Characterization Of Fungal Species In Vulvovaginal Candidiasis And Establishment Of Rapid Identification Method

Part I Identification and characterization of pathogenic fungi in vulvovaginalcandidiasisObjective To characterize distribution of fungal species in vulvovaginalcandidiasis through biological classification and gene identification of clinicalpathogenic isolates. To analyze the distribution of pathogenic isolates invulvovaginal candidiasis and characteristics of the disease.Methods Vaginal secretion samples from patients with vulvovaginalcandidiasis were collected from July2012to January2013. Patients with bothtypical symptom and positive finding of hyphae or spores under microscopywere allocated into vulvovaginal candidiasis (VVC) group. Patients withrecurrence of four times a year and above were allocated into recurrentvulvovaginal candidiasis (RVVC) group. Patients with positive fungalexamination but no clinical symptoms were allocated into carrier (H) group.DNA was extracted from colonies on SDA medium. ITS1-2region wasamplified with ITS1and ITS2primers by PCR. The PCR products were sentfor gene sequencing and the results were blasted on genbank to determine thespecies.Results Altogether151clinical samples with positive microscopic finding werecollected. Among the samples,112isolates grew on culture medium, and104isolates were identified by gene sequencing. Finally,90isolates of Candida albicans (86.54%),13isolates of Candida glabrata (12.5%) and1isolate ofAlternaria (0.96%) were identified. The proportion of Candida albicans inVVC group, RVVC group and H group is90.48%,86.21%and50%respevtively, suggesting Candida albicans belong to resident microflora inhuman vagina. The ratio of Candida glabrata in VVC group, RVVC group andH group is4.76%,10.38%and25%respevtively, suggesting the pathogenicityof Candida glabrata is moderate than that of Candida albicans. Most of thetime, Candida glabrata reside in human vagina without causing any symptoms.Candida albicans and Candida glabrata could both be found in healthy carriers.Among patients between25and30, the infection rate of Candida albicans isthe highest.Conclusion PCR is rapid and accurate diagnostic method for clinicalpathogenic fungi, in general. Candida albicans are most common pathogencausing vulvovaginal candidiasis. Among non-Candida albicans, Candidaglabrata is common pathogen. Both Candida albicans and Candida glabratacould be isolated from healthy carriers. In patients with sexually active age, theinfective rate of Candida albicans is highest.Part II Rapid identification of pathogenic fungi in patients with vulvovaginalcandidiasisObjective To identify pathogenic fungi rapidly through vaginal secretionsamples from patients with vulvovaginal candidiasis.Methods Vaginal secretion samples from patients with vulvovaginal candidiasis were collected. Then the fungal DNA was extracted from thesecretion samples directly. ITS1-2region was amplified and the PCR productswere sent for sequencing. The isolates were identified by blasting. Finally, thediagnostic results from vaginal secretion samples and culture colonies werecompared.Results The efficiency of extracting DNA from vaginal samples and culturecolonies are both95.24%. No significant difference was detected. For PCRproducts from vaginal samples, the effective rate of sequencing is95.24%,while for that from the colonies, the effective rate is61.9%. Besides, thesequencing results of two methods do not match completely.Conclusion Pathogenic fungi could be identified through vaginal secretionsamples from patients with vulvovaginal candidiasis rapidly and accurately,which is better than the traditional diagnostic methods.