10.26091/ESRNZ.8062865.v1 Glen P. Carter Glen P. Carter Mark Schultz Mark Schultz Sarah L. Baines Sarah L. Baines Anders Gonçalves da Silva Anders Gonçalves da Silva Helen Heffernan Helen Heffernan Audrey Tiong Audrey Tiong Peter H. Pham Peter H. Pham Ian R. Monk Ian R. Monk Timothy P. Stinear Timothy P. Stinear Benjamin P. Howden Benjamin P. Howden Deborah A. Williamson Deborah A. Williamson Topical antibiotic use coselects for the carriage of mobile genetic elements conferring resistance to unrelated antimicrobials in Staphylococcus aureus Institute of Environmental Science and Research 2019 Fusidic acid mupirocin Staphylococcus aureus Topical antibiotics Coselection Multidrug resistance Plasmids Mupirocin Resistance Evolution Chlorhexidine Bacteremia Emergence New Zealand Microbiology Microbial Genetics 2019-05-02 04:24:57 Journal contribution https://research.esr.cri.nz/articles/journal_contribution/Topical_antibiotic_use_coselects_for_the_carriage_of_mobile_genetic_elements_conferring_resistance_to_unrelated_antimicrobials_in_Staphylococcus_aureus/8062865 Topical antibiotics, such as mupirocin and fusidic acid, are commonly used in the prevention and treatment of skin infections, particularly those caused by staphylococci. However, the widespread use of these agents is associated with increased resistance to these agents, potentially limiting their efficacy. Of particular concern is the observation that resistance to topical antibiotics is often associated with multidrug resistance, suggesting that topical antibiotics may play a role in the emergence of multidrug-resistant (MDR) strains. New Zealand (NZ) has some of the highest globally recorded rates of topical antibiotic usage and resistance. Using a combination of Pacific Biosciences single-molecule real-time (SMRT) whole-genome sequencing, Illumina short-read sequencing, and Bayesian phylogenomic modeling on 118 new multilocus sequence type 1 (ST1) community Staphylococcus aureus isolates from New Zealand and 61 publically available international ST1 genome sequences, we demonstrate a strong correlation between the clinical introduction of topical antibiotics and the emergence of MDR ST1 S. aureus. We also provide in vitro experimental evidence showing that exposure to topical antibiotics can lead to the rapid selection of MDR S. aureus isolates carrying plasmids that confer resistance to multiple unrelated antibiotics, from within a mixed population of competitor strains. These findings have important implications regarding the impact of the indiscriminate use of topical antibiotics.