ABSTRACT
BACKGROUND: Little is known about the occurrence and epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in public transportation in the United States. This research sought to determine the background prevalence and phenotypic and genotypic characteristics of MRSA strains circulating on buses from a large, metropolitan transportation agency. METHODS: Electrostatic wipes were used to collect 237 surface samples from 40 buses randomly selected from July-October 2010. Six samples were collected from each bus immediately postservice and before any cleaning and disinfection. Positive isolates were analyzed for antibiotic resistance, staphylococcal cassette chromosome mec (SCCmec) type, and pulsed-field gel electrophoresis; and potential epidemiologic factors were examined. RESULTS: Of the buses, 68% (27/40) were contaminated with S aureus, and 63% (25/40) were contaminated with MRSA. Seats and seat rails were the surfaces most frequently contaminated, followed by the back door and stanchions. Most (62.9%) of the MRSA isolates were classified as community-associated MRSA clones (SCCmec type IV), and 22.9% were health care-associated MRSA clones (SCCmec type II). Of the MRSA strains, 65% (5/20) were multidrug resistant. CONCLUSION: MRSA was frequently isolated from commonly touched surfaces in buses serving both hospital and community routes. Phenotypic and genotypic analysis demonstrated that buses may be effective mixing vessels for MRSA strains of both community and health care-associated origin.
Subject(s)
Methicillin-Resistant Staphylococcus aureus/isolation & purification , Motor Vehicles , Staphylococcal Infections/epidemiology , Anti-Bacterial Agents/pharmacology , Bacterial Typing Techniques , Drug Resistance, Multiple, Bacterial/genetics , Electrophoresis, Gel, Pulsed-Field , Female , Genotype , Humans , Methicillin/pharmacology , Methicillin Resistance/genetics , Methicillin-Resistant Staphylococcus aureus/genetics , Microbial Sensitivity Tests , Phenotype , Prevalence , Staphylococcal Infections/microbiology , Staphylococcal Infections/transmissionABSTRACT
Pseudomonas aeruginosa is an important opportunistic pathogen in recreational waters and the primary cause of hot tub folliculitis and otitis externa. The aim of this surveillance study was to determine the background prevalence and antimicrobial resistance profile of P. aeruginosa in swimming pools and hot tubs. A convenience sample of 108 samples was obtained from three hot tubs and eight indoor swimming pools. Water and swab samples were processed using membrane filtration, followed by confirmation with polymerase chain reaction. Twenty-three samples (21%) were positive for P. aeruginosa, and 23 isolates underwent susceptibility testing using the microdilution method. Resistance was noted to several antibiotic agents, including amikacin (intermediate), aztreonam, ceftriaxone, gentamicin, imipenem, meropenem (intermediate), ticarcillin/clavulanic acid, tobramycin (intermediate), and trimethoprim/sulfamethoxazole. The results of this surveillance study indicate that 96% of P. aeruginosa isolates tested from swimming pools and hot tubs were multidrug resistant. These results may have important implications for cystic fibrosis patients and other immune-suppressed individuals, for whom infection with multidrug-resistant P. aeruginosa would have greater impact. Our results underlie the importance of rigorous facility maintenance, and provide prevalence data on the occurrence of antimicrobial resistant strains of this important recreational water-associated and nosocomial pathogen.
