Molecular characterization of healthcare and community-associated methicillin-resistant using phage open-reading frame typing.

The polymerase chain reaction-based open reading frame typing (POT) method is a simple and rapid method for the strain-level discrimination of methicillin-resistant (MRSA). We investigated the molecular characteristics of strains by multilocus sequencing typing (MLST) and POT and the profiles of antibiotic resistance and virulence genes of MRSA isolates in a single center of Tokyo, Japan. Five types by MLST and 19 types by POT were detected in the 25 MRSA isolates. ST5 and a POT1 score of 93 were associated with healthcare-associated MRSA, whereas ST8 and a POT1 score of 106 were associated with community-associated MRSA. Each strain evaluated by POT score was completely associated with similar profiles of antibiotic resistance and virulence genes. These data showed that the POT system was a powerful molecular tool for the epidemiological characterization of MRSA isolates, which correlated with the profiles of antibiotic resistance and virulence genes.