Oxacillin plus ertapenem combination therapy leads to rapid blood culture clearance and positive outcomes among patients with persistent MSSA bacteraemia: a case series

BACKGROUND: Bloodstream infections caused by MSSA are associated with significant morbidity and mortality. Traditional treatment of MSSA bacteraemia includes an IV antistaphylococcal β-lactam and surgical source control when indicated. OBJECTIVES: To evaluate the time to blood culture clearance as well as in-hospital and 90 day mortality in patients with persistent MSSA bacteraemia treated with combination antistaphylococcal penicillin plus carbapenem therapy. METHODS: Consecutive patients with persistent MSSA bacteraemia treated with combination therapy were identified by study investigators and reviewed by independent clinicians. The decision to initiate combination therapy was made by the consulting clinician or by the institution’s multidisciplinary endocarditis team. RESULTS: Among 10 patients with a median of 5 days of persistent MSSA bacteraemia, treatment with an antistaphylococcal penicillin plus carbapenem led to sterilization of blood cultures in all patients. Blood culture clearance occurred in a median of 1 day and patients received a median of 6 days of combination treatment. Four of seven patients who underwent source control of their primary site of infection cleared their bacteraemia on combination therapy prior to the surgical intervention. All patients survived to hospital discharge and 90 days post-discharge. CONCLUSIONS: These data extend prior findings and provide further evidence that suggests the potential benefits of combination therapy among patients with persistent MSSA bacteraemia.