ANALYSIS OF PRISTINAMYCIN-RESISTANT STAPHYLOCOCCUS-EPIDERMIDIS ISOLATES RESPONSIBLE FOR AN OUTBREAK IN A PARISIAN HOSPITAL

In 1990, over a 6-month period, an increase from 1 to 10% in the incid ence of pristinamycin resistance among coagulase-negative staphylococc i was observed in four intensive care units of a Parisian hospital. Tw enty-three such isolates, as well as 25 pristinamycin-susceptible Stap hylococcus epidermidis isolates, were collected and typed by analyzing various bacterial constituents. Two structurally related plasmids of 7.3 and 14.3 kb, carrying the gene vga encoding resistance to pristina mycin, were detected in the 23 pristinamycin-resistant coagulase-negat ive staphylococci which were identified as S. epidermidis. Although re lated by numerous common characteristics, 20 of these 23 isolates coul d be divided into two types, A (17 isolates) and B (three isolates). T hese types were characterized on the basis of their plasmid contents a nd hybridization patterns obtained when the EcoRI-digested DNA. was pr obed with plasmid pIP1551 containing an internal fragment of the inser tion sequence IS256. These findings suggest that the dissemination of type A epidemic strains was, in large part, responsible for the outbre ak.