S. Davies et Pm. Zadik, COMPARISON OF METHODS FOR THE ISOLATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS, Journal of Clinical Pathology, 50(3), 1997, pp. 257-258
The control of methicillin resistant Staphylococcus aureus (MRSA) reli
es on the rapid and sensitive detection of carriage. The roles of an e
nrichment broth, duration of incubation, and Baird-Parker medium conta
ining ciprofloxacin (BPC) were evaluated in comparison with standard m
edia in a centre where the prevalence of ciprofloxacin resistance amon
g MRSA is over 98%. Screening swabs from 402 sites were plated onto BP
C, mannitol salt agar (MSA), and MSA with methicillin (MMSA). The swab
s were enriched in Tryptone-T broth with 6% salt for 24 hours and the
broths subcultured onto BPC, MSA, and MMSA. MRSA was isolated from 134
swabs. Significantly more isolates were obtained by incubating cultur
e plates for 42 hours rather than 18 hours, by the use of broth enrich
ment, and by addition of methicillin or ciprofioxacin to media. BPC wa
s the most sensitive medium (107 isolates (80%) by direct culture at 4
2 hours), grew the fewest contaminants, and allowed provisional report
ing of 73% of isolates at 18 hours by colonial appearance and use of S
taphaurex Plus rapid latex reagent. This may allow the introduction of
infection control measures a day earlier than when other established
methods are used.