Study site and population

This study was carried out from April to June 2022 at the microbiology laboratory of the Military Hospital of Ouakam. The study population included women referred to the laboratory for vaginal discharge during the study period. The Military Hospital of Ouakam is a level 3 public hospital located in Dakar, the capital city of Senegal.

Sample and data collection

From each patient, two vaginal swabs (VS) and socio-demographic parameters such as age, symptoms, marital status, education level, and address were collected. One VS was used to perform a wet smear and a thin smear for Gram Stain. The second VS was used for inoculation of Sabouraud Dextrose Agar (SDA). The culture medium was incubated at 35 to 37°C during 18 to 24 h under aerobic conditions. Plates without growth after 24 h were re-incubated for a further 24 h. Preparation and performance evaluation of the culture media was performed according to the manufacturer's instructions.

Identification and antifungal susceptibility of Candida species

Species identification and antifungal susceptibility testing of yeasts were determined by the automated Vitek^® 2 compact system (bioMe?rieux, France) using YST-21343 and AST-YS01 cards. The VITEK 2 compact is a computerized microbiology system using growth-based technology using colorimetric reagent cards that are automatically incubated and interpreted. The YST-21343 identification card is based on established biochemical methods and newly developed substrates. The AST-YS07 Vitek^® 2 Antifungal Susceptibility Card is intended for use with Vitek^® 2 systems in clinical laboratories as an in vitro test to determine the susceptibility of Candida. Briefly, isolated yeast colonies were selected on Sabouraud agar, then transferred aseptically 3.0 ml of sterile saline (0.45 to 0.50% aqueous NaCl, pH 4.5 to 7.0) into a clear plastic test tube (12 mm × 75 mm). Next, a sterile swab transfers a sufficient number of morphologically similar colonies into the saline tube. A homogeneous suspension of organisms with a density equivalent to a McFarland No. 1.80 to 2.20 using the Vitek^® 2 DensiCHEKTM Plus was prepared. Finally, the suspension tube and the YST card were placed into the cassette. The filled cassette was inserted manually into Vitek^® 2 compact reader-incubator module. The final identification of excellent, good, acceptable, or low discrimination was considered correct.

Statistical analysis

Statistical analyses were performed using R software. Continuous variables were described as mean (standard deviation). Normally distributed variables were compared with a t-test. Categorical variables were presented as percent, and Fisher exact or Chi-squared tests were used for proportional assessments. Univariate logistic regression analysis assessed the association between the related risk factors and positivity. Four age groups were defined for analysis, that is, 17 to 25 years; 26 to 35 years; 36 to 45 years, and over 45 years. For all statistical tests, we accepted that a two-sided level of significance was set at p≤ 0.05.

Ethical considerations

This study was hospital-based research conducted in normal conditions under the Declaration of Helsinki. Ethical permission was obtained from the hospital authorities, and the patient's consent was also received before specimen collection. Information collected during the study was analyzed using the participant's identification code to ensure confidentiality. 

Antifungal susceptibility

Antifungal susceptibility was tested for six drugs: Amphotericin B (AMB), Flucytosine (FCT), Fluconazole (FLU), Caspofungin (CAS), Micafungin (MCF), and Voriconazole (VRC)). From the 38 Candida strains isolated, 34 antifungal susceptibilities were successfully performed as follows: C. albicans (n=24), C. glabrata (n =7), C. tropicalis (n=2), and C. kefyr (n=1). C. albicans strains showed 100% susceptibility regarding the different antifungals except for Flucytosine, in which two cases of resistance (8.34%) were noted. The observed susceptibility rates of C. glabrata to FLU, VRC, CAS, MCF, AMB, and FCT were 0, 100, 14.29, 100, 100, and 100%. C. tropicalis antifungal susceptibility was 100% for all tested drugs, while C. kefyr susceptibility was only noted for Voriconazole and Flucytosine (Figure 1).

(2012) but in contradiction with the results of Yadav and Prakash (2016) and Bitew and Abebaw (2018), who reported that illiterate women were more affected than those patients with primary school education and above. These findings suggest that the hypothesis that improved personal hygiene resulting from schooling can reduce the risk of vaginal infection may not always be verified. According to marital status, singles were more affected than married patients in our study, but the association was not statistically significant. The same trend was previously observed by Sylla (2018) in Dakar. Similarly, in Ethiopia, Bitew and Abebaw (2018) reported that vulvovaginal candidiasis was higher among divorced study subjects (52.6%) compared to unmarried (41.5%) or married (37.4%) study subjects. Contrary to the report of Waikhom et al. (2020) in Accra, most of the VVC were noted as married subjects.

