Prevalence of Vancomycin-Resistant Van A and Van B Genes in ESKAPE Gram-Positive Bacteria Isolated from Hospitalized Patients in Mashhad, Iran

Abstract

Introduction: The ESKAPE group, comprising Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecium, is known for its role in hospital-acquired infections and its growing resistance to antimicrobial agents. This resistance complicates treatment options, particularly with last-resort antibiotics, such as vancomycin. This study aims to determine the prevalence of vancomycin-resistant genes (Van A and Van B) in Staphylococcus aureus and Enterococcus species isolated by polymerase chain reaction (PCR) method from hospitalized patients in Mashhad, Iran. Materials and Methods: A total of 1000 clinical samples were collected over six months from hospitalized patients in four hospitals in Mashhad, Iran. The samples included blood, urine, wound swabs, and respiratory secretions. Staphylococcus aureus and Enterococcus isolates were identified through standard microbiological tests. Vancomycin susceptibility was assessed using the E-test method. The presence of vancomycin-resistant genes (Van A and Van B) was determined by PCR method. Results: Out of a total of 98 bacterial isolates, 77 were identified as Staphylococcus aureus and 21 as Enterococcus species. Among the Enterococcus isolates, 15 were identified as Enterococcus faecium and 6 as Enterococcus faecalis. Vancomycin resistance genes were detected in 7 isolates in total, with 6 of these isolates harboring the Van A gene and 1 carrying the Van B gene. Conclusion: The study reveals 40% and 1.3% prevalences of vancomycin resistance in Enterococcus faecium and Staphylococcus aureus isolates, respectively. These findings underscore the critical need for vigilant antibiotic stewardship and the implementation of appropriate treatment strategies to effectively manage infections caused by these resistant pathogens.