بررسی فراوانی مقاومت به ونکومایسین در میان سویه‌های انتروکوکوس فسیوم جدا شده از عفونت‌های ادراری در بیمارستان‌های تهران

Background and Objective: Vancomycin-resistant enterococci (VRE) are the major causative agents of urinary tract infections (UTIs) in hospitalized patients. The aim of this study was to determine the prevalence of urinary tract infections caused by enterococcus faecium and the level of resistance to vancomycine and other antibiotics which are effective in enterococcal infection therapy of hospitalized patients in four university teaching hospitals of Tehran. Materials and Methods: This study was carried out between September 2011 and May 2012. Urine samples were collected from hospitalized patients in Taleghani, Loghman , Mofid and Labaffi nejad Hospitals in Tehran. Enterococcus species were detected by biochemical and molecular tests. Antimicrobial susceptibility and minimum inhibitory concentration (MIC) of vancomycine were determined by disk diffusion and micro agar dilution methods. The presence of vanA and vanB genes were investigated in VRE strains by PCR. Results: 86 enterococci were isolated from urine samples of which 45(52%) were E.faecium. 42.2% of E. faecium isolates were resistant to vancomycin (VRE) and showed vanA genotype. All VRE isolates were resistant to ampicillin, gentamicin, ciprofloxacin and erythromycin, and 78% were resistant to nitrofurantoin. Furthermore, all VRE isolates were sensitive to linezolide and quiopristin-dalfopristin. MIC50 ≥ 128 and MIC90 ≥ 256 were detected in the VRE strains. Conclusion: The increase in the prevalence of vancomycin resistant E. faecium with high risk resistance profiles is a serious threat for some Iranian hospitals and limits the therapeutical options for patients infected with E. faecium.