Molecular subtyping of vancomycin resistant enterococcus: A comparison of two molecular methods

Introduction: Arbitrarily Primed-Polymerase Chain Reaction (AP-PCR) and Pulsed-Field Gel Electrophoresis (PFGE) are widely used genotyping methods for investigating outbreaks of infections. The aim of this research is to compare AP-PCR with PFGE, which is known as the gold standard method, and to determine if AP-PCR is suitable for use in outbreaks.Materials and methods: Between 2001 and 2009, 664 isolated vancomycin resistant enterococcus (VRE) strains were determined at the Bacteriology Laboratory, Department of Medical Microbiology. During nine years study 5 peak periods were identified. In each peak period of 3 months, 83 VRE strains were selected from the 664 for this research. For all isolates a comparison of AP-PCR and PFGE using 83 VRE strains was performed.Results: Enterococcus faecium was found to be the dominant species in all VRE isolated from hospitalized patients. 83 strains of E. faecium were included in the study, which were isolated from 5 different possible epidemic periods over 9 years. 15 different clonal strains were collected using the AP-PCR method and 11 using PFGE.Conclusion: PFGE was found to be repeatable and had a better separation power than AP-PCR. AP-PCR though is a simpler,cheaper and faster method and can be used for VRE epidemics as an alternative method. In future epidemiological outbreaks the comparative molecular methods are more reliable than a single method.