A comparative study on antifungal susceptibility of Penicillium marneffei (Talaromyces marneffei) and nonmarneffei Penicillium species

Abstract

Background: The fungus Penicillium can cause various infectious diseases in humans and animals. Being present in the environment, its importance in human health has been neglected and is often interpreted as room contaminant. Treatment of regional penicilliosis caused by dimorphic Penicillium marneffei has been according to the protocol available in literature. Objective: The study was conducted to determine the antifungal susceptibility pattern of endemic P. marneffei and other nonmarneffei (NM) Penicillium species in Manipur. Materials and Methods: Clinical and environmental Penicillium species were isolated using standard operating procedure. Antifungal susceptibility of five antifungal agents, namely amphotericin B, voriconazole, itraconazole, fluconazole, and natamycin, was carried out according to the Clinical and Laboratory Standards Institute (CLSI, M38–A2) guidelines. Results: All P. marneffei isolates (100%) showed sensitivity to amphotericin B at ≤1 μg/ml, whereas 96.5% and 76.3% of clinical and environmental NM Penicillium isolates, respectively, were sensitive at ≤1 μg/ml. Clinical isolates were completely inhibited at a concentration of ≤0.25 μg/ml of voriconazole. 30.7% P. marneffei were susceptible at lower minimum inhibitory concentration (MIC) of 0.06 μg/ml of itraconazole, but 31.4% of environmental isolates noted a high MICs of ≥0.5 μg/ml. There was no significant difference in fluconazole MIC among tested strains; however, 10.5% of environmental strains noted higher MIC at 150 μg/ml. 16 μg/ml of natamycin inhibited 100%, 86.2%, and 84.2% of P. marneffei and clinical and environmental NM Penicillium species, respectively. Conclusion: Itraconazole and voriconazole are the drugs of choice for the management of infection caused by P. marneffei and NM Penicillium species. Environmental NM Penicillium isolates with higher MICs may be because of exposure to agricultural fungicides.