Study on Vancomycin-resistant Enterococci Carried by Intestinal Tract in Different People Groups

Abstract:

To investigate the rate of carriage, the phenotype, the genotype and homology in stool specimen from outpatients, inpatients and health adult for prevention and guiding the clinical treatment. According to CLSI’s guideline, antimicrobial susceptibility tests were performed; To detect vancomycin resistant gene by PCR; To analyze the homology by REP-PCR method. The vancomycin resistant carriage rate in intestinal tract of inpatients was 20.67%. All 22 isolates harbored VanA genotype; 9 isolates harbored VanC1 genotype. The homology in 22 vancomycin resistant enterococci was mostly type A, which was divided into A1-A5 subtypes, and they had high homology. Type A had 19 isolates. Of all, type A1 had 4 isolates; type A2 had 6 isolates; type A3 had 4 isolates; type A4 had 3 isolates; type A5 had 2 isolates. Type B、C、D had no subtypes. Three pairs of isolates had 100% homologies. There were 4 isolates (4%) separated from outpatients. All were vanC1 types. Two were likely to be the same isolate. There were 11 isolates (27.5%) separated from health adults. Of all, 8 isolates were VanC1, and the others were vanC2. The homology in 11 VIE was mostly type A, which was divided into A1-A4 subtypes. Type A1 had 1 isolate; type A2 had 2 isolates; type A3 had 1 isolate; type A4 had 1 isolate. Type D1、D2、D3 was 1 isolate separately. Type B、C、E had no subtypes. Two VIE from inpatients and two from outpatients had 100% homologies. The other two VIE from inpatients and two from outpatients had 100 homologies, too. They had low homology with the isolates from health adults.Minimum inhibitory concentration (MIC) of 22 VRE to vancomycin were > 512μg/mL; MIC of 16 VIE to vancomycin were 16μg/mL; MIC of 8 VIE to vancomycin were 8μg/mL. It is a risk factor for hospital infection that VRE carriage of inpatients in intestinal tract is high. There is 100% agreement between phenotypes and genotypes in 46 vancomycin resistance enterococci. VRE are multiresistant. Part isolates have high homology.