Community acquired pneumonia Flashcards
What is community acquired pneumonia?
acute infection of the pulmonary parenchyma acquired outside of the hospital
What is hospital acquired peumonia?
acute infection of the pulmonary parenchyma acquired outside of the hospital
What is ventilator associated pneumonia?
pneumonia acquired ≥ 48 hours after endotracheal intubation (ETT)
What are the risk factors for community acquire peumonia?
Older age
- Risk rises with age
- Age ≥ 65 is a/w increased severity
Chronic comorbidities
- COPD confers the highest risk for CAP hospitalisation
- Chronic lung disease (e.g. bronchiectasis, asthma)
- Chronic heart disease (particularly congestive heart failure [CHF])
- Stroke, DM, malnutrition, immunocompromise
Viral respiratory tract infection: Can lead to primary viral pneumonia, and predispose to secondary bacterial pneumonia (superinfection, most pronounced for influenza)
Impaired airway protection: Conditions that increase risk of aspiration of stomach contents and/or upper airway secretions, e.g. altered consciousness (stroke, seizure, anaesthesia, drug or alcohol use), dysphagia (oesophageal dysmotility)
Smoking and alcohol overuse
What is a pathogen to consider if patient has exposure to birds?
Chlamydia psittaci (if poultry, think avian influenza)
What is a pathogen to consider if patient has exposure to farm animals?
Coxiella burnetii (Q fever)
What is a pathogen to consider if patient stayed in a hotel or cruise the previous 2 weeks?
Legionella spp
What is a pathogen to consider if patient has structural lung disease?
Pseudomonas, Burkholderia cepacia, Staphylococcus aureus
Which are the common pathogens that cause pneumonia?
Typical bacteria
- Streptococcus pneumoniae (most common bacterial cause)
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Group A Streptococci
- Aerobic G- bacteria (e.g. Enterobacteriaceae such as Klebsiella or E coli)
- Microaerophilic bacteria and anaerobes (associated with aspiration)
Atypical bacteria (“atypical” due to (1) intrinsic resistance to beta lactams, and (2) inability to be visualised on Gram stain or cultured using traditional techniques)
- Legionella spp
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- Chlamydia psittaci
- Coxiella burnetii
Respiratory viruses
- Influenza A and B viruses
- Rhinoviruses
- Parainfluenza viruses
- Adenoviruses
- Respiratory syncytial virus (RSV)
- Coronaviruses (e.g. SARS, MERS-CoV)
What are the risk factors for having an MRSA as a cause for the pneumonia?
- Strongest risk factors: known MRSA colonisation, prior MRSA infection
- Other risk factors: recent antibiotic use (particularly receipt of intravenous antibiotics within the past three months), recent influenza-like illness (ask for preceding URTI s/s), the presence of empyema, necrotizing/cavitary pneumonia, and immunosuppression
What are the risk factors for having an Pseudomonas aeruginosa as a cause for the pneumonia?
known colonisation, prior infection with Pseudomonas, recent hospitalisation or antibiotic use, underlying structural lung disease (e.g. cystic fibrosis or advanced COPD [bronchiectasis]), and immunosuppression
what are the pathogens that cause a cavitating pneumonia?
Klebsiella, Staphylococcus aureus, TB
What are the symptoms of pneumonia?
Varies widely, ranging from mild pneumonia (fever, cough, SOB) to severe pneumonia (sepsis, respiratory distress)
Common symptoms: cough (+/- sputum production), SOB, pleuritic chest pain
- Mucopurulent sputum –> typical pathogens
- Scant or watery sputum –> atypical pathogen
- (rarely seen) rust-coloured sputum –> Strep pneumoniae
Fever (very common in general population, but can be absent in elderly), chills, fatigue, malaise, anorexia (LOA)
What are the signs of pneumonia?
- Inspection: tachypnoea, increased work of breathing
- Palpation: reduced chest expansion
- Percussion: dullness to percussion
- Auscultation: rales/crackles, rhonchi, reduced or bronchial breath sounds, increased vocal resonance
- tachycardia, sepsis (hypotension, altered mental state AMS), other organ dysfunction (renal, liver)
o S/s of pneumonia can also be subtle in patients with advanced age and/or impaired immune systems, and a higher degree of suspicion may be needed to make the diagnosis
What are the investigations required for pneumonia?
