Pneumonia Flashcards
Most common mode of entry of microbial pathogens into the alveolar level
Aspiration from oropharynx
Stages/evolution of pneumonia and what are seen during those stages
- Edema/congestion: Proteinaceous exudates, a lot of bacteria
- Red hepatization: Erythrocytes, occasional bacteria
- Gray hepatization: Neutrophils, fibrin deposits, no more erythrocytes and bacteria
- Resolution: Macrophages, clearing of debris
Patterns of CAP, HAP, VAP
CAP: Bronchopneumonia
HAP: Lobar pneumonia
VAP: Respiratory bronchiolitis
A serious consequence of pneumonia caused by S. aureus
Necrotizing pneumonia
Possible CAP pathogen if with exposure to sheep, goats and parturient cats
Coxiella burnetti
Possible CAP pathogen if with exposure to rabbits
Francisella tularensis
Possible CAP pathogen if with exposure to birds
Chlamydophila psittaci, Histoplasma capsulatum
Possible CAP pathogen if with exposure to bats
Histoplasma capsulatum
Possible CAP pathogen if stayed in a hotel or on cruise ship in previous 2 weeks
Legionella spp.
Possible CAP pathogen if with structural lung disease
Pseudomonas aeruginosa, Burkholderia cepacia, Staphylococcus aureus
Possible CAP pathogen if with decreased level of consciousness, dementia, stroke
Anaerobes, gram negative enteric bacteria
Possible CAP pathogen if with lung abscess
MRSA, anaerobes, fungi, atypical mycobacteria, Mycbacterium tuberculosis
Possible CAP pathogen if travelled to Ohio or St. Lawrence river valleys
Histoplasma capsulatum
Possible CAP pathogen if travelled to Southwestern US
Hantavirus, Coccidioides spp.
Possible CAP pathogen if travelled to Southeast Asia
Burkholderia pseudomallei, avian influenza virus
Possible CAP pathogen if with pneumatoceles
Staphylococcus aureus
What is an adequate sputum specimen for culture
PMN >25, squamous epithelial cells < 10 per lpf
Most frequently isolated pathogen in blood cultures of patients with CAP
Streptococcus pneumoniae
Indications for doing blood culture in CAP
Neutropenia, asplenia, complement deficiencies, chronic liver disease, severe CAP
Standard of diagnosis for respiratory viral infection
PCR of nasopharyngeal swabs
Components of CURB-65 and significance of score
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
Most important risk factor for antibiotic-resistant pneumococcal infection
Use of antibiotic within the previous 3 months
Sensitivity classification of pneumococcal strains
Susceptible: MIC = 2
Intermediate: MIC > 2-4
Resistant: MIC > 8
Definition of MDR strains
Resistant to >/= 3 drugs of antimicrobials with different MOA
Mechanism of resistance of MRSA
mecA gene - encodes for resistance to all beta lactam drugs
Type II or III for HA-MRSA
Type IV for CA-MRSA
Enterobacter spp. are inherently resistant to what and how to treat it
Resistant to cephaolsporins
Treat with fluoroquinolones or carbapenems
Diagnosis, potential pathogens, and treatment for CAP-LR
Diagnosis:
- Stable VS: RR<30, HR<125, BP>90/60, temp >36 or <40
- No altered mental state of acute onset
- No suspected aspiration
- No or stable comorbid
- 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:
- No comorbids: PO Amoxicillin 1g TID or PO extended macrolide
- Stable comorbids: (PO BLIC or PO 2nd gen cephalosporin) +/- PO extended macrolide
Diagnosis, potential pathogens, and treatment for CAP-MR
Diagnosis:
- Unstable VS: RR>/=30, HR>/=125, BP=90/60, temp =36 or >/=40
- With altered mental state of acute onset
- With suspected aspiration
- 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
- 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:
- (IV non-antipseudomonal BLIC/2nd-3rd gen cephalosporin) + (PO extended macrolide or PO respiratory fluoroquinolone)
- Suspected aspiration pneumonia: + IV clindamycin if did not use ampicillin sulbactam for BLIC or moxifloxacin for fluoroquinolone
Diagnosis, potential pathogens, and treatment for CAP-HR
Diagnosis: CAP-MR + any of the ff
- Severe sepsis
- Septic shock
- 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:
- No risk for P. aeruginosa: IV non-antipseudomonal BLIC + (IV extended macrolide or IV respiratory fluoroquinolone)
- 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)]
- With risk for MRSA: + (IV vancomycin or IV linezolid or IV clindamycin)
Indication to repeat CXR after initiating treatment
No improvement after 72 hours
Duration of treatment
- Most bacterial pneumonia except those in #2: 5-7 days; 3-5 days if azalides for S. pneumoniae
- 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 - Mycoplasma, Chlamydophila: 10-14 days
- Legionella: 14-21 days; 10 days if azalides
Criteria for hospital discharge
- Temp 36-37.5
- HR < 100
- RR 16-24
- SBP >90
- sO2 >90
- Functioning GI tract - on PO meds
Repeat CXR post discharge
4-6 weeks after discharge to establish new baseline and rule out malignancy (not prior to discharge if clinically improving)
Main risk factors for P. aeruginosa infection
- Structural lung disease
- Recent antibiotic use
- Glucocorticoids
Diagnostic threshold for quantitative ET aspirate of more proximal samples
10^6 cfu/ml
Diagnostic threshold for protected specimen brush method of more distal samples
10^3 cfu/ml
Major risk factor for infection with MRSA and ESBL-positive strains
Use of beta lactam drugs (cephalosporins)
Empiric treatment for HCAP
- Without risk factors for MDR pathogens: SINGLE AGENT - ceftriaxone or IV fluoroquinolones or IV ampicillin/sulbactam or ertapenem
- With risk factors for MDR pathogens: 3 AGENTS - IV antipseudomonal BLIC/cephalosporin/carbapenem + (IV aminoglycoside or IV fluoroquinolone) + (IV linezolid or IV vancomycin)
Major difference of CAP and VAP
Lower incidence of atypical pathogens in VAP (exception is Legionella)
Most sensitive component of CPIS
Improvement in oxygenation
Major difference of HAP and VAP
Higher frequency of non-MDR pathogens and anaerobes in HAP