Comparison between phage-open-reading frame typing and automated repetitive-sequence-based PCR for typing MRSA isolates.

Abstract

The methods for typing and epidemiological study for especially antibiotic-resistant bacteria has been issued but there are the debates regarding which method is best for this purpose. The purpose of this study is to investigate and apply a comparatively new technology, phage-open-reading frame typing (POT) and repetitive-sequence-based PCR (rep-PCR) using DiversiLab system and compare for the discrimination of major methicillin-resistant Staphylococcus aureus (MRSA) lineages in epidemiological surveillance. We analyzed 47 representative MRSA stains isolated in Kobe University Hospital between January and December 2009. We performed MRSA typing using the POT kit and rep-PCR using the DiversiLab system. POT method classified all the MRSA strains into 35 clusters, whereas rep-PCR method typed all the MRSA strains in 10 kinds of clusters with a definition of 95% similarity. The discriminatory power and congruence between the methods were compared using the Simpson's index of diversity, adjusted Rand's and Wallace's coefficients. Our statistical analyses showed that the POT (POT 1-2-3 and POT 2-3) revealed a higher discriminatory power in the Simpson's index of diversity (SID; 0.969, range 0.939-1.000 and 0.967, range 0.935-0.998, respectively) for MRSA isolates than the rep-PCR (0.821 (0.767-0.876)). The adjusted Rand's and Wallace's coefficients did not show higher concordance among the methods. In conclusion, we demonstrated that the POT can perform accurate and reliable epidemiological surveillance studies for analyzing the genetic relatedness of MRSA strains.