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Article Type

Original Study

Abstract

Objective The aim of the study was to assess vancomycin-resistant Staphylococcus aureus (VRSA) in the National Liver Institute. Background VRSA refers to the strains of S. aureus that have become resistant to vancomycin. Three classes of VRSA have emerged: vancomycin intermediate-resistant S. aureus, heterogenous vancomycin-intermediate S. aureus, and high-level VRSA. Materials and methods The study was carried out on 705 samples that were collected from patients, personnel, and hospital environments. Group I (the patient group) included samples from 555 patients. From them different microbiological samples were collected (blood, urine, sputum, wound aspiration, nasal swab, throat swab, drains, and endotracheal tubes). Group II (the personnel group) included 45 samples from staff members who were in contact with the patients. Swabs were taken from their noses, throats, and fingertips. Group III (the hospital environment) included samples from 105 swabs. Samples from all groups were subjected to culture and isolation of the bacteria and identification of S. aureus isolates. These isolates were subjected to an antibiogram using the disc diffusion method, and testing for vancomycin susceptibility by the disc diffusion method, an E-test (E-test strip is Hi Media laboratories Pvt. Limited, Mumbai, India), and Vitek-2 compact (Vitek-2 is bioMιrieux, Inc., Durham, NC). VRSA isolates were subjected to analysis of plasmid DNA profile and restriction fragment length polymorphism (RFLP) PCR of isolated plasmids to detect the vanA gene. Results This study showed that, of 145 isolated S. aureus strains, 58.64% were vancomycin-sensitive S. aureus, 20.68% were vancomycin intermediate-resistant S. aureus, and 20.68% were VRSA. Their plasmid profile showed that 10% had no plasmid, 26.7% had one plasmid, 50% had two plasmids, and 13.3% had three plasmids. The molecular weight of most plasmids was 100 kb (36%). RFLP PCR for detection of the vanA gene in the isolated plasmids was positive in 51.9%. Conclusion VRSA prevalence in the National Liver Institute is 20.68%. The majority (90%) carried plasmids. Most plasmids had a molecular weight of 100 kb, and the vanA gene, as detected by RFLP PCR, was positive in 51.9%.

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