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Low-severity community-acquired pneumonia — MSRA MCQ

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HardInfectious DiseasesLow-severity community-acquired pneumoniaMSRA

A 58-year-old man is assessed in general practice with a 3-day history of fever, purulent sputum and right-sided pleuritic chest pain. He is orientated, drinking normally and able to take oral medicines. His temperature is 38.1°C, respiratory rate 23 breaths/minute, pulse 98 beats/minute, blood pressure 126/72 mmHg and oxygen saturation 96% on room air. There are focal right basal crackles and bronchial breathing. You diagnose community-acquired pneumonia. He had anaphylaxis 20 minutes after amoxicillin 4 years ago. He takes simvastatin 40 mg nightly and ramipril. He has no recent antibiotic exposure, hospital admission, immunosuppression, pregnancy risk or symptoms suggesting sepsis. His eGFR is 72 mL/minute/1.73 m². Which is the most appropriate management today?

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Correct answer: B — Prescribe oral doxycycline 200 mg on day 1, then 100 mg once daily for 4 further days, with primary care safety-netting

This man has low-risk community-acquired pneumonia: his CRB65 score is 0 because he has no confusion, respiratory rate is below 30 breaths/minute, blood pressure is not low and he is younger than 65 years. NICE recommends primary care-led management with safety-netting for CRB65 score 0, provided clinical assessment does not indicate sepsis, cardiorespiratory failure or another reason for admission. He can take oral treatment. Amoxicillin is first-line for low-severity disease, but his rapid-onset anaphylaxis is a convincing immediate penicillin hypersensitivity reaction, so re-exposure is inappropriate. NICE lists doxycycline and clarithromycin as alternative oral regimens when penicillin cannot be used. However, clarithromycin and erythromycin interact with simvastatin; if either macrolide is essential, simvastatin should be stopped during treatment. The proposed macrolide options explicitly continue simvastatin and are therefore inappropriate as written. Erythromycin is additionally the NICE-listed macrolide option in pregnancy, which is not relevant here. Doxycycline is a guideline-listed alternative, has the specified 5-day regimen, avoids the macrolide–simvastatin interaction, and is suitable for outpatient management in this clinically stable patient.

Reference: NICE NG250: Pneumonia: diagnosis and management — Recommendations (September 2025) — https://www.nice.org.uk/guidance/ng250/chapter/Recommendations NHS Specialist Pharmacy Service: Managing interactions between macrolides and statins (2023) — https://www.sps.nhs.uk/articles/managing-interactions-between-macrolides-and-statins/