bronchiectatic MAC disease?
A three-drug regimen of a macrolide (azithromycin or clarithromycin), ethambutol, and a rifamycin (rifampin or rifabutin).
287
For treatment-refractory MAC pulmonary disease, what inhalational therapy should be added to the guideline-based oral regimen?
Amikacin liposome inhalation suspension (ALIS) should be added.
288
Which NTM species that causes lung disease most closely parallels the clinical course and radiographic abnormalities of *M. tuberculosis*?
*Mycobacterium kansasii* lung disease most closely resembles tuberculosis.
289
Which subspecies of *M. abscessus* is more responsive to macrolide-based therapy due to a nonfunctional *erm(41)* gene?
*M. abscessus* subsp. *massiliense* is more responsive to treatment.
290
Which NTM species has been linked to a global outbreak of disseminated disease related to contaminated heater-cooler units used during cardiac surgery?
*Mycobacterium chimaera* has been linked to this outbreak.
Murray
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