Determination of Putative Aspergillus fumigatus and Aspergillus flavus Environmental Strains from Selected TB-DOTS Treatment Centers in Manila, Philippines

Background. Chronic pulmonary aspergillosis (CPA) is a significant complication among tuberculosis (TB) patients, with approximately 77,000 cases occurring annually in the Philippines. However, no published studies have examined Aspergillus presence or antifungal susceptibility patterns in TB-DOTS treatment centers.

Objective. This study aimed to determine the presence of putative Aspergillus fumigatus and A. flavus environmental strains in selected TB-DOTS centers in Manila and characterize their antifungal susceptibility profiles.

Methods. A cross-sectional study was conducted in three TB-DOTS centers in Manila, Philippines. Active air sampling was performed using a Six-Stage Andersen Air Sampler. Isolates were identified through macroscopic (culture) and microscopic morphological characteristics. Seventeen isolates (nine A. fumigatus, eight A. flavus) underwent the gradient diffusion method for antifungal susceptibility testing against amphotericin B, voriconazole, and caspofungin. Results were interpreted using CLSI M38M51S epidemiological cutoff values.

Results. A total of 22 A. fumigatus (mean: 25.91 CFU/m3) and 11 A. flavus (mean: 12.96 CFU/m3) were isolated across all three TB-DOTS centers. All tested isolates (17/17) were susceptible to voriconazole. For caspofungin, 23.53% (4/17) demonstrated resistance, with 75% (3/4) being A. flavus. Amphotericin B results were considered indeterminate due to unexpected resistance in the positive control.

Conclusion. This study provides initial data on the presence and antifungal susceptibility patterns of environmental A. fumigatus and A. flavus in Philippine TB-DOTS centers. The universal susceptibility to voriconazole is encouraging and supports its continued use as first-line therapy for aspergillosis. However, the emergence of caspofungin resistance warrants ongoing surveillance. These findings emphasize the need for environmental monitoring and national fungal concentration air quality guidelines in Philippine healthcare facilities to protect the immunocompromised population from opportunistic infections like healthcare-associated aspergillosis.