- FBC
- CRP/ Procalcitonin/ ESR
- Renal panel
- LFT
- CXR: possible findings include lobar consolidation, interstitial infiltrates, cavitation, pleural effusion (parapneumonic effusin), repeat 6 weeks after discharge TRO underlying branchial malignancy
- Blood c/s
- Legionella urine antigen test (UAT)
- Pneumococcal UAT
- mycoplasma serology
- flu pcr
- Pulse oximetry + ABG, if SaO2 < 94%
- HIV testing – pneumonia is a common initial presenting illness in patients previously undiagnosed
What is the CURB- 65 criteria?
Assign 1 point to each of: • Confusion (new disorientation to person, place, or time) • Urea (BUN) > 7 mmol/L • RR ≥ 30 bpm • BP (systolic < 90, or diastolic < 60) • Age ≥ 65
Total score
- 0-1: mild severity (mortality < 3%) –> outpatient
- 2: moderate severity (mortality ~9%) –>inpatient
- 3-5: severe (mortality 15-40%)–> ICU
What is the IDSA/ ATS criteria for severe CAP which indicates ICU admission?
Major criteria (1 required) • Respiratory failure requiring mechanical ventilation • Sepsis requiring vasopressor support
Minor criteria (3 required) (to identify sepsis that has not yet progressed to organ failure, because this group of patients will benefit from early ICU admission and abx) • Altered mental status (AMS) • Hypotension requiring fluid support • T < 36 • RR ≥ 30 • PaO2/FiO2 ≤ 250 • Urea (BUN) ≥ 7 mmol/L • WBC < 4000 cells/ mm3 • PLT < 100 000 cells/ mm3 • Multilobar infiltrates
What is the treatment for CAP?
First-line: IV co-amoxiclav (Augmentin) + PO clarithromycin
- Augmentin –> broad-spectrum
- Clarithromycin –> atypical
Second-line: IV ceftriaxone + PO clarithromycin
- Ceftriaxone –> PCP, Salmonellosis (suspect in query HIV patient)
What is the treatment for severe CAP/ immunocompromised?
First line: IV penicillin + IV ceftazidime + IV azithromycin
- Penicillin –> Strep pneumoniae
- Ceftazidime –> Burkholderia (melioidosis), GNR cover
- Azithromycin –> atypical
Second-line: IV ceftazidime + PO levofloxacin
- Levofloxacin is respiratory fluoroquinolone –> Strep pneumoniae
- Note that fluoroquinolone use is not favoured as it can lead to TB resistance to this important second-line anti-TB agent
What is the treatment for HAP/ VAP?
First-line: IV pip/tazo + IV vancomycin [25 mg/kg (once, and if severe illness, continue at maintenance dose 15 mg/kg Q12h)]
- Pip/tazo –> Pseudomonas cover
- Vancomycin –> MRSA cover
Second-line: IV ceftazidime + IV vancomycin [25 mg/kg (once, and if severe illness, continue at maintenance dose 15 mg/kg Q12h)] + IV amikacin STAT
What is the treatment for aspiration pneumonia
First-line: IV co-amoxiclav (Augmentin)
- Augmentin –> BSA w/ anaerobic cover
- Second-line: IV ceftriaxone + PO metronidazole
What is parapneumonic effusion and empyema? How do you tell if it is complicated or uncomplicated?
pleural effusion that develops adjacent to bacterial pneumonia
- Uncomplicated -> exudative effusion w/ neutrophilic influx (not infected) -> Gram +ve organisms, pH < 7.20, glucose < 3.3mmol/L (60 mg/dL) on pleural fluid analysis
- Complicated -> bacterial invasion of pleural space (infected) –> Gram stain negative (no bacterial growth NBG), pH normal > 7.2, glucose normal > 3.3 on pleural fluid analysis
how to treat parapneumonic effusion and empyema?
(For all patients) Empiric IV antibiotics. Cover anaerobes (e.g. Augmentin) while pending results.
Uncomplicated- observation, serial CXR or U/S to assess response to abx
Complicated/ empyema
• Tube thoracostomy (chest tube drainage) -> drain effusion as it is unlikely to resolve spontaneously
• Consider VATS (video-assisted thoracoscopic surgery) with debridement if -> multiple loculations, thickened pleura
• If empyema, 4-6 weeks of antibiotics may be needed
