Epidemiological typing of serratia marcescens.

Abstract

Serratia marcescens is a common cause of hospital acquired infections. Epidemiological studies are often performed on this and other potential pathogens to identify and possibly prevent future outbreaks. Of the many epidemiological techniques available, polymerase chain reaction (PCR) based typing techniques are commonly employed. Examples include randomly amplified polymorphic DNA (RAPD), repetitive extragenic palindromic (REP) elements, enterobacterial repetitive intergenic consensus (ERIC) sequences, polymorphic GC-rich repetitive sequence (PGRS), and ribotyping. In this study, RAPD, REP, ERIC, PGRS, and ribotyping were used to compare the genetic relationship among 62 clinical S. marcescens isolates. After amplification, reaction products were analyzed by agarose gel electrophoresis and banding patterns among each isolate were compared using dendrograms. RAPD analysis using primer 1254 yielded 41 genotypic groups, primer 1283 resulted in 43 genotypic groups, primer 1060 amplified 37 genotypic groups, and the combination of primers 1254 and 1283 yielded 43 genotypic groups. REP amplified 54 genotypic groups, ERIC resulted in 19 genotypic groups, PGRS produced 60 genotypic groups, and ribotyping yielded 40 genotypic groups. Antimicrobial susceptibility patterns using antibiotic gradient plates were also used to differentiate these isolates. Data obtained were used to generate 37 phenotypic groupings based on dendrogram analysis. Of the techniques evaluated, PGRS provided the most discriminatory power to identify genomic differences among the 62 S. marcescens isolates.