Isolation And Analysis Of Clinical Aspergillus Fumigatus And Penicillium Strains In Guangxi

In recent years,the incidence of invasive fungal infection has increased with the increasing number of immunocompromised patients with HIV/AIDs,cancer patients undergoing radiation chemotherapy,and patients receiving immunosuppressant therapy after solid organ transplant.Aspergillus spp.,Candida spp.,Cryptococcus spp.and Mucor spp.are the most prevalent pathogenic fungi causing invasive fungal infections.Among Aspergillus spp.species,A.fumigatus is the most common pathogen.A.fumigatus is a saprophytic fungus,widely distributed in environment,with high temperature tolerance(>48℃).Guangxi is an area with a high incidence of fungal infections.Azoles and amphotericin B are used as the first line treatment for fungal infections.The emergence of resistant A.fumigatus strains to these drugs has been reported worldwide,however,the reports are very limited in China.In this study,we investigated the frequency of drug resistance of clinical A.fumigatus strains isolated in Guangxi.By testing the sensitivities of clinical isolates to three antifungal drugs,we only found three azole-resistance A.fumigatus isolates,with a drug resistance rate of 1.49%.One of the clinical isolate showed good resistance to voriconazole and itraconazole,and the comparison showed that the promoter region of its cyp51 A gene had one base mutation.On the contrary,amphotericin B-resistance was more common,accounting for 6.97%(n=201).These results suggest that amphotericin B is the most prevalent drug used for clinical treatment in Guangxi and should be used more carefully.In addition,during the isolation of A.fumigatus strains we also isolated two strains that are not tolerant to high temperature.Using both morphological and molecular methods,these two strains were identified as Penicillium oxalicum and Penicillium citrinum,respectively.Both P.oxalicum and P.citrinum isolates were resistant to azole drugs and amphotericin B.In the infection model of Caenorhabditis elegans,their toxicity was stronger than the P.oxalicum isolated from the environment.Our results suggest that these two clinical isolates are different from the environmental isolate with pathogenicity that probably derived from the adaptive evolution in human host.In summary,our investigation here provides a useful information and guidance for clinical diagnosis and treatment of invasive fungal infections in Guangxi area.At the same time,it provides effective data support for monitoring fungal resistance in China.