title: Comparison of an automated repetitive-sequence-based PCR microbial typing system with pulsed-field gel electrophoresis for molecular typing of vancomycin-resistant Enterococcus faecium.
abstract: Vancomycin-resistant Enterococcus faecium (VRE) has become an important health care-associated pathogen because of its rapid spread, limited therapeutic options, and possible transfer of vancomycin resistance to more-virulent pathogens. In this study, we compared the ability to detect clonal relationships among VRE isolates by an automated repetitive-sequence-based PCR (Rep-PCR) system (DiversiLab system) to pulsed-field gel electrophoresis (PFGE), the reference method for molecular typing of VRE. Two sets of VRE isolates evaluated in this study were collected by active microbial surveillance at a large teaching hospital in Taiwan during 2008. The first set included 90 isolates randomly selected from the surveillance cohort. The first set consisted of 34 pulsotypes and 10 Rep-PCR types. There was good correlation between the two methods (P < 0.001). The second set included 68 VRE isolates collected from eight clusters of colonization. A dominant clone was detected in five out of eight clusters by both methods. Two clusters were characterized by Rep-PCR as being caused by a dominant clone, whereas PFGE showed polyclonal origins. One cluster was shown to be polyclonal by both methods. A single Rep-PCR clone type was detected among 12 of 14 vancomycin-intermediate enterococci, whereas PFGE detected six pulsotypes. In conclusion, the Rep-PCR method correlated well with PFGE typing but was less discriminative than PFGE in defining clonal relationships. The ease of use and more rapid turnaround time of Rep-PCR compared to PFGE offers a rapid screening method to detect outbreaks of VRE and more rapidly implement control measures. PFGE remains the preferred method to confirm clonal spread.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Taipei, Taiwan.
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chuang
authors.forename: Jann-Tay
authors.initials: JT
authors.lastname: Wang
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Chen
authors.forename: Yee-Chun
authors.initials: YC
authors.lastname: Chen
mesh_terms: D001331:Automation / Q000379:methods; D015373:Bacterial Typing Techniques / Q000379:methods*; D016000:Cluster Analysis; D016172:DNA Fingerprinting / Q000379:methods*; D016521:Electrophoresis, Gel, Pulsed-Field; D016984:Enterococcus faecium / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006784:Hospitals, Teaching; D006801:Humans; D020071:Interspersed Repetitive Sequences; D017720:Molecular Epidemiology / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods*; D013624:Taiwan; D020713:Vancomycin Resistance