Systematic review of the effects of antimicrobial cycling on bacterial resistance rates within hospital settings

Aim: Antimicrobial resistance is an evolving phenomenon with alarming public health consequences. Antibiotic cycling is a widely known antimicrobial stewardship initiative which encompasses periodical shifts in empirical treatment protocols with the aim of limiting selective pressures on bacterial populations. We present a review of the evidence regarding the actual impact of antimicrobial cycling on bacterial resistance control within hospitals. Methods: A systematic literature review was conducted using the PubMed/MedLine, Embase, CINAHL Plus and Global Health databases. Results: A systematic search process retrieved a sole randomised study, and so we broadened inclusion criteria to encompass quasi-experimental designs. Fifteen studies formed our dataset including seven prospective trials and eight before-and-after studies. Nine studies evaluated cycling versus a control group and produced conflicting results whilst three studies compared cycling with antibiotic mixing, with none of the strategies appearing superior. The rest evaluated resistance dynamics of each of the on-cycle antibiotics with contradictory findings. Research protocols differed in parameters such as the cycle length, the choice of antibiotics, the opportunity to de-escalate to narrow-spectrum agents and the measurement of indicators of collateral damage. This limited our ability to evaluate the replicability of findings and the overall policy effects. Conclusions: Dearth of robust designs and standardised protocols limits our ability to reach safe conclusions. Nonetheless, in view of the available data we find no reason to believe that cycling should be expected to improve antibiotic resistance rates within hospitals.