Micro-Media Systems anaerobe panel versus broth disk method in anaerobe antimicrobial testing

Area of Science:

• Microbiology
• Clinical Diagnostics
• Antimicrobial Resistance

Background:

• Accurate antimicrobial susceptibility testing (AST) is crucial for guiding treatment of anaerobic bacterial infections.
• Traditional methods can be labor-intensive and time-consuming.
• Novel AST methods require rigorous validation against established standards.

Purpose of the Study:

• To evaluate the performance of frozen microtitration trays from Micro-Media Systems (MMS) for anaerobic bacterial AST.
• To compare the MMS method with the established Virginia Polytechnic Institute (VPI) broth disk elution method.
• To assess the accuracy and reliability of MMS panels for key antibiotics.

Main Methods:

• Frozen microtitration trays (MMS) and VPI broth disk elution methods were used.
• 224 clinical anaerobic isolates were tested against carbenicillin, cefoxitin, chloramphenicol, clindamycin, penicillin, and tetracycline.
• Aerobic inoculation procedures were followed for both methods.

Main Results:

• MMS method achieved 74% growth performance compared to 89% for the VPI method.
• Overall discrepancy rate was 2.9% across 972 drug-organism combinations.
• Clindamycin and tetracycline accounted for 82% of all discrepancies.

Conclusions:

• MMS frozen microtitration trays offer a viable alternative for anaerobic bacterial AST.
• The MMS method is easy to inoculate and interpret.
• The MMS method demonstrates good comparative performance with the VPI broth disk elution method, with minor discrepancies primarily linked to specific antibiotics.