Pneumonia

Question 1

Most common mode of entry of microbial pathogens into the alveolar level

Answer 1

Aspiration from oropharynx

Question 2

Stages/evolution of pneumonia and what are seen during those stages

Answer 2

1. Edema/congestion: Proteinaceous exudates, a lot of bacteria
2. Red hepatization: Erythrocytes, occasional bacteria
3. Gray hepatization: Neutrophils, fibrin deposits, no more erythrocytes and bacteria
4. Resolution: Macrophages, clearing of debris

Question 3

Patterns of CAP, HAP, VAP

Answer 3

CAP: Bronchopneumonia
HAP: Lobar pneumonia
VAP: Respiratory bronchiolitis

Question 4

A serious consequence of pneumonia caused by S. aureus

Answer 4

Necrotizing pneumonia

Question 5

Possible CAP pathogen if with exposure to sheep, goats and parturient cats

Answer 5

Coxiella burnetti

Question 6

Possible CAP pathogen if with exposure to rabbits

Answer 6

Francisella tularensis

Question 7

Possible CAP pathogen if with exposure to birds

Answer 7

Chlamydophila psittaci, Histoplasma capsulatum

Question 8

Possible CAP pathogen if with exposure to bats

Answer 8

Histoplasma capsulatum

Question 9

Possible CAP pathogen if stayed in a hotel or on cruise ship in previous 2 weeks

Answer 9

Legionella spp.

Question 10

Possible CAP pathogen if with structural lung disease

Answer 10

Pseudomonas aeruginosa, Burkholderia cepacia, Staphylococcus aureus

Question 11

Possible CAP pathogen if with decreased level of consciousness, dementia, stroke

Answer 11

Anaerobes, gram negative enteric bacteria

Question 12

Possible CAP pathogen if with lung abscess

Answer 12

MRSA, anaerobes, fungi, atypical mycobacteria, Mycbacterium tuberculosis

Question 13

Possible CAP pathogen if travelled to Ohio or St. Lawrence river valleys

Answer 13

Histoplasma capsulatum

Question 14

Possible CAP pathogen if travelled to Southwestern US

Answer 14

Hantavirus, Coccidioides spp.

Question 15

Possible CAP pathogen if travelled to Southeast Asia

Answer 15

Burkholderia pseudomallei, avian influenza virus

Question 16

Possible CAP pathogen if with pneumatoceles

Answer 16

Staphylococcus aureus

Question 17

What is an adequate sputum specimen for culture

Answer 17

PMN >25, squamous epithelial cells < 10 per lpf

Question 18

Most frequently isolated pathogen in blood cultures of patients with CAP

Answer 18

Streptococcus pneumoniae

Question 19

Indications for doing blood culture in CAP

Answer 19

Neutropenia, asplenia, complement deficiencies, chronic liver disease, severe CAP

Question 20

Standard of diagnosis for respiratory viral infection

Answer 20

PCR of nasopharyngeal swabs

Question 21

Components of CURB-65 and significance of score

Answer 21

Confusion, urea nitrogen >7mmol/l, RR >/= 30, BP = 90/60, age >/= 65

Score = 0: can be treated as outpatient
Score = 2: must be admitted
Score = 3: must be admitted at the ICU

Question 22

Most important risk factor for antibiotic-resistant pneumococcal infection

Answer 22

Use of antibiotic within the previous 3 months

Question 23

Sensitivity classification of pneumococcal strains

Answer 23

Susceptible: MIC = 2
Intermediate: MIC > 2-4
Resistant: MIC > 8

Question 24

Definition of MDR strains

Answer 24

Resistant to >/= 3 drugs of antimicrobials with different MOA

Question 25

Mechanism of resistance of MRSA

Answer 25

mecA gene - encodes for resistance to all beta lactam drugs Type II or III for HA-MRSA Type IV for CA-MRSA

Question 26

Enterobacter spp. are inherently resistant to what and how to treat it

Answer 26

Resistant to cephaolsporins | Treat with fluoroquinolones or carbapenems

Question 27

Diagnosis, potential pathogens, and treatment for CAP-LR

Answer 27

Diagnosis: 1. Stable VS: RR<30, HR<125, BP>90/60, temp >36 or <40 2. No altered mental state of acute onset 3. No suspected aspiration 4. No or stable comorbid 5. CXR findings: localized infiltrates, no pleural effusion Potential pathogens: S. pneumoniae, H. influenzae, M. pneumoniae, M. catarrhalis, C. pneumoniae, enteric gram negative bacilli (among those with comorbids) Treatment: 1. No comorbids: PO Amoxicillin 1g TID or PO extended macrolide 2. Stable comorbids: (PO BLIC or PO 2nd gen cephalosporin) +/- PO extended macrolide

