Gram negative anaerobe susceptibility testing in clinical isolates using Sensititre and Etest methods

Antibiograms provide useful information for clinicians when choosing antimicrobials for infections caused by anaerobic organisms. This study has shown that in our area, use of metronidazole as a broad spectrum anti-anaerobic agent remains appropriate. Anaerobic susceptibility testing is also important to perform in individual clinical isolates, especially from sterile sites or in pure culture. The emergence of broad spectrum β-lactam and carbapenem resistance in clinical isolates of Bacteroides fragilis is of concern and will require further monitoring. The Etest method was considered superior to Sensititre trays given that the higher inoculum used may allow demonstration of heteroresistance, anaerobiasis can be maintained during setup, lower failure rates, and the ability to select only the antibiotics required.