[Antibiotics susceptibilities and other biological properties of methicillin-resistant Staphylococcus aureus: observation in the last 2 years in our university hospital].

ABSTRACT

We examined biological properties of strains of methicillin-resistant Staphylococcus aureus (MRSA) which were isolated in our ward in 1991 and 1992. A total of 47 MRSA strains were isolated in 1991 and 64 in 1992. The majority of these strains of MRSA were highly resistant to DMPPC, CEZ and IPM, and were intermediately resistant to MINO. All these strains were, however, sensitive to VCM. The number of coagulase type II strains increased from 22 (46.8%) to 51 (79.7%), and that of enterotoxin type A strains from 27 (57.4%) in 1991 to 47 (73.4%) in 1992. The number of strains which produce Toxic Shock Syndrome Toxin-1 (TSST-1) also increased from 19 (40.4%) to 45 (70.3%), and those strains that produce beta-lactamase decreased from 24 (51.1%) to 21 (32.8%). From the above results, we confirmed the recent change in types of the epidemic strains of MRSA. Namely, there was a marked increase in number of strains which produce type II coagulase type A enterotoxin and TSST-1. For the prevention of a patient to patient-, room to room- and ward to ward-spread, strict isolation was indicated both the infection patients, immunocompromised patients who were at high risk for the infection and the proved carriers. Treatment with VCM was started immediately if MRSA infection was thought plausible. These countermeasures seemed to succeed in reducing the incidence of the infection in our ward.