Application of molecular techniques to study the etiology and epidemiology of Candida ssp. infections in Central Vietnam

The overall objective of this study was to apply a variety of molecular techniques to determine the etiology and epidemiology of Candida spp. infections in Central Vietnam. MALDI-TOF Mass Spectrometry correctly identified 94.9% of 196 Candida spp. isolated strains. The remaining unidentified species (5.1%) were detected by ITS gene amplification and sequencing. A variety of Candida species were isolated, with the most common species being C. albicans (47.96%), followed by C. tropicalis (16.33%), C. parapsilosis (10.71%), C. glabrat (8.67%), C. orthopsilopsis (5.61%), C. krusei (3.57%) and others species. Antibiotic susceptibility showed higher rates of resistance to fluconazole in C. tropicalis (56.67%). Two specific missense mutations in the ERG11 protein (Y132F and S154F) were detected from 26.67% of fluconazole resistant C. tropicalis isolates. 96.81% of C. albicans isolates carried all three virulence genes (als1, hwp1, sap4) regardless of the sample source, that was concordant with a higher frequency of C. albicans in mucosal candidiasis compared to a higher frequency of C. non albicans in candida colonizations. A total of 12 C. albicans diploid sequence types (DSTs) were identified from ten different wards by Multi Locus Sequence Typing (MLST). Of the 12 identified DSTs, six were new DSTs assigned by this study. Based on C. albicans cluster analysis, 66.67% of the isolates clustered with previously known clades in global or Asian data, and 33.33% isolates were singleton. MLST results suggested a potential nosocomial transmision of C. albicans since the same DTS clones were found in different wards. Amplification of specific H. pylori gene (ureA) was applied to find a presence of this bacteria in Candida cells. Positivity was detected in 15.27% of Candida spp. (C. albicans, C. tropicalis, C. orthopsilosis) isolated from oral mucosa, sputum, vagina, and gastric fluid.