Subtyping of methicillin-resistant Staphylococcus aureus isolates from theNorth-West of England: a comparison of standardised pulsed-field gel electrophoresis with bacteriophage typing including an inter-laboratory reproducibility study

Bacteriophage typing is currently the recognised methodology for the typing of methicillin-resistant Staphylococcus aureus (MRSA) in the UK, Bacteriop hage typing is less discriminatory and does clot type all isolates compared with some molecular methods for typing MRSA. Chromosomal genotyping by pul sed-field gel electrophoresis (PFGE) is increasingly recognised as an impro ved method for typing MRSA, providing increased discrimination and typabili ty. In this study the results of a comparison of bacteriophage typing and P FGE typing and subtyping are presented for a large collection of isolates f rom the North-West of England, Isolates belonging to the most frequently is olated epidemic methicillin-resistant Staphylococcus aureus (EMRSA) bacteri ophage types 15 and 16 were typed by PFGE with further discrimination of co mmon PFGE types possible into a number of subtypes, These results for a lar ge collection of isolates demonstrate the improved typing of MRSA with PFGE , The widespread acceptance of PFGE for typing MRSA isolates has been hampe red by the lack of standardised methodologies, Recently, a standardised PFG E strain typing system, known as the GenePath system has become available. The results of an inter-laboratory comparison of PFGE typing for a collecti on of isolates demonstrated good reproducibility with this system.