MOLECULAR CHARACTERIZATION OF CANDIDA SPECIES ISOLATES RECOVERED FROM CLINICAL SPECIMENS IN PALESTINE

Abstract

Background: Candida species are major opportunistic fungal pathogens commonly associated with severe infections. While C. albicans remains the most prevalent and virulent species, the clinical importance of non-albicans Candida species has substantially risen. Objectives: This study investigated Palestinian clinical isolates of Candida species by identifying their species type, genotype, mating type, and biofilm-forming capability, and by detecting virulence factors using polymerase chain reaction (PCR), besides C. albicans strains genetic heterogeneity. Methodology: One hundred clinical Candida isolates were obtained from four medical governmental hospitals in central and northern Palestine. The PCR technique was used to identify the Candida species and the ABC genotype for the 25S rDNA. The mating type was also determined, in addition to the detection of hyphal wall protein 1, agglutinin-like sequence genes, phospholipases, and secreted aspartic proteases. Genetic heterogeneity among C. albicans strains was determined by RAPD-PCR typing. Results: C. albicans (n=53/100, 53%) and C. tropicalis (n=15/100, 15%) were the most prevalent species, followed by C. krusei (n=13/100, 13%), C. glabrata (n=5/100, 5%), and mixed species of C. krusei and C. glabrata (n=3/100, 3%), C. albicans and C. glabrata (n=1/100,1%), and the remaining haven't shown any bands (10/100,10%). Genotype A was the most prevalent among C. albicans isolates (n=17/53, 27%), followed by genotype B (n=16/53, 30%), genotype C (n=7/53, 13%), and the remaining isolates showed no genotype bands (n=13/53, 25%). Notably, 15 isolates of C. albicans showed MTLa homozygosity (n=15/53, 28), and one isolate among C. tropicalis (n=1/15, 7%). Agglutinin-like sequence genes are present in 59% of the isolates. In addition, the SAP9 and/or SAP10 genes were found in high percentages among Candida spp. including: C. glabrata (n=4/5,80%), C. albicans (n=33/53,66%), C. krusei (n=8/13,61.5), and C. tropicalis (n=9/15, 60%). Therefore, the results of RAPD-PCR typing revealed that 14 fragments were produced with the OPI 06 primer, all of which were polymorphic. The 24 C. albicans isolates were clustered into four groups on a 50% cut-off similarity. Conclusion: C. tropicalis was the most frequently isolated non-albicans Candida species. Biofilm formation and the presence of SAP9 and/or SAP10 genes were mainly observed in C. albicans strains exhibiting low genetic variability.