الفهرس 
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Abstract
VRE has become an important nosocomial pathogen because of its rapid spread, limited options for treatment and possibility of transferring vancomycin resistance genes to other more virulent and more prevalent pathogens such as S. aureus. Not all laboratories have molecular biology techniques in their routine clinical practice. For this reason, it is essential that phenotypic techniques able to detect VRE isolates in a rapid and accurate manner be available, in order to ensure correct antibiotic treatment and to avoid the spread of VRE isolates in the hospital environment. The aim of the study is to detect the prevalence of nosocomial enterococcal infections, and the prevalence of Vancomycin resistance among Enterococci by different phenotypic methods, in order to ensure correct antibiotic treatment.
This study included 117 Enterococcal isolates from various clinical samples1392 collected from patient with suspected nosocomial infections in different department of MUHs. Enterococcal isolates were identified by colonial morphology, gram stain, catalase reaction and bile esculin hydrolysis. Vancomycin resistance was identified by disc diffusion, chrom ID VRE agar &E-test as a reference method. Species identification of the resistant isolates was done by API 20 STREP. The 117 enterococcal isolates represented 8.4 % of all nosocomial pathogens. The nosocomial enterococcal infections represented 17.0% of urinary tract infections, 8.1% of blood stream infections, 7.6% of wound sepsis and 7.4% of lower respiratory tract infections. vancomycin resistance was detected using MIC method by(E-test) which was considered as a reference method in our study .It detected 22 isolates (18.8%) resistant to vancomycin out of the 117 Enterococcal isolates. The disk diffusion method for vancomycin was used as routine susceptibility testing method because of its low cost and easily technical performance. The disk diffusion method is not enough reliable method for detecting vancomycin susceptibility testing as it detected only 17 VRE isolates (14.5%). Its accuracy was 77.3 vs E-test. The 22 VRE isolates were cultured on chromID VRE agar. chromID VRE agar reduced the need for additional biochemical analysis or antimicrobial susceptibility testing in the clinical laboratory. It detected only 20 VRE, so its accuracy was 90.9% compared with E-test. It detected 19 E.faecium forming purple colonies and one E.faecalis forming blue-green colonies. E.faecium and E.faecalis are the Enterococcal species most frequently isolated from the 22 VRE isolates, 19 E.Faecium representing (86.4%) while the 3 E.Faecalis representing (13.6%) by API-20 test. By E-test 2 E.faecium isolates and 2 E.Faecalis were intermediately resistant to vancomycin , one isolate of E.Faecalis was highly resistant,while 17 of E.faecium isolates demonstrated great resistant to vancomycin (77.3%). The antimicrobial susceptibility results of the VRE isolates, showed that imipenem and cefipime produced marked inhibitory effect on VRE while all other antimicrobials were of limited effect. In our study the VRE were resistant to ciprofloxacin (95.7%) ampicillin (90.5%) tetracycline (76.9%) and erythromycin (63.9%) while 41.1% of the isolates were resistant to cephotaxime which can lead to difficulty in treatment of such infections. As most of the VRE isolates in our study were E. faecium, it can be responsible for this resistance to antibiotics. VRE isolation was significantly high in patients with age ranged from 28-60 years old, with no relationship with patients gender. It is highly isolated from ICU unites (45.5%) followed by surgical wards (31.8%). Among the several factors analyzed, we found that the most important factors that were associated with VRE infections : prolonged hospitalization, prolonged intake of third generation cephalosporins and vancomycin.