DETECTION OF METHICILLIN RESISTANT CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS: STANDARD SUSCEPTIBILITY TESTS VERSUS PCR AMPLIFICATION OF mec A GENE AND fem A GENE

Abstract

Spreading of methicillin resistant S. aureus (MRSA) is considered a grave problem in hospitals. Controlling of MRSA seems to be difficult and requires great efforts to eradicate it as eradication programs are very expensive even in developed countries.

The resistance of MRSA is not only to penicillins but also to• many antibiotics; erythromycin, aminoglycosides, clindamycin, chloramphenicol, tetracycline, trimethoprim­ sulfamethoxazole and quinolone making it difficult to control.

The disc diffussion method has been used for detection of MRSA as it is easy to use in routine laboratory work. However many investigators prefer it over agar dilution method which is time consuming, expensive and difficult to use routinely.

. It has been found that methicillin resistance of S. aureus is caused by production of special protein called penicillin binding protein 2a_. (PBP2a) which has low affinity to penicillin, and its productio1;1 is lioded by mecA gene. Another gene called femA gene seems to be essential for the expression of mecA gene. It has been documented that mecA is present in resistant strains and absent in susceptible ones.