High Diversity of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates Based on Hypervariable Region Polymorphisms

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is considered one of the most important pathogenic bacteria and most prevalent pathogens causing dangerous infections in humans. Objectives: The purpose of this study was to analyze the hypervariable region (HVR) diversity of clinical MRSA isolates in Tabriz, northwestern Iran. Methods: In this retrospective and descriptive study, from Staphylococcus aureus strains isolated from clinical specimens of hospitalized patients from 2006 to 2013 at Tabriz health centers, 151 isolates were randomly selected. Methicillin-resistant isolates were identified by the agar disk diffusion method and mecA PCR assays. The genetic diversity of the isolates in the HVR were analyzed with the HVR typing method. Results: According to the antibiogram test results, from 151 samples, 52 isolates (34.4%) were resistant to cefoxitin. However, based on the polymerase chain reaction (PCR) assay, 54 isolates (35.8%) had the mecA gene and were identified as MRSA strains. According to PCR of the mecHVR, these MRSA strains were classified into seven different genotypes of HVR groups. Conclusions: High HVR diversity among the studied MRSA isolates could be a result of insufficient or inadequate infection-control protocols in Tabriz hospitals. Moreover, the high number of HVR genotypes showed that HVR typing can be used along with other typing methods in epidemiological studies of MRSA as a useful tool for monitoring, tracking contaminations, and controlling infections in hospital settings.