Fitness costs associated with carriage of a large staphylococcal plasmid are reduced by subinhibitory concentrations of antiseptics. Issue 4 (13th February 2020)

• Record Type: Journal Article
• Authors: LaBreck, Patrick T.; Merrell, D. Scott
• Is Part Of: MicrobiologyOpen. Volume 9:Issue 4(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-13
• Subjects: antibiotic resistance -- bacterial plasmids -- mobile genetic elements -- Staphylococcus; Microbiology -- Periodicals; 579
• DOI: 10.1002/mbo3.1005
• Languages: English
• ISSNs: 2045-8827

Abstract

Abstract: Staphylococcus aureus carries a collection of mobile genetic elements that often harbor virulence and antimicrobial resistance genes. Since the introduction of antibiotics, plasmids have become a major genetic element responsible for the distribution of antimicrobial resistance. Under antimicrobial selection, resistance plasmids are maintained within bacterial populations as a means to ensure survival. However, in the absence of selection, large plasmids can be lost due to the fitness costs associated with harboring these genetic elements. pC02 is a previously identified multidrug resistance, conjugative plasmid that is found in S. aureus . In addition to antibiotic resistance, pC02 also carries genes known to be associated with antiseptic resistance. Among these, we previously characterized the contribution of qacA to pC02 mediated reduced chlorhexidine susceptibility. Herein, we demonstrate that pC02 also mediates triclosan resistance, likely due to the presence of fabI, a known triclosan resistance gene. Moreover, we demonstrate that conjugative transfer of pC02 increases triclosan resistance in recipient cells. Competition assays demonstrated a fitness cost associated with carriage of the large pC02 plasmid. However, subinhibitory concentrations of either chlorhexidine or triclosan abrogated this fitness cost. Given the widespread use of these antiseptics, both of which accumulate in wastewater and other environmental reservoirs, indiscriminate use of antiseptics likely imposes a constant selective pressure that promotes maintenance of antimicrobial resistance factors within S. aureus . Abstract : Pathogenic bacteria often carry large plasmids that contain multiple resistance genes; individually, these elements coselect for additional resistance genes that are genetically linked by the plasmid. In this short communication, we demonstrate increased triclosan resistance can be conjugatively transferred in Staphylococcus aureus . Furthermore, in a competition assay, we show subinhibitory concentrations of antiseptics abrogate the fitness cost of a large multidrug resistance plasmid in S. aureus, thus coselecting for the numerous antimicrobial resistance genes present on the plasmid.