FREQUENCY AND ANTIMICROBIAL SUSCEPTIBILITY OF OXACILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS IN A TEACHING HOSPITAL

From October 1993 till October 1994, 115 oxacillin resistant Staphyloc occus aureus strains were isolated in the laboratory of a teaching hos pital. This was 2.4 % of all of the Staphylococcus aureus strains. The bacteria were isolated from 30 patients, 7 medical personnel and in t he environment of the infected patients. Most of the isolates were cul tured from blood cultures, wound swabs and drains. If the referring ho spitals has been informed about the MRSA status of the patients, sever al transmissions could have been prevented. In 10 infected patients, t he MRSA strains were isolated from the nose, throat and hands. The iso lates were also found on the hands of several personnel and in the pat ients environment, suggesting that the strains had been widely spread. The MRSA strains predominated in the medical and surgical intensive c are units and in 2 general surgical wards. They were only found sporad ically in other departments (Ophthalmology, Gynaecology, Paediatrics a nd Urology). MRSA-strains were more resistant to imipenem, ofloxacin? gentamicin, trimethoprim-sulfamethoxazole, tetracycline, erythromycin and clindamycin as oxacillin-sensitive Straphylococcus aureus strains. Genotyping (Restriction-Fragmenc-Length-Polymorphism) revealed six di fferent strain patterns. The same RFLP types were mainly found on diff erent wards. We conclude that various clones of MRSA may have emerged independently within one hospital and that their spread between wards was remarkably limited. Subsequent intensive hygiene measures have bee n succesful in reducing the number of new isolates.