SIMULTANEOUS PERSISTENCE OF METHICILLIN-RESISTANT AND METHICILLIN-SUSCEPTIBLE CLONES OF STAPHYLOCOCCUS-AUREUS IN A NEONATAL WARD OF A WARSAW HOSPITAL

Fifty-seven methicillin-resistant Staphylococcus aureus (MRSA) isolate s from babies (N=31), carriers amongst health care workers (N=16; 10% of all staff members) and the environment (N=10); 39 MSSA isolates, fr om babies (N=18), health care workers (N=5) and environment (N=16) wer e analysed. The strains were from the neonatal ward of a teaching hosp ital in Warsaw and were collected over a period of 16 months (1993/199 4). The isolates were characterized by phage-typing, arbitrary-primed polymerase chain reaction (AP PCR), DNA repeat polymorphism within the protein A gene and the resistance pattern to antimicrobial agents. Th e presence of the mecA gene was determined by PCR. MRSA were classifie d as heterogeneously resistant to methicillin, susceptible to other an timicrobial agents and, except for three isolates, appeared to be geno typically almost identical. The first example of mupirocin resistant M RSA in Poland was documented. Amongst MSSA isolates, increased variabi lity was seen, however, the persistence of one predominate clone of MS SA was shown. In this particular hospital environment, several differe nt strains of both MRSA and MSSA were capable of maintaining persisten t colonization.