The Journal of Medical Microbiology, Vol 27, Issue 4 271-276, Copyright © 1988 by Society for General Microbiology
Plasmid profiles and restriction enzyme fragmentation patterns of plasmids of methicillin-sensitive and methicillin-resistant isolates of Staphylococcus aureus from hospital and the community
J. E. Coia, I. Noor-Hussain and D. J. Platt
University Department of Bacteriology, Glasgow Royal Infirmary.
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.
