Isolation and biotyping of candida species in high risk pediatric groups and in women with vaginitis, comparative studies on methodology

One hundred cases were divided into 4 groups which included 50 neonates and infants having oral thrush [Group I], 15 leukaemic children [Group II], 15 women suffering from vaginitis [Group III] and 20 control cases, apparently healthy children and women [Group IV]. Oral, rectal and vaginal swabs collected from the mentioned cases, were examined mycologically for the presence of different candida species. We used the ordinary conventional methods [Morphology, culture, fermentation and assimilation tests]. A randomly selected 30 strains were further biotyped by the rapid Candifast method and by the updated automated Vitek Yeast Biochemical Card System considering the ordinary conventional methods as the standard. Candida [C.] species were isolated from 68% and 40% of oral and rectal samples of Group I, 73.3% and 46.7% of oral and rectal samples of Group II and 66.7% and 13.3% of vaginal and oral samples of Group III compared with 10% from oral and vaginal samples of the control group. C. albicans was the predominant type among the yeast isolated in this study. No biotypic variation among C. species isolated from the different samples. Evaluation of the results of both conventional and Candifast methods revealed 100% agreement in identification of C. albicans, C. pseudotropicalis, C. glabrata and C. guilliermondii but there was little disagreement as regards C. stellatoidea [20%], C. tropicalis [25%], C. Krusei [33.3%] and C. parapsilosis [33.3%]. As regard the Vitek YBC System, there was an agreement [100%] between its results and the conventional methods in identification of all Candida strains except two strains only which showed little disagreement, C. stellatoidea [20%] and C. krusei [33.3%]. The automated Vitek YBC System is rapid, updated and accurate but it is expensive and lacks the performance of antifungal sensitivity testing which could be done by the Candifast method for the randomly selected 30 Candida strains