ABSTRACT
Background Fungal infections mainly caused by Candida krusei are increasing rapidly and represent a serious public health problem in human immunodeficiency virus (HIV)-infected patients. This study aimed to investigate the antifungal susceptibility profile and virulence factors in C. krusei isolated from HIV-infected patients. Methodology Isolates were identified by biochemical and molecular methods. The antifungal resistance profile was established based on the antifungal susceptibility test performed using the Sensititre YeastOne™ (Thermo Fisher Scientific, Waltham, MA) microdilution technique. The production of phospholipase and proteinase was detected by standard methods. Biofilm formation was performed by the microtiter plate method. Results A total of 73 isolates of C. krusei were recovered from stool, oral swabs, vaginal swabs, and urine samples. The highest number of C. krusei isolates (49, 67.05%)was recovered from stool samples. A total of 32.56% of the C. krusei isolates were multidrug-resistant (MDR). The patients living with HIV and not receiving antiretroviral treatment displayed the highest number of C. krusei isolates (29, 39.76%), whereas the patients living with HIV on antiretroviral therapy exhibited the lowest number of C. krusei isolates (2, 2.72%). All isolates were categorized as strong biofilm producers. Among the production of hydrolytic enzymes, 25 (58.13%) and 24 (55.81%) of C. krusei isolates were classified as strong phospholipase and proteinase producers, respectively. Conclusion The C. krusei isolates obtained in this study were MDR and strongly expressed biofilm formation and both phospholipase and proteinase hydrolytic enzymes. The results show how pathogenic C. krusei is in the HIV-infected population and will contribute toward the management of C. krusei-related infections, which may help improve the life quality of people living with HIV.
ABSTRACT
BACKGROUND: Candida tropicalis is a human pathogenic yeast frequently isolated in Latin America and Asian-Pacific regions, although recent studies showed that it is also becoming increasingly widespread throughout several African and south-European countries. Nevertheless, relatively little is known about its global patterns of genetic variation as most of existing multilocus sequence typing (MLST) data come from Asia and there are no genotyped African isolates. OBJECTIVES: We report detailed genotyping data from a large set of C. tropicalis isolates recovered from different clinical sources in Italy, Egypt and Cameroon in order to expand the allele/genotype library of MLST database (https://pubmlst.org/ctropicalis), and to explore the genetic diversity in this species. METHODS: A total of 103 C. tropicalis isolates were genotyped using the MLST scheme developed for this species. All isolates were also tested for in vitro susceptibility to various antifungals to assess whether certain genotypes were associated with drug-resistance. RESULTS AND CONCLUSIONS: A total of 104 different alleles were detected across the MLST-loci investigated. The allelic diversity found at these loci resulted in 51 unique MLST genotypes of which 36 (70.6%) were novel. Global optimal eBURST analysis identified 18 clonal complexes (CCs) and confirm the existence of a specific Italian-cluster (CC36). Three CCs were also statistically associated with fluconazole resistance, which was elevated in Cameroon and Egypt. Our data show high genetic diversity in our isolates suggesting that the global population structure of C. tropicalis is still poorly understood. Moreover, its clinical impact in Italy, Egypt and Cameroon appears to be relevant and should be carefully considered.
