Molecular Detection of vanA and vanB Genes in Vancomycin-Resistant Enterococcus Isolated by Polymerase Chain Reaction From the Intestines of Children Admitted to the Intensive Care Units

Background: Enterococci are considered as the third most common cause of nosocomial infections and their antimicrobial resistance has been a concerning issue. Objectives: In this study, we looked for resistance genes of vanA and vanB in vancomycin-resistant Enterococcus (VRE) isolated from intestinal colonization of children admitted to the pediatric intensive care unit (PICU) and neonatal ICU (NICU) of Ali-Asghar Children's Hospital. Patients and Methods: In this descriptive study, 71 rectal swab samples were collected from the intestines of children admitted to the PICU and NICU of Ali-Asghar Children's Hospital. Enterococci were diagnosed in samples by appropriate microbiological tests. Antimicrobial resistance and VRE detection was performed by the Kirby-Bauer disk diffusion method on Mueller-Hinton agar based on Clinical and Laboratory Standards Institute ( CLSI) criteria. vanA and vanB genes were detected by PCR. Results: Enterococcus was detected in 64 (90.1%) rectal swab samples. The frequency rate of VRE strains was 47 (73.4%) and vancomycin-intermediate Enterococcus (`VIE) strains was 6 (9.4%). PCR analysis of VRE samples showed that 42 samples had vanA gene (89.3%) but vanB gene was not identified in remaining five samples. VIR was detected in 4 cases with vanA gene (66.7%). Again, we did not d vanB gene in remaining samples. Conclusions: VRE colonization was very high among studied cases. Most important mechanism for high level of resistance to vancomycin is presence of van genes, which can be potentially transmittable to other enterococci and gram-positive organisms. More molecular studies are needed to clarify the trend of VRE colonization and the role of preventive measures in this setting.