Abstract
IntroductionThe emergence of methicillin-resistant Staphylococcus aureus (MRSA) in different patient populations is a major public health concern. This study determined the prevalence and distribution of circulating molecular types of MRSA in hospitalized patients in ICU of hospitals in Tehran.Materials and MethodsA total of 70 MRSA isolates were collected from patients in eight hospitals. Antimicrobial resistance patterns were determined using the disk diffusion method. The presence of toxin encoding genes and the vancomycin resistance gene were determined by PCR. The MRSA isolates were further analyzed using multi-locus sequence, spa, SCCmec, and agr typing.ResultsThe MRSA prevalence was 93.3%. Antimicrobial susceptibility testing revealed a high resistance rate (97.1%) to ampicillin and penicillin. The rate of resistance to the majority of antibiotics tested was 30% to 71.4%. Two isolates belonging to the ST22-SCCmec IV/t790 clone (MIC ≥ 8 μg/ml) had intermediate resistance to vancomycin. The majority of MRSA isolates (24.3%) were associated with the ST22-SCCmec IV/t790 clone; the other MRSA clones were ST859-SCCmec IV/t969 (18.6%), ST239-SCCmec III/t037 (17.1%), and ST291-SCCmec IV/t030 (8.6%).ConclusionsThe circulating MRSA strains in Iranian hospitals were genetically diverse with a relatively high prevalence of the ST22-SCCmec IV/t790 clone. These findings support the need for future surveillance studies on MRSA to better elucidate the distribution of existing MRSA clones and detect emergence of new MRSA clones.
Highlights
The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in different patient populations is a major public health concern
Two isolates belonging to the ST22-staphylococcal cassette chromosome mecA (SCCmec) IV/t790 clone (MIC 8 μg/ml) had intermediate resistance to vancomycin
The circulating MRSA strains in Iranian hospitals were genetically diverse with a relatively high prevalence of the ST22-SCCmec IV/t790 clone
Summary
A total of 70 MRSA isolates were collected from patients in eight hospitals. Antimicrobial resistance patterns were determined using the disk diffusion method. The MRSA isolates were further analyzed using multi-locus sequence, spa, SCCmec, and agr typing. This cross-sectional study was conducted from November 2014 to July 2015 in eight hospitals: two in northern Tehran (A1 and A2), two in central Tehran (B1 and B2), two in southern Tehran (C1 and C2), one in eastern Tehran (D1), and one in western Tehran (D2). A case of healthcare-associated MRSA was considered as being hospital onset (HO) if a positive culture of MRSA was obtained on or after 96 hours of admission to a hospital It was considered as community onset (CO) if the culture was obtained before the fourth calendar day of hospitalization and had one of more of the following features: (1) a history of hospitalization, surgery, dialysis, or residence in a long-term care facility within 12 months preceding the culture date, or (2) the presence of a central vascular catheter (CVC) within the 2 days prior to MRSA culture
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