Laboratory study evaluates antifungal susceptibility of Aspergillus from Costa Rican coffee beansLab study finds coffee bean fungi often resist common antifungal drugs

Frontiers in Medicine Published May 20, 2026 DOI ↗ Editorial oversight: Dr. Sofia Müller, MD · Lifespan & Whole-Person Care

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Key Takeaway

Note variability in antifungal MICs for Aspergillus from Costa Rican coffee beans.

This laboratory study evaluated the antifungal susceptibility of Aspergillus spp. isolated from coffee beans in the Los Santos coffee-growing region of Costa Rica. The investigation included 187 isolates and assessed minimal inhibitory concentration (MIC) and wild-type classification for amphotericin B, itraconazole, and voriconazole. No comparator was reported, and the setting was restricted to this specific agricultural context.

The mean MIC for amphotericin B was 2.77 ± 3.19 µg mL−1. For itraconazole, the mean MIC was 0.29 ± 0.26 µg mL−1. The mean MIC for voriconazole was 1.14 ± 2.68 µg mL−1. Non-wild-type classification for amphotericin B was observed in 15.2% of A. flavus, 75.0% of A. fumigatus, and 3.5% of A. niger. Non-wild-type classification for voriconazole was 4.3% in A. flavus/oryzae and 25.0% in A. fumigatus.

The authors note that these results will be useful to define appropriate policies in the use of these drugs both in the clinical area and in agriculture. Safety data, including adverse events, were not reported. The study does not establish causal links between agricultural exposure and clinical outcomes, and the findings are specific to the sampled population.

Scientists in Costa Rica tested fungi found on coffee beans to see how they reacted to common antifungal drugs. They analyzed 187 samples of Aspergillus species collected from the Los Santos coffee-growing region. The goal was to check how sensitive these fungi were to medicines like amphotericin B, itraconazole, and voriconazole.

The results showed that some fungi were harder to treat than expected. For example, 75% of the Aspergillus fumigatus samples were classified as non-wild type for amphotericin B, meaning they showed reduced sensitivity. Similarly, 25% of Aspergillus fumigatus samples were non-wild type for voriconazole. The average amounts of drug needed to stop fungal growth varied significantly between the different medicines tested.

This laboratory study did not involve people, so no safety concerns for patients were reported. However, the findings suggest that current drug policies might need updating. These results could help guide how doctors use these drugs in clinical settings and how farmers manage fungi in agriculture. Because this was a lab study with a limited number of samples, the results apply only to the specific fungi tested in that region.

What this means for you:

Lab testing shows coffee bean fungi often resist standard antifungal drugs, suggesting a need for updated drug policies.

Study Details

Study typeGuideline

EvidenceLevel 5

PublishedMay 2026

View Original Abstract ↓

The indiscriminate use of fungicides in agricultural crops is considered one of the most important causes of antifungal resistance. Hence, it is our interest to contribute to the knowledge of antifungal resistance, within the framework of One Health. The results will be useful to define appropriate policies in the use of these drugs both in the clinical area and in agriculture. Thus, the susceptibility patterns of 187 Aspergillus spp. (A. flavus [n = 46], A. fumigatus [n = 8], A. insuetus [n = 1]; A. niger [n = 85], A. tamarii [n = 34] and Aspergillus section Versicolores [n = 13]), isolated from coffee beans from the Los Santos coffee-growing region in Costa Rica, were evaluated for amphotericin B (AMB), itraconazole (ITZ) and voriconazole (VRC); using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution M38 guideline. The mean minimal inhibitory concentration (MIC) for AMB was 2.77 ± 3.19 μg mL−1, 0.29 ± 0.26 μg mL−1 for ITZ, and 1.14 ± 2.68 μg mL−1 for VRZ. Based on the CLSI guidelines, 15.2% of A. flavus, 75.0% of A. fumigatus and 3.5% of the A. niger were classified as non-wild type for AMB; 4.3% of the A. flavus/oryzae and 25.0% of the A. fumigatus were classified as non-wild type for VRC. ITZ presented the lowest MIC distribution, and the isolates were classified as wild-type strains. The results show a high susceptibility to ITZ, moderate to VRC (treatment of choice for invasive aspergillosis) and low susceptibility to AMB.

Laboratory study evaluates antifungal susceptibility of Aspergillus from Costa Rican coffee beansLab study finds coffee bean fungi often resist common antifungal drugs

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