Sarah R. DeenyColin J. WorbyOlga Tosas AuguetBen S. CooperJonathan EdgeworthBarry CooksonJulie V. RobothamPublic Health EnglandHarvard School of Public HealthGuy's and St Thomas' NHS Foundation TrustUniversity of OxfordUCL2018-11-232018-11-232015-12-01The Journal of antimicrobial chemotherapy. Vol.70, No.12 (2015), 3366-3378146020912-s2.0-84949574795https://repository.li.mahidol.ac.th/handle/123456789/36245© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. OBJECTIVES: The objectives of this study were to estimate the relative transmissibility of mupirocin-resistant (MupR) and mupirocin-susceptible (MupS) MRSA strains and evaluate the long-term impact of MupR on MRSA control policies.METHODS: Parameters describing MupR and MupS strains were estimated using Markov chain Monte Carlo methods applied to data from two London teaching hospitals. These estimates parameterized a model used to evaluate the long-term impact of MupR on three mupirocin usage policies: 'clinical cases', 'screen and treat' and 'universal'. Strategies were assessed in terms of colonized and infected patient days and scenario and sensitivity analyses were performed.RESULTS: The transmission probability of a MupS strain was 2.16 (95% CI 1.38-2.94) times that of a MupR strain in the absence of mupirocin usage. The total prevalence of MupR in colonized and infected MRSA patients after 5 years of simulation was 9.1% (95% CI 8.7%-9.6%) with the 'screen and treat' mupirocin policy, increasing to 21.3% (95% CI 20.9%-21.7%) with 'universal' mupirocin use. The prevalence of MupR increased in 50%-75% of simulations with 'universal' usage and >10% of simulations with 'screen and treat' usage in scenarios where MupS had a higher transmission probability than MupR.CONCLUSIONS: Our results provide evidence from a clinical setting of a fitness cost associated with MupR in MRSA strains. This provides a plausible explanation for the low levels of mupirocin resistance seen following 'screen and treat' mupirocin usage. From our simulations, even under conservative estimates of relative transmissibility, we see long-term increases in the prevalence of MupR given 'universal' use.Mahidol UniversityMedicineArticleSCOPUS10.1093/jac/dkv249