Characterization of Methicillin-resistant Staphylococcus aureus Isolates from Fitness Centers in Memphis Metropolitan Area, USA

Indoor skin-contact surfaces of public fitness centers may serve as reservoirs of potential human transmission of methicillin-resistant Staphylococcus aureus (MRSA). We found a high prevalence of multi-drug resistant (MDR)-MRSA of CC59 lineage harboring a variety of extracellular toxin genes from surface swab samples collected from inanimate surfaces of fitness centers in Memphis metropolitan area, USA. Our findings underscore the role of inanimate surfaces as potential sources of transmission of MDR-MRSA strains with considerable genetic diversity. 3 Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), contagion with varied severity ranging from superficial skin and soft tissue infections to life-threatening conditions, including endocarditis, bacteremia, and necrotizing pneumonia, has emerged as the major cause of human staphylococcal infections. 1, 2 Recent literature reported the diversity in the clonal and molecular characteristics of CA-MRSA, making it almost indistinguishable from its healthcare-associated counterpart (HA-MRSA). 3 Inanimate surfaces may serve as environmental reservoirs for CA-MRSA transmission; and for public fitness and sports facilities where skin contact is common, this amounts to be a matter of grave concern. 1 However, the information on the molecular characteristics of the environmental MRSA isolates from fitness centers and sports facilities is limited, and therefore warrants more investigation. In a recent metagenomics-based study reporting the overall bacterial diversity of the common fitness center surfaces revealed an abundance of operation taxonomic units (OTUs) attributable to Staphylococcus species. 4 In this brief communication, we report the prevalence, multi-drug resistance, and molecular characteristics of the MRSA isolates from fitness centers in Memphis metropolitan area in Tennessee. METHODS The sample collection procedures have been described in a previous study. 4 Briefly, a total of 32 samples were collected from the skin-contact surfaces on exercise equipment (nautilus machine, stationary bike, treadmill, elliptical machine, power strider, and leg press), dumbbell, toilet handles, and handrails on stairs from four membership-based fitness centers around the Memphis metropolitan area. The presumptive S. aureus colonies were isolated and identified by 4 plating on BBL TM CHROMagar TM MRSA plates (BDCM) (BD Diagnostics, USA) followed by sub-culturing on Mannitol Salt agar (MSA) (Thermo Scientific™ Remel™ MSA, USA), and by coagulase and catalase tests. Further, the molecular identification of the cultures was done by amplifying staphylococcal 16S rRNA gene, as well as mecA, femA, and femB genes associated with the methicillin resistance property of S. aureus (details of the methods are provided in the Supplementary Information). Antimicrobial susceptibility testing was performed using the Sensititre® microbroth dilution …