Pneumonia Flashcards
Pathogenesis of Pneumonia
Most commonly: Bacteria infection Mechanism: - Aspiration of oropharyngeal secretions - Inhalation of aerosols - Hematogenous spreading
Clinical presentation & diagnosis of Pneumonia
Signs & symptoms:
- Cough, chest pain, SOB, hypoxia, Fever > 38C, chills
- Tachypnea, tachycardia, hypotension
- Leukocytosis
- Fatigue, anorexia, nausea, changes in mental status
Physical examination
- Diminished breaths & inspiratory crackles
Radiographic findings
- New infiltrates/ dense consolidations
Laboratory findings
- Non-specific so NOT RECOMMENDED as guide for antibiotic initiation/discontinuation
Respiratory cultures
- Sputum: Low yield; frequent contamination (NOT RECC)
- LRT samples: Less contamination but invasive sampling
Blood cultures
- To rule out bacteremia
Urinary antigen tests
- NOT RECC as indicates exposure to respective pathogen, but not necessarily infection
Classifications of pneumonia
1) Community-acquired (CAP): < 48h after hospital admission
2) Hospital-acquired (HAP): >= 48h after hospital admission
3) Ventilator-associated (VAP): > 48h after mechanical ventilation
Risk factors for CAP
- Age >= 65yo
- Previous hospitalisation for CAP
- Smoking
- COPD, DM, HF, cancer, immunosupression
Prevention of CAP
- Smoking cessation
- Immunization (Influenza, pneumococcal)
Microbiology of OUTPATIENT bacterial CAP
- Streptococcus penumoniae
- Haemophilus influenzae
- Atypical (Mycoplasma, Chlamydophilia)
Microbiology of INPATIENT (NON-SEVERE) bacterial CAP
- Streptococcus penumoniae
- Haemophilus influenzae
- Atypical (Mycoplasma, Chlamydophilia, Legionella)
Microbiology of INPATIENT (SEVERE) bacterial CAP
- Streptococcus penumoniae
- Haemophilus influenzae
- Atypical (Mycoplasma, Chlamydophilia, Legionella)
PLUS
- Staph. aureus
- Gram (-) (Klebsiella, Burkholderia Pseudomallei)
Burkholderia Pseudomallei: Can cause Meliodosis
Risk stratification for Pneumonia
1) IDSA/ ATS Criteria for Severe CAP
- >= 1 major criteria/ >= 3 minor criteria
Major: Mechanical ventilation
Septic shock requiring vasoactive meds
Minor: RR >= 30 breaths/min
PaO2/FiO2 <= 250 (Hypoxia marker)
Multilobar infiltrates
Confusion/disorientation
Uremia (Urea > 7mmol/L)
Leukopenia (WBC < 4 x 10^9)
Hypothermia ( < 36C )
Hypot/s requiring aggressive fluid resuscitation
2) Pneumonia Severity Index (PSI)
3) CURB-65
Empiric treatment model for CAP
ALL CAP Patiients:
1) Standard regimen - Min coverage based on location (inpatient/outpatient) & risk stratification
For inpatients only:
2) Anaerobic coverage
3) MRSA coverage
4) Pseudomonal coverage
Antibiotic regimen for OUTPATIENT CAP
If generally healthy:
1) B-lactam (Amoxicillin) OR
2) Respiratory FQ (Levofloxacin/Moxifloxacin)
If chronic heart/lung/liver/renal disease/DM/Alcoholism/Malignancy/Asplenia:
1) B-lactam (Augmentin/Cefuroxime)
+ Macrolide (Clarithromycin/Azythromycin) OR
Doxycycline
2) Respiratory FQ (Levofloxacin/Moxifloxacin)
Route: PO
Antibiotic regimen for INPATIENT CAP (Non-Severe)
1) IV B-lactam (Augmentin/Ceftriaxone)
+ PO Macrolide (Clarithromycin/Azythromycin) OR
PO Doxycycline
2) IV Respiratory FQ (Levofloxacin/Moxifloxacin)
Antibiotic regimen for INPATIENT CAP (Severe)
1) IV B-lactam (Augmentin) + Ceftazidime
+ PO Macrolide (Clarithromycin/Azythromycin) OR
PO Doxycycline
2) IV Respiratory FQ (Levofloxacin/Moxifloxacin)
+ Ceftazidime
Indication for ANAEROBIC COVERAGE for Inpatient CAP
- Lung abscess
- Empyema (collection of pus in alveoli space)
Common anaerobes for Inpatient CAP
- Bacteriodes fragilis
- Prevotella spp.
- Porphyromas spp.
- Fusobacterium spp.
Antibiotic to add for ANAEROBIC COVERAGE
IV/PO Clindamycin OR IV/PO Metronidazole
Note: Augmentin & Moxifloxacin have anaerobic coverage
Indication for MRSA COVERAGE for Inpatient CAP
- Prior respiratory isolation of MRSA in last 1 year
- Severe CAP only: Hospitalization & received IV antibiotics within last 90 days
Antibiotic to add for MRSA COVERAGE
IV Vancomycin or IV/PO Linezolid
Indication for PSEUDOMONAL COVERAGE for Inpatient CAP
- Prior respiratory isolation of Pseudomonas aeruginosa in last 1 year
Antibiotic to add for PSEUDOMONAL COVERAGE
Options:
- IV Piperacillin/Tazobactam
- IV Cefepime
- IV Meropenem (Not preferred)
- IV/PO Levofloxacin (Severe)
BUT usually will already give IV Ceftazidime
- Only case to consider to modify standard regimen to include Pseodomonal coverage is in INPATIENT, NON-SEVERE case
- > i) Use anti-pseudomonal B-lactam instead
(eg. IV Piperacillin/Tazobactam) + Macrolide (Clarithromycin or Azithromycin) OR Doxycycline
ii) IV Respiratory FQ (Levofloxacin
Treatment considerations for CAP
- Respiratory FQ not 1st line
- -> Increased adverse effects (ie. tendonitis, tendon rupture, neuropathy, arthropathy, QTc prolongation, CNS disturbances, hypoglycemia)
- -> Delay diagnosis for TB
- -> Resistance, preserve activity for other Gram (-)
Why consider adjunctive corticosteroid therapy?
Not routinely recommended
- Decrease inflammation in lungs
- May decrease length of stay & time to clinical stability
- Any impact is small & likely outweighed by increased hyperglycaemia
Monitoring of CAP therapy
1) Safety
- Adverse effects & renal function
2) Efficacy
- Clinical improvements expected in 48-72 hrs
- Should not escalate antibiotic therapy in 1st 72 hours
- Radiographic improvement lags behind, up to 4-6 weeks for resolution (Repeat only if clinical deterioration)
Treatment modifications for CAP
- Empiric coverage for MRSA/ Pseudomonas aeruginosa may be stopped in 48hrs if no MRSA or Pseudomonas aeruginosa
When to step down therapy?
- Hemodynamically stable
- Clinically improved/improving
- Afrebile >= 24hrs
- Normally functioning GIT
- Able to ingest PO
HOW to step down therapy
Positive cultures:
- Susceptibility results to guide selection of PO antibiotics
No positive cultures:
- Same antibiotic/ another antibiotic from same class
- Usually stop coverage for Burkholderia pseudomallei if organism is not cultured in sample
- Empiric therapy may be stopped in 48h if no MRSA/P. Aeruginosa & pt improving
