To establish a quick and reliable method for detecting the mec A gene through the MRSA(methicillin resistant Staphylococcus aureus) dot blot hybridization technique using PCR (ploymerase chain reaction)-amplified probe DNA, 81 strains of MRSA
were
collected from 3 different hospitals and tested through the disk diffusion methods between January 1992 and Decembber 1993. Of the 3 hospitals, two were affiliated with universities and located in Seoul, and the third was a general hospital
situated in
a rural setting some hundred miles from Seoul. Only 68 of the 81 strains (84.0%)were found to be MRSA by the standard agar diffusion test as described in the NCCLS manual (USA) using Muller-Hinton agar supplemented by NaCl. These results were
found
to
be identical to those following the PCR method. Of the 13 strains in which MRSA was not detected by the standard agar diffusion test, only one strain(MIC, 8μg/ml of methicillin) was found to contain the mec A gene when tested by PCR and dot blot
hybridization. PCR and dot blot hybridization were found to be the best methods for detecting MRSA given to the goals of rapidity, accuracy, and cost effectiveness Amikacin- resistant MRSA was noted with abnormally high frequency in the samples
from one
of the university hospitals. Plasmid profiles of MRSA provided critical evidence of endemic nosocomial strains, allowing for the differentiation of the clones origins and some assessments regarding the MRSA's molecular epidemiology. Similarities
in
the
molecular size of plasmids obtained from the uban and rural hospitals suggested the spread of MRSA among the hospitals throgh the movement of healthcare personnel and patients. Finally the MRSA strains from the two university hospitals within
Seoul
showed distinct plasmid profiles. In general, the prevalence of eiprofloxacin-resistant MRSA was highly correlated with the absence of plasmid.
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