PCR typing of Enterococcus faecium. An evaluation.

Abstract

In the last two decades enterococci, especially E. faecium, have emerged as a major cause of nosocomial infection. A knowledge of their epidemiology within the hospital environment is crucial for the implementation of effective infection control measures. Hence, in recent years much effort has been invested in evaluating various typing methods for use in these studies. These include serotyping, phage typing, enterococcine typing, biotyping, analysis of whole or digested plasmid DNA, digestion of amplified fragments of glycopeptide resistance genes, restriction endonuclease analysis of chromosomal DNA, ribotyping, IS6770 probing and various pulsed-field gel electrophoresis techniques (PFGE). Of these methods PFGE is becoming the method of choice and is regarded by some as the gold standard against which other methods should be assessed. However, the down side of PFGE is the expensive equipment required and the length of time (usually about five days) before results are available. For these reasons attention has turned to PCR typing methods, where equipment is relatively cheaper, the method is simple to perform and results are obtained within two days. Two PCR based methods have been applied to type E. faecium with varying success. PCR-ribotyping, although initially promising (4), is now not considered a useful option (1, 5). More recently Issack (3) applied one out of 26 short (10bp) primers screened to study the epidemiology of an outbreak of VRE at a teaching hospital. The method appeared useful and reasonably good reproducibility was achieved. However, no comparison with other typing methods was undertaken as in this study, where we have evaluated longer primers (15–23bp) and compared our results with those obtained by ribotyping and PFGE.KeywordsBanding PatternPhage TypingPFGE TypeBand DifferenceSmall Colony VariantThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.