Low-level resistance to glycopeptides amongst staphylococcus species: surveillance in a university hospital and evaluation of a vancomycin screening agar.
The prevalence of low-level resistance to glycopeptides (teicoplanin MIC > or = 8 microg/mL and vancomycin MIC > or = 4 microg/mL) among staphylococci was investigated over a 15 month period. A total of 2,279 isolates (1,519 S. aureus, 760 coagulase-negative staphylococcus (CNS)) were screened using inoculum of 10(6) CFU/mL and Mueller-Hinton agars supplemented with 8 microg/mL of teicoplanin. Of these, 218 isolates (136 S. aureus and 82 CNS) grew on the screening agar. For these isolates, teicoplanin and vancomycin MICs were determined by agar dilution method and a vancomycin agar screening method was evaluated. The prevalence of low-level resistance to teicoplanin and vancomycin was 7.8% and 0.1% for S. aureus and 8.8% and 0.8% for CNS, respectively. The brain heart infusion agar containing 4 microg/mL of vancomycin failed to detect two out of eight staphylococcal isolates with vancomycin MICs of 4 microg/mL. Furthermore, the method appeared to lack reproducibility. Considering the increasing incidence of vancomycin treatment failure in staphylococcal infection, a more reliable screening method is required.
Park
Y J
YJ
Department of Clinical Pathology, College of Medicine, the Catholic University of Korea, Kangnam St. Mary's Hospital, Seoul, South Korea. yjpk@cmc.cuk.ac.kr
Jun Park
J
J
Lee
S O
SO
Oh
E J
EJ
Kee Kim
B
B
D000362:Agar; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D011159:Population Surveillance; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D017334:Teicoplanin / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D017334:Teicoplanin; D014640:Vancomycin; D000362:Agar