Determination of antifungal susceptibility patterns among the environmental isolates of Aspergillus fumigatus in Iran

Does Prolonged Exposure of Environmental Fungi to Ultraviolet Irradiation Change the Pattern of Drug Resistance?

Background: The pathogenic and opportunistic fungal species cause life-threatening infections in immunocompromised patients. The ultraviolet (UV) germicidal irradiation is a well-known method for inactivating a significant number of microorganisms and has wide application for sterilization. Objectives: This study aimed to investigate the effect of ultraviolet C (UV-C) irradiation on the antifungal susceptibility pattern of some filamentous fungi. Methods: The effect of UV-C on the antifungal susceptibility pattern of itraconazole, voriconazole, fluconazole, and amphotericin B against filamentous fungi was examined. Changes in the morphological features of resistant strains following UV-C irradiation were also evaluated using scanning electron microscopy. Results: The results revealed a significant decrease in the number of the surviving spores of strains with the prolongation of UV-C irradiation (0 - 10 to 20 min; P < 0.05). Concerning the morphology of resistant Aspergillus spp., the results of scanning electron microscopy showed a significant increase in the length of irradiated hyphae compared to the non-irradiated hyphae (P < 0.05). In addition, colony count showed a significant decrease (P < 0.05). The findings revealed that UV-C radiation exposure could alter the antifungal susceptibility pattern of Aspergillus spp., such as increasing the minimum inhibitory concentration. Conclusions: Aspergillus spp. can cause systemic infections among lab technicians exposed to different doses of radiation. Moreover, this increase in susceptibility pattern can directly affect the duration of treatment.

Isolation and Characterization of Clinical Triazole Resistance Aspergillus fumigatus in Iran

BACKGROUND

Aspergillus fumigatus is a major cause of allergic syndromes, aspergilloma and life-threatening invasive infections in immunocompromised hosts. To date, a wide range of mutations in A. fumigatushave been described conferring azole-resistance, which commonly involves modifications in the cyp51A-gene (substitutions at codons G54, G138, P216, F219, M220, G448 and specifically codon L98 in combination with a 34-bp tandem repeat in the promoter region of the gene), the target for azole antifungals. We investigated the prevalence of azole-resistance in clinical A. fumigatus isolates obtained from patients in Iran during 2010 to 2014.

METHODS

Overall, 172 clinical A. fumigatus isolates obtained from patients with underlying disease including transplantation, granulocytopenia, chronic liver disease, chronic obstructive pulmonary disease (COPD) and allergic bronchopulmonary aspergillosis (ABPA). Samples were collected between Jan 2009 and Nov 2014 from five provinces of Iran (Tehran, Shiraz, Isfahan, Khorasan razavi and East Azerbaijan). Antifungal susceptibility test was determined according to EUCAST reference method for itraconazole (ITC), voriconazole (VRC) and posaconazole (POS). All isolates were confirmed by amplification of the partial tubulin gene.

RESULTS

Of 172 A. fumigatus isolates tested, six isolates (3.5%) had high MIC values of ITC (>16 mg/L) and VRC (≥4 mg/L). All six isolates showed a multi-resistant phenotype with high MICs of ITC and VRC.

CONCLUSION

We determined in-vitro susceptibility a profile of 172 clinically isolates of A. fumigatus against triazole in Iran. Azole-resistance is an emerging problem in A. fumigatus and international surveillance is warranted.