Investigation of Staphylococcus aureus isolates identified as erythromycin intermediate by the Vitek-1 System: comparison with results obtained with the Vitek-2 and Phoenix systems.
We identified 69 Staphylococcus aureus isolates that were erythromycin intermediate as reported by the Vitek-1 system using the GPS-105 card. Of the 57 strains that were available for further testing, all were erythromycin resistant by broth microdilution and the Phoenix system, while the Vitek-2 system identified 55 of 57 strains (96%) as erythromycin resistant. The majority of isolates (54 of 57 [95%]) exhibited the inducible MLS (macrolide-lincosamide-streptogramin family) phenotype, as shown by the double-disk test. We recommend that all S. aureus strains determined as erythromycin intermediate by the Vitek-1 system be interpreted as resistant to erythromycin.
Tang
Patrick
P
Department of Microbiology, Mount Sinai Hospital, and Toronto Medical Laboratories, Toronto, Ontario, Canada.
Low
Donald E
DE
Atkinson
Sandra
S
Pike
Karen
K
Ashi-Sulaiman
Aisha
A
Simor
Andrew
A
Richardson
Susan
S
Willey
Barbara M
BM
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000295:instrumentation / Q000379:methods; D011933:Reagent Kits, Diagnostic; D013211:Staphylococcus aureus / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D011933:Reagent Kits, Diagnostic; D004917:Erythromycin