Comparison of repetitive extragenic palindromic sequence-based PCR with PCR ribotyping and pulsed-field gel electrophoresis in studying the clonality of Clostridium difficile.

Clostridium difficile infection is most often induced by antibiotic treatment. Recently, morbidity and mortality resulting especially from C. difficile PCR ribotype 027 have increased significantly. In addition, more severe disease has been associated with C. difficile PCR ribotype 078 strains. Thus, reliable typing methods for epidemic control are needed. In the present study, we compared an automated repetitive extragenic palindromic sequence-based PCR (rep-PCR) method (DiversiLab; Bacterial Barcodes, Inc., Athens, GA, USA) to PCR ribotyping and pulsed-field gel electrophoresis (PFGE) typing using 205 isolates of C. difficile (including 24 previously characterized isolates). Among the 181 clinical isolates, a total of 31 different PCR ribotypes, 38 different PFGE types and subtypes and 28 different rep-PCR types were found. Six major rep-PCR groups (DL1-DL6) harboured 86% of the clinical isolates. All isolates belonging to PCR ribotypes 027 and 001 clustered in their own rep-PCR groups, enabling us to screen out the hypervirulent ribotype 027 strain. Within the PCR ribotype 001, four subgroups were found using rep-PCR. Overall, in 75% (135/181) of the isolates, the classification attributed following rep-PCR and PCR ribotyping was comparable. In conclusion, the automated rep-PCR-based typing method represents an option for first-line molecular typing in local clinical microbiology laboratories. The method was easy to use as well as rapid, requiring less hands-on time than PCR ribotyping or PFGE typing. The conventional PCR ribotyping or PFGE, however, are needed for confirmatory molecular epidemiology. In addition, more epidemiology-oriented studies are needed to examine the discriminatory power of automated rep-PCR with isolates collected from a larger geographical area and during a longer period of time.

Emergence of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae during the years 2000 and 2004 in Helsinki, Finland.

The molecular epidemiology of 33 Escherichia coli and 81 Klebsiella pneumoniae extended-spectrum beta-lactamase-producing healthcare-associated and community-acquired isolates collected in the Helsinki district during 2000-2004 was investigated. Clonality studies, antimicrobial susceptibility and genotyping of the isolates were performed. Newly emerging CTX-M-producing E. coli and bla(SHV-12)-producing K. pneumoniae isolates were detected. Clonal clusters of both species persisted throughout the study period.