Prophage Typing of Meticillin Resistant Staphylococcus aureus Strains Isolated from Sewage Treatment Plants in Tehran

Staphylococcus aureus is a common cause of infection among human which contain broad spectrum of lysogenic phages and various virulence factors. Bacteriophages are involved in production of virulence factors via positive and negative lysogenic phage conversion. The aim of this study was to analyze different prophage types of methicillin resistant Staphylococcus aureus strains isolated from a sewage treatment plant (STP) in Tehran during 2010. Totally 653 isolates of S. aureus was collected from a STP in Tehran. All isolates were identified at the species level using specific primers. Susceptibility of isolates selected to oxacillin was determined using disc diffusion and Etest. Presence of mecA gene was checked by PCR. Primers for identification of 6 classes of prophages were used in a Multiplex-PCR assay. All S. aureus strains were confirmed using specific species primers. Amongst all isolates, 100 strains showed resistance to oxacillin. Resistance in 51% and 6% of MRSA isolates was very high and very low (MIC≥256 μg/ml) and (MIC≥4 μg/ml), respectively. One hundred percent of the MRSA isolates contained mecA gene. Five different prophage types and also 4 different prophage patterns were identified among MRSA isolates. All isolates contained at least 1 prophage types and 2 subtypes. The results indicating presence and persistence of clonal MRSA isolates in a sewage treatment plant in Tehran. Moreover, high prevalence of different classes of prophages among MRSA isolates indicating the potential of these strains to produce various virulence factors.