Susceptibilities of 201 anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin by oxyrase agar dilution and E test methodologies

The susceptibility of 201 anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin was tested by agar dilution and E test methods by using a commercially available plate and dish system (OxyDish) to provide anaerobic conditions. Plates were incubated for 48 h. MICs for 50% of strains tested and MICs for 90% of strains tested by agar dilution and E test methods corresponded within 1 doubling dilution for all compounds. When all antibiotics were considered together, agar and E test MICs were within 1 and 2 doubling dilutions of each other in 84 to 91% and > 99% of cases, respectively.