skip to main content

Pseudomonas HAP Risk Factors — SCE Infectious Diseases MCQ

Instant feedback + full explanation. One question, done properly.

EasyAntimicrobial StewardshipPseudomonas HAP Risk FactorsSCE Infectious Diseases

A 50-year-old man with COPD develops hospital-acquired pneumonia on day 8 of admission. He has been on IV Co-amoxiclav for 5 days for his initial pneumonia. His new sputum culture grows Pseudomonas aeruginosa. The initial Co-amoxiclav does not cover Pseudomonas. What is the most important risk factor for Pseudomonas HAP in this scenario?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Prior antibiotic exposure — recent broad-spectrum antibiotic use is the strongest risk factor for selecting Pseudomonas aeruginosa in hospital-acquired pneumonia

Prior antibiotic exposure is the strongest independent risk factor for Pseudomonas HAP. Broad-spectrum antibiotics suppress competing normal flora, allowing Pseudomonas (which is intrinsically resistant to many first-line antibiotics) to colonise and subsequently cause infection. Other risk factors include: prolonged hospitalisation (>5 days), ICU admission, mechanical ventilation, structural lung disease (bronchiectasis, CF, COPD), and prior Pseudomonas colonisation. This case illustrates the importance of antibiotic stewardship — unnecessary broad-spectrum use drives MDR organism selection.

Reference: NICE NG139 2019 – HAI; ERS/ESICM 2017 – HAP/VAP