Division 2.3.2 Identification of MRSA

Presumptive S. aureus shall be identified as S. aureus and MRSA by PCR. The identification shall be performed using a multiplex PCR with simultaneous identification of the mecA-gene or two different PCR shall be performed. To limit the amount of work only one of the five presumptive S. aureus isolates shall initially be identified. If this isolate is identified as MRSA, it shall be stored. No further testing of the remaining four isolates is required if the first isolate is identified as MRSA and they can be discarded. If the first isolate is not identified as MRSA, the next of the initial five isolates shall be tested. This process shall continue until one MRSA has been identified or all five isolates have been tested. Alternatively, identification by PCR as a first step can be done on a pool of the five presumptive colonies from a sample. In case of a positive PCR, the analysis shall be repeated on individual colonies to identify a positive colony.

For quality assurance, 16 presumptive S. aureus isolates which were not identified as MRSA, as well as 16 MRSA strains, sampled over the whole year 2008 shall be sent to the CRL-AR. A proportion of these isolates shall be sent to the CRL-AR on a quarterly basis. In case less than 16 isolates were verified as MRSA all these isolates shall be sent.