RESUMEN
BACKGROUND: Azole-resistant Aspergillus fumigatus (ARAf), reported as a global public health concern, has been unexpectedly observed in different countries. AIM: To identify ARAf and detect azole resistance related to the CYP51A mutation in different hospital environmental samples. METHODS: In this multi-centre study from Iran, surfaces of electronic equipment and appliances from different hospitals in Iran were sampled using cotton swabs. All samples were cultured using azole-containing agar plates (ACAPs). Recovered Aspergillus isolates were identified at the species level using partial DNA sequencing of the ß-tubulin gene. The azole susceptibility testing of A. fumigatus isolates was performed using the Clinical and Laboratory Standards Institute M38-A3 guideline. The sequencing of the CYP51A gene was also performed to detect mutations related to resistance. FINDINGS: Out of the 693 collected samples, 89 (12.8%) Aspergillus species were recovered from ACAPs. Aspergillus fumigatus (41.6%) was the most prevalent, followed by A. tubingensis (23.6%) and A. niger (15.6%). Among 37 isolates of A. fumigatus, 19 (51.3%) showed high minimum inhibitory concentration (MIC) values to at least one of the three azoles, voriconazole, itraconazole, and posaconazole. CYP51A polymorphisms were detected in all 19 isolates, of which 52.6% showed the TR34/L98H mutation. Other detected mutations were G432C, G448S, G54E/G138C, F46Y, and Y121F/M220I/D255E. T289F and G432C were the first reported mutations in ARAf. CONCLUSION: There was a considerable level of azole resistance in hospital environmental samples, a serious warning for patients vulnerable to aspergillosis. Our findings have also revealed a different mutation pattern in the CYP51A gene.
Asunto(s)
Aspergillus fumigatus , Azoles , Humanos , Aspergillus fumigatus/genética , Azoles/farmacología , Antifúngicos/farmacología , Antifúngicos/uso terapéutico , Irán/epidemiología , Proteínas Fúngicas/genética , Farmacorresistencia Fúngica/genética , Hospitales , Pruebas de Sensibilidad MicrobianaRESUMEN
AIMS: This study aimed to investigate the mechanism of antifungal action of Streptomyces libani dichloromethane extract fraction A (DCEFA) against Aspergillus fumigatus and the host cytotoxicity. METHODS AND RESULTS: DCEFA was purified from S. libani by autobiography and showed strong antifungal activity against A. fumigatus. A combination of electron microscopy, cell permeability assays, total oxidant status (TOS) assay, cell cytotoxicity assay and haemolysis activity was carried out to determine the target site of DCEFA. Exposure of A. fumigatus to DCEFA caused the damage to membranous cellular structures and increased release of cellular materials, potassium ions and TOS production. DCEFA was bound to ergosterol but did not affect fungal cell wall and ergosterol content. DCEFA did not show any obvious haemolytic activity for RBCs and toxicity against HEK-293 cell line. CONCLUSIONS: DCEFA may inhibit A. fumigatus growth by targeting fungal cell membrane which results in the leakage of potassium ions and other cellular components, TOS production and final cell death. SIGNIFICANCE AND IMPACT OF THE STUDY: DCEFA of S. libani could be considered as a potential source of novel antifungals which may be useful for drug development against A. fumigatus as a life-threatening human pathogen.