Macrolides, Tetracyclines & Oxazolidinones — Atypicals, MRSA & VRE

Meet the patient

A 67-year-old man, day 12 of an ICU admission for necrotising pancreatitis, develops a new fever with two-of-two peripheral blood cultures growing vanA Enterococcus faecium (VRE) — in published VRE-bacteraemia series the isolates are E. faecium, with linezolid and daptomycin the two primary treatment options. His home medications include sertraline 100 mg daily and he has been receiving tramadol for breakthrough pain. His platelets are 145, falling from a baseline of 220.^[14]

Three traps hide in this vignette, and each is exam gold. The organism is VRE, so linezolid or daptomycin — but linezolid-serotonergic drug combinations are the most-reported source of linezolid-associated serotonin syndrome in post-marketing surveillance, and sertraline plus tramadol plus linezolid is a serotonin-syndrome recipe. The platelets are already falling, and linezolid-induced thrombocytopenia is significantly associated with treatment duration of at least 14 days, shock and renal impairment. And the infection is bacteraemic rather than pneumonic — the setting where daptomycin dosing matters most, with higher-dose daptomycin associated with better survival. Choose with the toxicities in mind, and you pass the stem.^[11][13][15]

References19ShowHide

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