IDENTIFICATION OF METHICILLIN-RESISTANT STAPHYLOCOCCI BY MULTIPLEX POLYMERASE CHAIN-REACTION ASSAY

A multiplex polymerase chain reaction (PCR) assay using oligonucleotid e primers to detect mecA and 16S ribosomal RNA gene was developed to a id in identification of methicillin-resistant staphylococci. Validatio n included 99 isolates of staphylococcus grouped into one of five cate gories: methicillin-susceptible coagulase-negative staphylococcus (MSC NS), methicillin-resistant coagulase-negative staphylococcus (MRCNS), methicillin-susceptible Staphylococcus aureus (MSSA), high beta-lactam ase producing S aureus (HiBSA), and methicillin-resistant S aureus (MR SA). mecA was detected in MRSA (21/21), and in MRCNS (20/20), but not in MSSA (0/20). mecA was occasionally detected in MESA (1/19) and MSCN S (3/19). This multiplex PCR assay was also used to test 30 clinical i solates of coagulase-negative staphylococci with discrepancies between results of in vitro tests for susceptibility to oxacillin and was fou nd to be valuable when a more definitive determination of intrinsic me thicillin-resistance was desired.