Fungal yield from sterile specimens.

Area of Science:

• Medical Mycology
• Clinical Microbiology
• Diagnostic Laboratory Science

Background:

• Clinician-ordered fungal cultures are often not requested even when indicated.
• Sterile specimens are routinely cultured for bacteriology, but fungal detection may be missed.
• Current diagnostic approaches may underdiagnose fungal infections in sterile sites.

Purpose of the Study:

• To evaluate the incremental yield and cost-effectiveness of routine fungal cultures for sterile specimens.
• To determine the rate of fungal identification when Sabouraud dextrose agar (SAB) plates are routinely incubated alongside bacteriology media.
• To assess the clinical significance of fungi detected solely through routine incubation.

Main Methods:

• A retrospective analysis of 44,635 sterile specimens cultured between 2011 and 2016.
• Comparison of fungal detection rates from specific fungal requests, routine bacteriology media, and routine Sabouraud dextrose agar (SAB) plates.
• Assessment of the clinical significance and treatment of positive fungal cultures.

Main Results:

• Fungi were identified in 2.3% of all sterile specimens.
• Routine incubation of SAB plates yielded fungi in 0.4% of specimens, with 77 of these considered clinically significant.
• Relying on clinician requests alone resulted in underdiagnosis, missing 171 cases detected by routine SAB incubation.

Conclusions:

• Routine fungal culture of sterile specimens provides a modest incremental yield beyond standard bacteriology and specific requests.
• The practice of routinely incubating SAB plates for sterile specimens can improve the detection of clinically significant fungal infections.
• The cost-effectiveness of routine fungal cultures warrants careful consideration, balancing diagnostic yield against financial expenditure.