Adaptation of an Automated Microbiology System for the Growth of Anaerobes and Performance of Antimicrobial Susceptibility Tests

Abstract

The authors examined the feasibility of growing anaerobes in an automated microbiology system (MS-2) and using the system for antimicrobial susceptibility testing. A total of 78 of 100 clinical anaerobic isolates grew in the MS-2 if 100 μL of an undiluted overnight suspension of organisms was inoculated into at least 2.5 mL of freshly prepared Wilkins-Chalgren broth supplemented with 0.07% agar. Susceptibility test results were determined with 50 anaerobes tested against seven antibiotics in the MS-2 system and were compared with results determined with a qualitative reference susceptibility test method. Of the 350 tests, 88% of the MS-2 results agreed with the qualitative reference results. False-susceptible and false-resistant results were reported for 8.6 and 3.4%, respectively, of the MS-2 results.