Characteristics of hospital- and community-acquired meticillin-resistant Staphylococcus aureus in Tehran, Iran

Staphylococcus aureus is a leading cause of hospital-acquired (HA) and community-acquired (CA) infections worldwide. Recently, S. aureus strains resistant to meticillin (MRSA) have become established within both communities. We isolated 314 isolates of MRSA from hospitalized patients in a referral hospital (HA isolates) and 268 isolates from its outpatient clinic (CA isolates) in Tehran, Iran, between February 2008 and December 2010. These isolates were tested for their susceptibility to 17 antibiotics and typed using the PhPlate system. The diversity in the structures of staphylococcal cassette chromosome mec (SCCmec) elements and ccr types was also detected using a multiplex-PCR assay and isolates were examined for the presence of different classes of prophages. Whilst all isolates were resistant to penicillin, the HA isolates were significantly more resistant to all other antibiotics tested than the CA isolates. Isolates carrying only SCCmec type III and ccr type 3 were dominant (91 %), but 20 % of the CA isolates belonging to less prevalent types carried only SCCmec types IVa, c and ccr type 2. These isolates also carried pvl genes and contained SGA prophage type. Our results indicate that whilst the dominant clonal groups of HA- and CA-MRSA belong to SCCmec type III and carry ccr type 3 genes, several distinct but less prevalent types of CA-MRSA carrying SCCmec type IVa, c and type 2 ccr are also found in Tehran. These strains carry pvl genes and the SGA prophage type, a characteristic that might be used as a marker for detection of CA-MRSA in this country.