Characterization of Vancomycin Resistant Staphylococcus Aureus Isolated from Outpatients in Iraq

Abstract

Increasing the prevalence of vancomycin resistant Staphylococcus aureus (VRSA) among the community and in healthcare settings has become a global public health concern. This study aimed to investigate the prevalence and antimicrobial susceptibilities of VRSA among outpatients. Seventy-nine isolates of methicillin-resistant S. aureus were collected from 380 various clinical specimens. Antimicrobial susceptibilities were investigated by disk diffusion method and vancomycin MIC was determined by agar dilution method. Molecular characterization of tested isolates was performed by PCR technique to detect the mecA and vanA/vanB genes. The results showed the highest resistance to cefoxitin (79 isolates, 100%), augmentin (73 isolates, 92.4%) and moderate resistance to erythromycin (42 isolates, 53.2%), tetracycline (40 isolates, 50.6%) and clindamycin (30 isolates, 38%). While high susceptibility was found to imipenem, gentamicin and vancomycin which had 78.67%, 82.66% and 91%, respectively. Two strains were resistant to vancomycin (MIC 32 mg/L), and six strains were intermediate to vancomycin (MIC 2 – 4 mg/L). All tested isolates were found positive for mecA but none of them have demonstrated vanA/vanB gene by PCR. The study concluded that the emergence of vancomycin resistance in MRSA from outpatients portends the health authorities to detect and identify these organisms and to find an alternative treatment.