In TB, the most infectious patients have
cavitary pulmonary disease
In absolute terms, the most potent risk factor for TB among infected individuals is
HIV coinfection
in the very early phases of infection, the predominant cells infected by M. tuberculosis are
Myeloid dendritic cells
inhibits the intracellular increase of Ca2+. Thus, the Ca2+/calmodulin pathway (leading to phagosome–lysosome fusion) is impaired, and the bacilli survive within the phagosomes by blocking fusion
Lipoarabinomannan
encodes for a catalase/peroxidase enzyme that protects against oxidative stress and is required for isoniazid activation and subsequent bactericidal activity
katG gene
The lesion forming after initial infection ___ is usually peripheral and accompanied by transient hilar or paratracheal lymphadenopathy
(Ghon focus)
The Ghon focus, with or without overlying pleural reaction, thickening, and regional lymphadenopathy, is referred to as
Ghon complex
rupture of a dilated vessel in a cavity
(Rasmussen’s aneurysm
In descending order of frequency, the extrapulmonary sites most commonly involved in TB are
LPG BJMP
the lymph nodes, pleura, genitourinary tract, bones and joints, meninges, peritoneum, and pericardium
The most common presentation of extrapulmonary TB in both HIV-seronegative individuals and HIV-infected patients
Lymph Node TB (Tuberculous Lymphadenitis)
as painless swelling of the lymph nodes, most commonly at posterior cervical and supraclavicular sites
documentation of culture-negative pyuria in acidic urine should raise the suspicion of
TB
Most commonly affected in Skeletal TB
Weight-bearing joints (the spine in 40% of cases, the hips in 13%, and the knees in 10%
Spinal TB (Pott’s disease or tuberculous spondylitis; most common site of spinal TB in adults
the lower thoracic and upper lumbar vertebrae are usually affected in adults
WHO now recommends that adjuvant glucocorticoid therapy with either dexamethasone or prednisolone, tapered over 6–8 weeks, should be used in CNS TB.
Dexa dosage
The dexamethasone schedule was (1) 0.4 mg/kg per day given IV with tapering by 0.1 mg/kg per week until the fourth week, when 0.1 mg/kg per day was administered; followed by (2) 4 mg/d given by mouth with tapering by 1 mg per week until the fourth week, when 1 mg/d was administered
Most commonly involved sites in GI TB
Terminal ileum and cecum
Pathognomonic of miliary TB
Choroidal tubercles
It consists of exacerbations in systemic manifestations (lymphadenopathy, fever) or respiratory signs (worsening of pulmonary infiltrations, pleural effusion) as well as laboratory or radiographic manifestations of TB
immune reconstitution inflammatory syndrome (IRIS) or TB immune reconstitution disease
When should ART be initiated in CNS Tb
After 8 weeks
ART should not be initiated during the first 8 weeks of TB treatment in patients with TB meningitis
Glucocorticoids in severe paradoxical reactions IRIS
prednisolone given for 4 weeks at a low dosage (1.5 mg/kg per day for 2 weeks and half that dose for the remaining 2 weeks
Test preferred in with low TB and HIV burdens,
IGRAs have previously been reported to be more specific than the TST
TST <5y.o
IGRA over 5y.o
When to stop TB drugs
A. Pyrazinamide
B. Rifampin
C. Ethambutol
A. Gouty arthritis
B. Autoimmune thrombocytopenia
C. Optic neuritis
Sensitivity varies according to specimen type being the lowest in a. __________ and the highest in b. _________ and c. _________
Highest in pleural fluid (50% with Xpert MTB/RIF and 71% with Ultra) and the highest in synovial fluid (97%) and lymph node biopsy (100% with Ultra
Hat is the greatest limitation of PPD?
lack of mycobacterial species specificity
What is the dose to prevent isoniazid-related neuropathy?
pyridoxine (10–25 mg/d) should be added to the regimen given to persons at high risk of vitamin B6 deficiency
