Plasmid profiles and restriction enzyme fragmentation patterns of plasmids of methicillin-sensitive and methicillin-resistant isolates of Staphylococcus aureus from hospital and the community.
The number, frequency distribution and restriction enzyme fragmentation patterns of plasmids harboured by 163 methicillin-sensitive isolates of Staphylococcus aureus (MSSA) and 53 methicillin-resistant isolates (MRSA) were compared. Plasmids were demonstrated in less than half of the MSSA isolates; their frequency distribution did not differ from that predicted by a simple model of plasmid distributions. In contrast, all the MRSA isolates harboured plasmids, their distribution suggesting dissemination of a limited number of clones within the hospital. Among 72 MSSA isolates harbouring plasmids, 38 different restriction patterns were identified. There were fewer patterns among MRSA isolates; 11 were observed, and two predominant patterns accounted for 68% of those identified. These restriction patterns correlated with the presence or absence of aminoglycoside resistance. A multicopy plasmid of 2.6 kb was present in both MSSA and MRSA isolates that harboured more than one plasmid; it had the same restriction pattern irrespective of its source. The importance of these results in choosing a method of studying the spread of staphylococci is discussed.
Coia
J E
JE
University Department of Bacteriology, Glasgow Royal Infirmary.
Noor-Hussain
I
I
Platt
D J
DJ
D003428:Cross Infection / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis*; D006801:Humans; D008712:Methicillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D010957:Plasmids; D015183:Restriction Mapping; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
D004269:DNA, Bacterial; D008712:Methicillin