Methicillin Resistant Staphylococcus aureus in Surface Water in Karaj

Staphylococcus aureus is known as a bacterial pathogen responsible for a wide range of human infections in hospitals and communities that are difficult to treat. Surface water could be a possible source of methicillin resistant S. aureus strains in communities and may have a significant role in development and dissemination of antibiotic resistance. In this study for the first time in Iran, during 2013 we evaluated the prevalence, antibiotic resistance patterns and SCCmec types of MRSA strains isolated from two urban streams in Karaj, Iran. Sampling was carried out 12 times from 2 surface water streams (6 of each) in Karaj. Serial dilutions from each sample were prepared and samples were filtered. Filters were put on Hicrome aureus agar and incubated for 48 h at 37ºC. Black colonies were selected and identified at the species level using biochemical tests. Susceptibility of isolates to oxacillin was determined using disc diffusion and broth micro dilution assays. Resistance of MRSA isolates to 12 antibiotics was determined. SCCmec typing of MRSA isolates was done using multiplex-PCR. Totally, 288 S. aureus strains were isolated from different media. Prevalence of MRSA isolates was 12.8%. MRSA isolates showed high resistance to ciprofloxacin, erythromycin, tobramycin, amikacin, tetracycline, kanamycin and clindamycin, respectively. All MRSA isolates harbored SCCmec type III. In conclusion, our results illustrate the presence and persistence of highly resistant clonal group of MRSA in surface water in Karaj, Iran. High prevalence of SCCmec type III among MRSA isolates indicating an epidemiological link between the isolates from the sewage and human infections. Spread of these highly resistant MRSA isolates via surface water could be a serious warning for public health.