Prevalence of different isolated Candida spp.

In this report, cultures were positive for 38 strains (31.93%), with four Candida species identified: C. albicans (72%), C. glabrata (19%), C. tropicalis (6%) and C. kefyr (3%). The most frequently isolated species was C. albicans. The non-albicans species (NAS) were observed in 28%. These findings align with those reported by Sylla (2018) who estimated the prevalence of C. albicans at 71.51% and that of NAS at 27.96%. Also, the predominance of C. albicans was noted in the series of Shi et al. (2020) 76.9% and in Ethiopia by Bitew and Abebaw (2018) at 58.6%. However, in Accra, C. glabrata was identified as the main species causing vulvovaginal candidiasis with 57.4% (Waikhom et al., 2020), while this species ranked in the second position in our series with 19%. In Ivory Coast (Kpongbo et al., 2018) and Iran (Rezaei-Matehkolaei et al., 2016), C. glabrata ranks second in species causing vaginal candidiasis with 19.2 and 8.8%, respectively. In Ethiopia, Bitew and Abebaw (2018) reported that C. krusei was the most isolated species after C. albicans in vaginal candidiasis. Regarding the frequency of C. tropicalis (6%) and C. kefyr (3%), our results are in line with those found in Iran and Vietnam by Anh et al. (2021) and Nejat et al. (2018) who reported a prevalence of 4.31 and 5.7%, respectively.

Antifungal susceptibility

In our study, antifungal susceptibility was assessed for Fluconazole, Voriconazole, Caspofungin, Micafungin, Amphotericin B, and Flucytosine.

Regarding the Azoles antifungal group (Fluconazole and Voriconazole), all isolated Candida strains were 100% susceptible to Voriconazole. C. kefyr and C. glabrata were not tested with Fluconazole. On the other hand, no resistance  to  Fluconazole  was  found  for  C. albicans and C. kefyr strains, that is, 100% susceptibility

of both species to Fluconazole. The same trend of antifungal susceptibility of azoles was reported by Bitew and Abebaw (2018). However, Sharifynia et al. (2017) suggested a high resistance of C. albicans to Fluconazole than in non-albicans Candida spp.

The antifungal susceptibility test to the Echinocandins group (Caspofungin and Micafungin) showed 100% susceptibility of all isolated Candida spp., except C. glabrata which showed 28.57% of resistance to Caspofungin and 53.14% susceptible dose-dependent (intermediate) to the same drug. Regarding Micafungin, our results are supported by Anh et al. (2021) and Bitew and Abebaw (2018) who reported 100% susceptibility of 133 Candida spp. involved in VVC to Micafungin. However, regarding Caspofungin susceptibility, a resistance rate of 4.7% was reported for C. albicans by Rezaei-Matehkolaei et al. (2016).

Regarding Amphotericin B and Flucytosine susceptibility tests, all isolated Candida strains were 100% susceptible to amphotericin B. This finding agrees with Abidjan's findings by Kpongbo et al. (2018) who showed that all Candida strains isolated in his series were susceptible to amphotericin B.

Also, in our series, all Candida spp. were sensitive to Flucytosine, except for two C. albicans strains suggesting a resistance of 8.34%. Previously in Senegal, Mane et al. (unpublished data) reported a resistance rate of C. albicans to flucytosine of 4%. Similarly, a low resistance rate of 2% of C. albicans to Flucytosine was found by Bitew and Abebaw (2018). 

This study regarding the frequency of species involved in vulvovaginal candidiasis and their antifungal susceptibility in Dakar reveals a prevalence rate comparable with those previously reported in Dakar. Furthermore, it overviews the distribution of Candida spp. in Dakar. Concerning the antifungal susceptibility, C. albicans, the main species involved in VVC, showed a high susceptibility rate to the different antifungals tested. However, antifungal susceptibility monitoring for early resistance detection should be continued.

The authors have not declared any conflict of interests.

The authors are grateful to the patients who participated in this study. They thank all the microbiology laboratory staff who participated in this study.