Antimicrobic susceptibility and plasmid profile analysis as identity tests for multiple blood isolates of coagulase-negative staphylococci.
We compared a disk diffusion antimicrobic susceptibility panel with plasmid DNA profiles as tests for identity of 106 isolates of coagulase-negative staphylococci cultured from the blood of 45 patients on multiple occasions. The antimicrobic panel included penicillin, oxacillin, clindamycin, trimethoprim-sulfamethoxazole, chloramphenicol, tetracycline, tobramycin, kanamycin, and gentamicin. Nineteen patterns of antimicrobic susceptibility were found. The most common pattern was present in 25% of the isolates, and at least one isolate from 31% of the patients had this pattern. Forty-seven distinct plasmid DNA profiles were found. The most common plasmid profile was present in 8.5% of the isolates, and at least one isolate from 15% of the patients had this profile. Twenty-eight patients had multiple isolates that were identical by plasmid profile analysis. Twenty-seven (96%) of these patients had isolates that were also identical by antimicrobic susceptibility. Nineteen patients had multiple isolates that were different by plasmid profile analysis. In 18 (95%) of these patients, the isolates were also different by antimicrobic susceptibility. Although plasmid DNA profile analysis is a more discriminating tool, these data confirm that a selected disk diffusion antimicrobic susceptibility panel may be used to screen multiple blood isolates of coagulase-negative staphylococci for identity or differences.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001769:Blood / Q000382:microbiology*; D003030:Coagulase; D004269:DNA, Bacterial / Q000032:analysis; D004587:Electrophoresis, Agar Gel; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D013210:Staphylococcus / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D003030:Coagulase; D004269:DNA, Bacterial