Shedding of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus from adult and pediatric bathers in marine waters
1 Department of Pediatrics and Department of Microbiology and Immunology, University of Miami, Miami, Florida 33130 USA
2 NSF-NIEHS Oceans and Human Health Center, University of Miami, Rosenstiel School for Marine and Atmospheric Sciences, 4600 Rickenbacker Causeway, EG 211 Key Biscayne, FL 33149 USA
3 NOAA Atlantic Oceanographic and Meteorological Laboratory, Miami, FL 33149 USA
4 Public Health and Health Education Programs, Northern Illinois University, DeKalb, IL USA
5 Miami-Dade County Health Department, 1725 NW 167 Street Miami, Florida 33056, USA
6 University of Miami, Department of Epidemiology and Public Health, 1120 NW 14th Street, Room 1049, Miller School of Medicine, Miami, FL 33136 USA
7 University of Miami, Department of Civil, Architectural, and Environmental Engineering, P.O. Box 248294, Coral Gables, Florida, 33124-0630, USA
BMC Microbiology 2011, 11:5 doi:10.1186/1471-2180-11-5Published: 6 January 2011
Staphylococcus aureus including methicillin resistant S. aureus, MRSA, are human colonizing bacteria that commonly cause opportunistic infections primarily involving the skin in otherwise healthy individuals. These infections have been linked to close contact and sharing of common facilities such as locker rooms, schools and prisons Waterborne exposure and transmission routes have not been traditionally associated with S. aureus infections. Coastal marine waters and beaches used for recreation are potential locations for the combination of high numbers of people with close contact and therefore could contribute to the exposure to and infection by these organisms. The primary aim of this study was to evaluate the amount and characteristics of the shedding of methicillin sensitive S. aureus, MSSA and MRSA by human bathers in marine waters.
Nasal cultures were collected from bathers, and water samples were collected from two sets of pools designed to isolate and quantify MSSA and MRSA shed by adults and toddlers during exposure to marine water. A combination of selective growth media and biochemical and polymerase chain reaction analysis was used to identify and perform limited characterization of the S. aureus isolated from the water and the participants. Twelve of 15 MRSA isolates collected from the water had identical genetic characteristics as the organisms isolated from the participants exposed to that water while the remaining 3 MRSA were without matching nasal isolates from participants. The amount of S. aureus shed per person corresponded to 105 to 106 CFU per person per 15-minute bathing period, with 15 to 20% of this quantity testing positive for MRSA.
This is the first report of a comparison of human colonizing organisms with bacteria from human exposed marine water attempting to confirm that participants shed their own colonizing MSSA and MRSA into their bathing milieu. These findings clearly demonstrate that adults and toddlers shed their colonizing organisms into marine waters and therefore can be sources of potentially pathogenic S. aureus and MRSA in recreational marine waters. Additional research is needed to evaluate recreational beaches and marine waters as potential exposure and transmission pathways for MRSA.