Cultures for acid-fast bacilli: are we being good stewards?

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Clinical Pathology

Background:

• Acid-fast bacilli (AFB) cultures are essential for diagnosing mycobacterial infections.
• However, the appropriate utilization of AFB cultures in clinical practice requires careful consideration.

Purpose of the Study:

• To evaluate the utilization of AFB cultures in a healthcare system.
• To identify clinical scenarios where AFB cultures are unlikely to yield beneficial results.

Main Methods:

• A retrospective descriptive study was conducted on AFB cultures submitted to a microbiology laboratory over a two-year period.
• Data included patient demographics, ordering service line, specimen source, and culture results, extracted from electronic medical records.

Main Results:

• Over 13,944 AFB cultures were analyzed from 8,243 patients, with a 4.72% positive rate.
• A significant number of cultures, particularly from bone specimens (0.48% positive), were ordered in non-indicative clinical scenarios.
• Processing these cultures required substantial laboratory resources, equivalent to two full-time technicians.

Conclusions:

• A considerable proportion of AFB cultures are ordered without clear clinical indication for mycobacterial disease.
• Establishing specific testing criteria for AFB cultures can optimize resource allocation and reduce unnecessary healthcare expenditures.