Comparison of three methods for anaerobe identification.

Area of Science:

• Clinical microbiology
• Bacteriology

Background:

• Accurate identification of anaerobic bacteria is crucial for patient care.
• Several commercial identification systems exist, but their performance varies.

Purpose of the Study:

• To evaluate the accuracy of three commercial identification methods: API 20A, Minitek, and Anaerobe-Tek.
• To compare their performance without supplemental tests or gas-liquid chromatography.

Main Methods:

• 165 recent clinical and 38 stock isolates of anaerobic bacteria were tested.
• Three commercial systems (API 20A, Minitek, Anaerobe-Tek) were used according to manufacturer instructions.
• No supplemental tests or gas-liquid chromatography were employed.

Main Results:

• API 20A achieved 70.0% species-level identification, Minitek 69.5%, and Anaerobe-Tek 64.0%.
• Anaerobe-Tek had the highest misidentification rate (14.8%), while API 20A had 6.4% and Minitek 13.8%.
• For common species like Bacteroides fragilis and Clostridium perfringens, all systems provided accurate information.

Conclusions:

• API 20A and Minitek are preferred for extensive anaerobic bacteria identification.
• Anaerobe-Tek is suitable for identifying clinically significant species when gas-liquid chromatography is unavailable.
• All systems have limitations and associated error rates that laboratories should consider.