Evaluation of the antimicrobial susceptibilities of coagulase-negative staphylococci by E-test.
Coagulase-negative staphylococci (CoNS) have recently emerged as important nosocomial pathogens. In this study, the susceptibility of 53 isolates of CoNS (42 S. epidermidis, 6 S. haemolyticus, 3 S. caprae, 1 S. lugdunensis and 1 S. chromogenes) obtained over a 1 year period at a Brazilian Hospital were tested for vancomycin, teicoplanin, cephalothin, penicillin, oxacillin, and chloramphenicol. The minimal inhibitory concentration (MICs) were determined by the E-test using saturated swabs or the flooding method. No isolates showed resistance to vancomycin, 3 (5.7%) were resistant to teicoplanin, 5 (9.4%) to cephalotin, most of them, (47, 88.6%) were resistant to penicillin, 19 (35.8%) to oxacillin and 27 (50.9%) to chloramphenicol. The study shows that the increased resistance of CoNS can cause serious infections of difficult treatment. The E-test proved to be a convenient and reliable method for MIC determination of CoNS isolates and the qualitative and quantitative results obtained by flooding were much more reproducible than the results obtained using swabs.
Department of Clinical, Toxicologic and Bromatologic Analyses, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Brasil.
C
C
Barelli
E C
EC
Minto
R
R
Martinez
A L
AL
Darini
D001426:Bacterial Proteins / Q000032:analysis*; D003030:Coagulase / Q000032:analysis*; D004058:Diffusion; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests / Q000295:instrumentation*; D011934:Reagent Strips; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification
D001426:Bacterial Proteins; D003030:Coagulase; D011934:Reagent Strips