Use of chemiluminescent DNA probes in the rapid detection of oxacillin resistance in clinically isolated strains of Staphylococcus aureus

Gary R. Youmans, Thomas E. Davis, De Anna D. Fuller

Research output: Contribution to journalArticle

6 Scopus citations


Chemiluminescent DNA probes (AccuProbe, species specific; and FlashTrack, bacterial generic) were used to determine oxacillin resistance in Staphylococcus aureus. Ribosomal RNA was measured at designated intervals in the presence and absence of antibiotic. A total of 48 (AccuProbe assay) and 24 (FlashTrack) S. aureus isolates with known oxacillin susceptibility patterns were inoculated into Bactec 6A bottles both with and without 4 μg/ml oxacillin and incubated at 35°C for 4 h. Aliquots were removed at 0 and 4 h, and pellets of bacteria were obtained via selective centrifugation. Probe assay counts (relative light units, RLUs) were performed. Of 21 oxacillin-resistant S. aureus (ORSA) strains, 20 showed a >5-fold RLU increase during the incubation period (AccuProbe assay): 25 of 27 oxacillin-susceptible strains demonstrated a ≤4-fold increase. AccuProbe test sensitivity and specificity were 95% and 92%, respectively. With the generic FlashTrack probe assay, all nine ORSA isolates showed a ≥4-to 10-fold increase in RLUs, and all 15 oxacillin-susceptible strains showed a ≤4-fold increase in RLUs during the 4-h incubation. The FlashTrack test sensitivity and specificity were both 100%. Probe assays were completed within 5 h. This study suggests that rapid and reliable determination of oxacillin resistance in S. aureus clinical isolates can be accomplished using commercially available DNA probes.

Original languageEnglish (US)
Pages (from-to)99-104
Number of pages6
JournalDiagnostic Microbiology and Infectious Disease
Issue number2
StatePublished - Feb 1993


ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

Cite this