PubMed · 6562961
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
R Lally, B Woolfrey. 1984. Clumping factor defective methicillin-resistant Staphylococcus aureus.. https://doi.org/10.1007/bf02014336
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Bacteria of the genus Staphylococcus are notoriously difficult to classify and identify; many routine hospital laboratories use only simple, older techniques to segregate them into broad groups. Recent studies have demonstrated that subspecific strains vary in their clinical significance and are of increasing importance in hospital-derived infections; this has led to a need for better methods of classification and identification. Restriction fragment length polymorphism analysis of genes for ribosomal RNA ('ribotyping') is potentially very useful since these genes occur in multiple copies in the genome, and are relatively stable. The restriction fragment patterns are sufficiently different to be usable in classification and identification. This paper considers an electrophoretic method for the separation of these restriction fragments which has the advantages of using a nonradioactive probe and a simple colour signal generating system for its evaluation. The technical principles are universal and would allow the procedure to be developed for other groups of microorganisms.
Explore the source record for details and available documents.
Current standards of the National Committee for Clinical Laboratory Standards (NCCLS) for microtube dilution recommend 24-hour incubation of staphylococci when testing for oxacillin/methicillin resistance. This study was conducted to quantify the need for this requirement. Standard 16-hour readings were compared with subsequent 24-hour readings of 515 fresh clinical isolates (256 Staphylococcus aureus, 259 coagulase-negative staphylococci) that were susceptible to oxacillin (microtube dilution minimum inhibitory concentration [MIC] < or equal to 2 micrograms/mL) after 16 hours. Five hundred two of the susceptible isolates (97.5%) were still susceptible at 24 hours. The remaining 13 isolates were resistant (MIC > 2 micrograms/mL) at 24 hours. Duplicate retesting, alternative method testing (Kirby-Bauer, E-Test) and mec A gene analysis were performed on these 13 isolates. All 13 isolates possessed the mec A gene. Four isolates always tested resistant (including all 16-hour repeat microtube dilution readings), and one isolate always tested susceptible. The remaining eight isolates produced variable results suggestive of an MIC very close to the resistance/susceptible break point. Overall , conversion from susceptible to resistant was entirely dependent upon the 16-hour MIC. There were 53 isolates with 16-hour MICS of 2 micrograms/mL. All 13 converters came from this group. No isolate with an oxacillin MIC < 2 micrograms/mL at 16 hours was resistant at 24 hours. Based on these results, the authors instituted a selective reincubation of only those staphylococcal isolates with oxacillin readings of 2 micrograms/mL at 16 hours.