TABLE 1.

Effects of various concentrations of erythromycin on detection of inducible clindamycin resistance by the agar dilution method

Erythromycin concn (mg/liter)aNo. of strains with genotype of:Agar dilution result% Sensitivityb% Specificityb
msrA only (n = 51)ermA and/or ermC (n = 176)
1510Negative100 (97.9-100)100 (93.0-100)
0176Positive
2513Negative98.3 (95.1-99.7)100 (93.0-100)
0173Positive
4515Negative97.2 (90.5-97.6)100 (93.0-100)
0171Positive
8519Negative94.9 (91.6-98.1)100 (93.0-100)
0167Positive
  • a The clindamycin concentration was 0.5 mg/liter with an inoculum concentration of 107 bacteria/ml.

  • b 95% confidence intervals are in parentheses.