LABILE ANTIBIOTIC-RESISTANCE IN STAPHYLOCOCCUS-AUREUS

Twenty-two isolates of Staphylococcus aureus, recovered from patients over a period of about one year, exhibited low level resistance to mup irocin, developed a salmon pink colour on culture and 21 had the same phage-type. However the plasmid profiles and associated antibiotic res istances differed. Digestion of cellular DNA with SmaI showed that two isolates from a single patient had a markedly different pattern to th e remainder, and that six others differed by one band, though these fo rmed groups of one and five isolates. This episode apparently represen ts a small outbreak of colonization or infection, which would have bee n missed but for the unusual pigmentation of the isolates recovered, a nd illustrates the difficulties of relying on a single typing system.