Emergence of high-level vancomycin-resistant Staphylococcus aureus in the Imam Khomeini Hospital in Tehran

Abstract

Objective: The objective of the study was to investigate the prevalence of vancomycin-resistant Staphylococcus aureus (VRSA).

Materials and methods: Three hundred and fifty-six S. aureus isolates from the Imam Khomeini hospital in Tehran, Iran, were evaluated for methicillin and decreased vancomycin susceptibility by the microbroth dilution method. The mecA, vanAand vanB genes were targeted by polymerase chain reaction.

Results: Of the 356 isolates, 149 (41.85%) S. aureus strains were resistant to methicillin. Two strains of methicillin-resistant S. aureus were VRSA strains. One isolate, Teaching Hospital-1 (TEH-1), had a vancomycin minimum inhibitory concentration (MIC) of 64 microg/ml and was susceptible to teicoplanin while the other isolate (TEH-2) had a vancomycin and teicoplanin MIC of 512 and >256 microg/ml, respectively, and was positive for the vanA gene.

Conclusion: This report shows that the emergence of VRSA in Iran warrants active microbiological surveillance and careful monitoring of vancomycin therapy.