Apparent colistin-related false sensitivity with the Autobac I system

Area of Science:

• Microbiology
• Clinical Diagnostics
• Antimicrobial Susceptibility Testing

Background:

• The Autobac I system is utilized for microbial identification and susceptibility testing.
• Antibiotic-free chambers are employed in certain diagnostic protocols.
• False positive results can impact patient care and antimicrobial stewardship.

Purpose of the Study:

• To investigate the occurrence and potential cause of false sensitivities in antibiotic-free Autobac I chambers.
• To identify the specific antimicrobial agent implicated in this phenomenon.

Main Methods:

• Observational analysis of Autobac I system performance.
• Review of susceptibility testing data from antibiotic-free chambers.
• Correlation of false sensitivity events with specific antibiotic usage or characteristics.

Main Results:

• Occasional false sensitivities were detected in antibiotic-free Autobac I chambers.
• The phenomenon was observed randomly across various gram-negative bacilli.
• A correlation was identified between these false sensitivities and the antibiotic colistin.

Conclusions:

• Colistin may be associated with false sensitivities in antibiotic-free Autobac I chambers.
• Further investigation is warranted to understand the mechanism of this colistin-related effect.
• Clinical laboratories should be aware of this potential artifact during interpretation of results.