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Human exposure to antimicrobial-resistant bacteria may result in the transfer of resistance to commensal or pathogenic microbes present in the gastrointestinal tract, which may lead to severe health consequences and difficulties in treatment of future bacterial infections. It was hypothesized that the recreational waters from beaches represent a source of antimicrobial-resistant Escherichia coli for people engaging in water activities.To describe the occurrence of antimicrobial-resistant E coli in the recreational waters of beaches in southern Quebec.Sampling occurred over two summers; in 2004, 674 water samples were taken from 201 beaches, and in 2005, 628 water samples were taken from 177 beaches. The minimum inhibitory concentrations of the antimicrobial-resistant E coli isolates against a panel of 16 antimicrobials were determined using microbroth dilution.For 2004 and 2005, respectively, 28% and 38% of beaches sampled had at least one water sample contaminated by E coli resistant to one or more antimicrobials, and more than 10% of the resistant isolates were resistant to at least one antimicrobial of clinical importance for human medicine. The three antimicrobials with the highest frequency of resistance were tetracycline, ampicillin and sulfamethoxazole.The recreational waters of these beaches represent a potential source of antimicrobial-resistant bacteria for people engaging in water activities. Investigations relating the significance of these findings to public health should be pursued.L’exposition humaine à des bactéries résistant aux antimicrobiens peut provoquer le transfert de la résistance à des microbes commensaux ou pathogènes présents dans le tube digestif, ce qui peut avoir de graves conséquences sur la santé et compliquer le traitement de futures infections bactériennes. On a soulevé l’hypothèse que les eaux de baignade des plages représentent une source d’infection à l’Les chercheurs ont procédé à l’échantillonnage sur deux étés. En 2004, ils ont prélevé 674 échantillons d’eau sur 201 plages, et en 2005, 628 échantillons d’eau sur 177 plages. Ils ont établi les concentrations inhibitrices minimales des isolats d’En 2004 et en 2005, respectivement, 28 % et 38 % des plages échantillonnées comptaient au moins un échantillon d’eau contaminée par l’Les eaux de baignade de ces plages représentent une source potentielle de bactéries résistant aux antimicrobiens pour les personnes qui s’adonnent à des activités aquatiques. Il faudrait poursuivre les recherches sur la signification de ces observations en matière de santé publique.

BACKGROUND: In 2004, an outbreak of the USA300 strain of methicillin-resistantStaphylococcus aureus(MRSA) was identified in persons with histories of homelessness, illicit drug use or incarceration in the Calgary Health Region (Calgary, Alberta). A prevalence study was conducted to test the hypotheses for factors associated with USA300 colonization or infection.METHODS: Participants were recruited at sites accessed by this marginalized population. Health care staff administered a questionnaire and collected crack pipes and nasal, axillary and skin infection swabs. Pipes and swabs were cultured according to standard techniques. MRSA isolates were further characterized by polymerase chain reaction (mecA, Panton-Valentine leukocidin and Staphylococcal cassette chromosomemec) and typing methods (pulsed-field gel electrophoresis, staphylococcal protein A typing and multilocus sequence typing). Colonization or infection was determined by having any one of nasal, axillary, skin infection or pipe swabs positive for USA300. Colonized participants had one or more nasal, axillary or pipe swab positive for USA300; infected participants had one or more skin infection swab positive for USA300.RESULTS: The prevalence of USA300 colonization or infection among 271 participants was 5.5% (range 3.1% to 9.0%). USA300 cases were more likely to report manipulation of skin infections (OR 9.55; 95% CI 2.74 to 33.26); use of crack pipes was not significant despite identification of the USA300 strain on two of four crack pipes tested. USA300 cases were more likely to report drug use between sex trade workers and clients (OR 5.86; 95% CI 1.63 to 21.00), and with casual sex partners (OR 5.40; 95% CI 1.64 to 17.78).CONCLUSION: Ongoing efforts to promote the appropriate treatment of skin infections in this population are warranted. The association of USA300 colonization or infection and drug use with sexual partners suggest a role for sexual transmission of the USA300 strain of MRSA.