Tractable targets for meropenem-sparing antimicrobial stewardship interventions

BACKGROUND: As meropenem is a restricted antimicrobial, lessons learned from its real-life usage will be applicable to antimicrobial stewardship (AMS) more generally. OBJECTIVES: To retrospectively evaluate meropenem usage at our institution to identify targets for AMS interventions. METHODS: Patients receiving meropenem documented with an ‘alert antimicrobial’ form at two tertiary care UK hospitals were identified retrospectively. Clinical records and microbiology results were reviewed. RESULTS: A total of 107 adult inpatients receiving meropenem were identified. This was first-line in 47% and escalation therapy in 53%. Source control was required in 28% of cases after escalation, for predictable reasons. Those ultimately requiring source control had received more prior antimicrobial agents than those who did not (P = 0.03). Meropenem was rationalized in 24% of cases (after median 4 days). Positive microbiology enabled rationalization (OR 12.3, 95% CI 2.7–55.5, P = 0.001) but rates of appropriate sampling varied. In cases with positive microbiology where meropenem was not rationalized, continuation was retrospectively considered clinically and microbiologically necessary in 8/40 cases (0/17 empirical first-line usage). Rationalization was more likely when meropenem susceptibility was not released on the microbiology report (OR 5.2, 95% CI 1.3–20.2, P = 0.02). Input from an infection specialist was associated with a reduced duration of meropenem therapy (P < 0.0001). Early review by an infection specialist has the potential to further facilitate rationalization. CONCLUSIONS: In real-life clinical practice, core aspects of infection management remain tractable targets for AMS interventions: microbiological sampling, source control and infection specialist input. Further targets include supporting rationalization to less familiar carbapenem-sparing antimicrobials, restricting first-line meropenem usage and selectively reporting meropenem susceptibility.