MRSA Bacteraemia First-Line Antibiotic — FRCA Final MCQ

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ModerateIntensive Care MedicineMRSA Bacteraemia First-Line AntibioticFRCA Final

A 55-year-old man (ASA III) develops a wound infection 5 days after emergency laparotomy. The wound is opened, debrided, and packed. He develops sepsis requiring ICU admission. Blood cultures grow MRSA. According to NICE, what is the first-line antibiotic for MRSA bacteraemia?

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Correct answer: D — Daptomycin

NICE and PHE guidelines recommend vancomycin as first-line treatment for MRSA bacteraemia (with doses guided by therapeutic drug monitoring, trough level 15-20 mg/L for serious infections). Flucloxacillin is only effective against MSSA. Linezolid has good tissue penetration but is bacteriostatic (not bactericidal) and is generally reserved for pneumonia or when vancomycin fails. Daptomycin is an alternative for MRSA bacteraemia (especially with vancomycin-intermediate S. aureus) but is inactivated by surfactant so CANNOT be used for pneumonia. Duration: minimum 14 days for uncomplicated bacteraemia, longer if endocarditis or deep-seated infection.

Reference: NICE – 2022 – MRSA management; PHE – 2019 – MRSA bacteraemia guidelines