Community Acquired Pneumonia
OVERVIEW
- single organism (often)
- Streptococcus pneumonia (most common organism)
- other causes: Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella, Haemophilus influenzae (in COPD)
CLINICAL FEATURES
- cough, fever, shortness of breath, pleuritic chest pain, fatigue, sputum (rust coloured classically suggests pneumococcus)
- tachypnea, hypoxia, respiratory distress, increased work of breathing, bronchial breath sounds, crackles
Risk factors for Severe Infection
- elderly
- co-morbidity
- smoking
- alcohol abuse
- failure to contain infection @ entry site
- immunosuppression
- genetic polymorphism
ASSOCIATIONS
- alcoholism — Streptococcus pneumoniae, anaerobes, Gram negatives such as Klebsiella pneumonia, tuberculosis
- COPD/ smoker — Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis
- nursing home resident — Streptococcus pneumoniae, Gram negatives, Haemophilus influenzae, S. aureus, Chlamydophila pneumoniae consider tuberculosis and anaerobes (but less common)
- poor dental hygiene — anaerobes
- bat/ cave exposure — Histoplasma capsulatum
- bird exposure — Chlamydophila psitacci, Cryptococcus neoforms, Histoplasma capsulatum
- rabbit exposure — Franciscella tularensis
- exposure to farm animals or parturient cats — Coxiella burnetti (Q fever)
- post-infuenza — S. pneumoniae, S. aureus
- brochiectasis, cystic fibrosis — Pseudomonas aeroginosa, S. pneumoniae, Burkholderia cepacia
- sickle cell disease, asplenia — S. pneumoniae, H. influenzae
- Suspected bioterrorism — Anthrax
- Tropical Australia — melioidosis, Acinetobacter
- Potting mix — Legionella longbeachae
- Travel to Asia — SARS, tuberculosis, meliodosis
INVESTIGATIONS
- CXR
- CT: helps identify loculated effusion, helpful in non-responders
- blood culture: only 15% positive
- sputum gram stain: can help with defining predominate organisms
- sputum culture: use if drug-resistant or unusual organism suspected
- ABG: hypercapnia, hypoxemia
- serology: legionella, Chlamydia, mycobacterium, viruses (requires acute and convalescent titers -> not usually recommended)
- legionella urinary antigen: sensitivity 60%, specific to serogroup 1 (quadravalent assay now available)
- pneumococcal antigen: sensitivity 70-100%, specificity 80%, false positives if has had recent pneumococcal infection
RISK STRATIFICATION
- multiple scores have been looked to predict severity and outcome: Pneumonia severity score, CURB-65 score, SMART COP, CAP PIRO
SMART COP
- Australian Community Acquired Pneumonia Study -> looked at variable predicting the requirement for intensive respiratory or vasoactive support
- initially 882 prospective episodes looked at -> points based severity tool designed -> validated in 7464 patients
- more sensitive than CURB-65 or IRVS
- score of >/= 4 correlated with a 1/3 chance of requiring intensive respiratory or vasoactive support
S – systolic BP < 90mmHg
M – multilobe infiltrate
A – albumin < 35g/L
R – RR (age adjusted < 50yrs >25/min, > 50yrs >30/min)
T – tachycardia > 125/min
C – confusion (acute onset)
O – oxygenation (age adjusted: SpO2 < 93%, PaO2 < 70mmHg, PF < 333mmHg)
P – pH < 7.35
MANAGEMENT
- antibiotics within 4 hours
Non-tropical
- Pneumococcus + atypical cover
- mild: amoxicillin + clarithromycin PO
- moderate: penicillin IV + clarithromycin PO (+gentamicin if risk factors)
- severe: ceftriaxone + clarithromycin IV
Tropical
- need to cover Burkholderia pseudomallei and Acinetobacter baumannii
- meropenem/imipenem + azithromycin/erthyromycin
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
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