Introduction
Evolving bacterial resistance to antimicrobial agents, one of the ten
most critical public health threats according to the World Health
Organization, demands immediate action[1]. Antimicrobial cycling or
rotation is among the multitude of initiatives tried to streamline
antibiotic prescribing, and fall within the umbrella term of
antimicrobial stewardship. Cycling or rotation incurs scheduled shifts
in empirical antibiotic treatment protocols, switching periodically
between antimicrobial agents of similar spectrum. This practice is often
adopted in high-risk settings such as Intensive Care Units and relies
more or less on an intuitive perception that such scheduled rotations of
antimicrobial agents could alter selective pressures on bacterial
populations accordingly and thus stem the onset of resistant strains.
The concept was probably further developed in the 90’s when Gerding et
al reported improvements in aminoglycoside resistance rates as a result
of changes in the type of predominant aminoglycoside use[2][3].
However, mathematical models have challenged the strategy’s presumable
effectiveness by predicting that interventions which favoured a more
heterogeneous antimicrobial use would be more successful in bacterial
resistance control[4][5][6]. According to a 2006 systematic
literature review very few studies met inclusion criteria and lack of
rigorousness in study designs for those finally included was
insufficient to draw safe inferences[7] A meta-analysis following
almost ten years later suggested potential benefits by the application
of the particular strategy without, however, performing an in-depth
evaluation of the available studies[8].
We aim to provide an updated review and evaluation of the evidence with
regard to the efficacy of antimicrobial cycling on bacterial resistance
control within hospital settings. Our study is a composite element of a
wider project with the objective to assess the impact of different
antimicrobial stewardship initiatives on bacterial resistance rates
which has led to the publication of two additional papers discussing the
role of antimicrobial restrictions[9] and prospective audit with
feedback[10].