ICU · Infectious Diseases

Acute severe community-acquired pneumonia: Pseudomonas pneumonia

Also known as Pseudomonas aeruginosa pneumonia · Pseudomonas CAP · Antipseudomonal therapy · Nosocomial Pseudomonas pneumonia · MDR Pseudomonas pneumonia

Pseudomonas aeruginosa is an aerobic Gram-negative bacillus — an opportunistic, water-borne pathogen that forms biofilms and thrives in moist environments and on indwelling devices. It is a rare cause of community-acquired pneumonia (CAP, <1% of uncomplicated CAP) but a major cause of hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), and a feared pathogen in patients with structural lung disease (bronchiectasis, cystic fibrosis), immunocompromise/neutropenia, and prior broad-spectrum antibiotic exposure. Clinical course is severe and rapidly progressive, with cure in the classic bacteraemia series only half as likely when the first antibiotic is the wrong one. Diagnosis rests on sputum or bronchoalveolar-lavage (BAL) culture with Gram stain showing Gram-negative bacilli. Management mandates an anti-pseudomonal beta-lactam (piperacillin-tazobactam, cefepime, ceftazidime, or a carbapenem) plus a second active agent (aminoglycoside or fluoroquinolone) for severe disease, then de-escalation to monotherapy at 48-72 h once susceptibilities return.

Checked against its sources on 23 Sept 2026