Insights and advances in recurrent vulvovaginal candidiasis

Vaginal colonization and vertical transmission of Candida species: prevalence and associated factors among pregnant women and their neonates at public health facilities of Northeast Ethiopia

BACKGROUND

Vaginal colonization by Candida can lead to vulvovaginal candidiasis, which is the second most prevalent vaginal condition globally. It is frequently associated with sepsis and adverse neonatal outcomes in pregnant women. This issue is worsening in Sub-Saharan Africa, including Ethiopia. However, evidence of the existing problem is very scarce yet crucial. Thus, this study aimed to determine the vaginal colonization and vertical transmission of Candida species and their associated factors among pregnant women and their neonates in public health facilities of northeast Ethiopia.

METHODS

A facility-based cross-sectional study was conducted at selected public health facilities in Dessie town from April 1 to June 30, 2023, among 348 pregnant women and their newborns, using convenience sampling techniques. Socio-demographic, and clinical-related data were collected using a pre-tested, semi-structured questionnaire. Vaginal swab samples from pregnant women and pooled swabs from the external ear, nasal area, and umbilical areas of the newborns were collected and transported using Amies transport media. The samples were inoculated into Sabouraud Dextrose Agar for isolation, followed by inoculation onto a standard CHROM agar Candida plate for species identification, and a germ-tube test confirmed pseudophyphae of C.albicans. Data was entered into Epi Data version 4.6.0 software and exported and analyzed by SPSS version 25.0. A stepwise logistic regression model was used to identify the associated factors. Variables with p < 0.05 and their 95% confidence interval were considered statistically significant.

RESULT

A total of 348 pregnant women attending vaginal delivery were included in the study. The maternal and neonatal colonization rates of Candida species were 14.1% (49/348) and 6.3% (22/348), respectively. The overall proportion of vertical transmission of Candida species was 44.9% (22/49, 95% CI: 41.2, 49.7). Among Candida isolates, 63.3% (31/49) were C. albicans and 36.7% (18/49) were C. krusei. Gestational diabetes mellitus (AOR: 4.2, 95% CI: 1.23-38.6, P = 0.047) and HIV (AOR: 1.58, 95% CI: 1.11-6.12, P = 0.049) were independently associated with maternal colonization of Candida species. Moreover, rural residence (AOR = 3.6, 95% CI: 1.37-9.5, P = 0.010) and maternal age above 28 years (AOR = 2.39, 95% CI: 1.97-5.89, P = 0.048) were independently associated with vertical transmission of Candida species.

CONCLUSION

The findings of this study highlight the need for effective screening and treatment of Candida colonization during antenatal care.

Constraint on boric acid resistance and tolerance evolvability in Candida albicans

Boric acid is a broad-spectrum antimicrobial used to treat vulvovaginal candidiasis when patients relapse on the primary azole drug fluconazole. Candida albicans is the most common cause of vulvovaginal candidiasis, colloquially referred to as a "vaginal yeast infection". Little is known about the propensity of C. albicans to develop BA resistance or tolerance (the ability of a subpopulation to grow slowly in high levels of drug). We evolved 96 replicates from eight diverse C. albicans strains to increasing BA concentrations to test the evolvability of BA resistance and tolerance. Replicate growth was individually assessed daily, with replicates passaged when they had reached an optical density consistent with exponential growth. Many replicates went extinct quickly. Although some replicates could grow in much higher levels of BA than the ancestral strains, evolved populations isolated from the highest terminal BA levels (after 11 weeks of passages) surprisingly showed only modest growth improvements and only at low levels of BA. No large increases in resistance or tolerance were observed in the evolved replicates. Overall, our findings illustrate that there may be evolutionary constraints limiting the emergence of BA resistance and tolerance, which could explain why it remains an effective treatment for recurrent yeast infections.

Patients with recurrent vulvovaginal candidiasis exhibit a decrease in both the fungicidal activity of neutrophils and the proliferation of peripheral blood mononuclear cells

BACKGROUND

Recurrent vulvovaginal candidiasis (RVVC) is an important and underestimated fungal infection.

OBJECTIVE

We aimed to determine the fungicidal and proliferative capacities of neutrophils and peripheral blood mononuclear cells (PBMCs), respectively and the clinical and microbiological characteristics of a cohort of Colombian patients diagnosed with RVVC.

METHODS

A cross-sectional study was conducted. A total of 66 women were included (40 diagnosed with RVVC and 26 healthy women [HW]). Demographic and clinical data were recorded. Vaginal fluid samples were obtained for isolation, identification and antifungal susceptibility testing of Candida species using selective culture media and the Vitek 2.0® system. Blood samples were also obtained to evaluate cell subpopulations; furthermore, neutrophils and PBMCs were isolated to determine their fungicidal and proliferative capacities, respectively.

RESULTS

The median age was 29 (IQR: 34-23) for RVVC and 24 (IQR: 30-23) for HW. Only two species of the genus Candida were identified: Candida albicans (92.5%) and Candida lusitaniae (7.5%). Resistance to fluconazole, voriconazole, flucytosine and amphotericin B was observed on six C. albicans isolates and one C. lusitaniae isolate. Only the family history of vulvovaginal candidiasis was associated with RVVC occurrence. The RVVC group exhibited a significantly higher number of neutrophils but with lower fungicidal activity in comparison to HW; likewise, PBMCs from RVVC patients presented a lower proliferation index when stimulated with C. albicans.

CONCLUSION

Contrary to what has been reported worldwide, in Colombian patients with RVVC, C. albicans was the main isolated species without increased antifungal resistance. The diminished fungicidal and proliferative capacities of neutrophils and PBMCs, respectively, could suggest a possible alteration in the innate and adaptive immune responses.