Question 28

Diagnosis, potential pathogens, and treatment for CAP-MR

Answer 28

Diagnosis: 1. Unstable VS: RR>/=30, HR>/=125, BP=90/60, temp =36 or >/=40 2. With altered mental state of acute onset 3. With suspected aspiration 4. Unstable/decompensated comorbids: uncontrolled DM, active malignancies, neurologic disease in evolution, CHF class II-IV, unstable CAD, ESRD on HD, uncompensated COPD, decompensated liver disease 5. CXR findings: multilobar infiltrates, with pleural effusion Potential pathogens: S. pneumoniae, H. influenzae, M. pneumoniae, M. catarrhalis, C. pneumoniae, enteric gram negative bacilli, Legionella, anaerobes Treatment: 1. (IV non-antipseudomonal BLIC/2nd-3rd gen cephalosporin) + (PO extended macrolide or PO respiratory fluoroquinolone) 2. Suspected aspiration pneumonia: + IV clindamycin if did not use ampicillin sulbactam for BLIC or moxifloxacin for fluoroquinolone

Question 29

Diagnosis, potential pathogens, and treatment for CAP-HR

Answer 29

Diagnosis: CAP-MR + any of the ff 1. Severe sepsis 2. Septic shock 3. Need for mechanical ventilation Potential pathogens: S. pneumoniae, H. influenzae, M. pneumoniae, M. catarrhalis, C. pneumoniae, enteric gram negative bacilli, Legionella, anaerobes, S. aureus, P. aeruginosa Treatment: 1. No risk for P. aeruginosa: IV non-antipseudomonal BLIC + (IV extended macrolide or IV respiratory fluoroquinolone) 2. With risk for P. aeruginosa: [(IV antipseudomonal BLIC/cephalosporin/carbapenem) + IV extended macrolide + IV aminoglycoside] OR [(IV antipseudomonal BLIC/cephalosporin/carbapenem) + (IV ciprofloxacin or high dose IV levofloxacin)] 3. With risk for MRSA: + (IV vancomycin or IV linezolid or IV clindamycin)

Question 30

Indication to repeat CXR after initiating treatment

Answer 30

No improvement after 72 hours

Question 31

Duration of treatment

Answer 31

1. Most bacterial pneumonia except those in #2: 5-7 days; 3-5 days if azalides for S. pneumoniae 2. Enteric gram neg, S. aureus, P. aeruginosa a. MSSA: 7-14 days if nonbacteremic, 21 days if bacteremic b. MRSA: 7-21 days if nonbacteremic, 28 days if bacteremic c. P. aeruginosa: 14-21 days if nonbacteremic, 28 days if bacteremic 3. Mycoplasma, Chlamydophila: 10-14 days 4. Legionella: 14-21 days; 10 days if azalides

Question 32

Criteria for hospital discharge

Answer 32

1. Temp 36-37.5 2. HR < 100 3. RR 16-24 4. SBP >90 5. sO2 >90 6. Functioning GI tract - on PO meds

Question 33

Repeat CXR post discharge

Answer 33

4-6 weeks after discharge to establish new baseline and rule out malignancy (not prior to discharge if clinically improving)

Question 34

Main risk factors for P. aeruginosa infection

Answer 34

1. Structural lung disease 2. Recent antibiotic use 3. Glucocorticoids

Question 35

Diagnostic threshold for quantitative ET aspirate of more proximal samples

Answer 35

10^6 cfu/ml

Question 36

Diagnostic threshold for protected specimen brush method of more distal samples

Answer 36

10^3 cfu/ml

Question 37

Major risk factor for infection with MRSA and ESBL-positive strains

Answer 37

Use of beta lactam drugs (cephalosporins)

Question 38

Empiric treatment for HCAP

Answer 38

1. Without risk factors for MDR pathogens: SINGLE AGENT - ceftriaxone or IV fluoroquinolones or IV ampicillin/sulbactam or ertapenem 2. With risk factors for MDR pathogens: 3 AGENTS - IV antipseudomonal BLIC/cephalosporin/carbapenem + (IV aminoglycoside or IV fluoroquinolone) + (IV linezolid or IV vancomycin)

Question 39

Major difference of CAP and VAP

Answer 39

Lower incidence of atypical pathogens in VAP (exception is Legionella)

Question 40

Most sensitive component of CPIS

Answer 40

Improvement in oxygenation

Question 41

Major difference of HAP and VAP

Answer 41

Higher frequency of non-MDR pathogens and anaerobes in HAP