Distribution, antifungal susceptibility pattern and intra-Candida albicans species complex prevalence of Candida africana: A systematic review and meta-analysis

Reported prevalence and comparison of diagnostic approaches for Candida africana: a systematic review with meta-analysis

This systematic review and meta-analysis evaluated reported prevalence and diagnostic methods for identifying Candida africana, an opportunistic yeast associated with vaginal and oral candidiasis. A comprehensive literature search yielded 53 studies meeting the inclusion criteria, 2 of which were case studies. The pooled prevalence of C. africana among 20,571 participants was 0.9% (95% CI: 0.7-1.3%), with significant heterogeneity observed (I2 = 79%, p < 0.01). Subgroup analyses revealed regional variations, with North America showing the highest prevalence (4.6%, 95% CI: 1.8-11.2%). The majority 84.52% of the C. africana have been isolated from vaginal samples, 8.37% from oral samples, 3.77% from urine, 2.09% from glans penis swabs, and 0.42% from rectal swabs, nasal swabs, and respiratory tract expectorations respectively. No C. africana has been isolated from nail samples. Hyphal wall protein 1 gene PCR was the most used diagnostic method for identifying C. africana. It has been used to identify 70% of the isolates. A comparison of methods revealed that the Vitek-2 system consistently failed to differentiate C. africana from Candida albicans, whereas MALDI-TOF misidentified several isolates compared with HWP1 PCR. Factors beyond diagnostic methodology may influence C. africana detection rates. We highlight the importance of adapting molecular methods for resource-limited settings or developing equally accurate but more accessible alternatives for the identification and differentiation of highly similar and cryptic Candida species such as C. africana.

Lack of Candida africana in Ugandan pregnant women: results from a pilot study using MALDI-ToF

BACKGROUND

Candida africana is an emergent variant that has been listed as a new species or variety within the Candida albicans complex since 2001. It has a worldwide intra-albicans complex pooled prevalence of 1.67% and varies between 0 and 8% depending on geographical region. We present the results of a pilot study on its prevalence in Uganda.

METHODOLOGY

We conducted a cross-sectional study between March and June 2023. We recruited 4 pregnant women from Mulago Specialized Women and Neonatal Hospital, 102 from Kawempe National Referral Hospital, and 48 from Sebbi Hospital. Vaginal swabs were tested using microscopy, culture and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF).

RESULTS

The prevalence of C. africana was zero. Out of the 103 isolates, the majority (81.553%) were identified as Candida albicans, followed by Nakeseomyces glabrata (13.592%) and Pichia kudriavzevii (1.942%). Cyberlindnera jadinii, Candida tropicalis, and Candida parapsilosis each accounted for 0.971% of the isolates.

CONCLUSION

The prevalence of C. africana in Uganda is zero. However, large-scale cross-sectional studies, including studies involving the collection of vaginal samples from both urban and rural settings in Uganda and the use of both MALDI-TOF- and PCR-based laboratory methods, are needed to fully describe the public health burden of C. africana infections.

Molecular epidemiology of Candida africana isolates collected from vagina swabs in French Guiana

Previous molecular studies have shown that Candida africana corresponds to the clade 13 of Candia albicans. It has been mostly involved in vulvovaginal candidiasis worldwide but few data exist in South America. The aim of our study was to investigate the prevalence of C. africana in women living in French Guiana. For this, we first set up a fluorescent-intercalating-dye-real time Polymerase Chain Reaction (PCR) targeting the hyphal wall protein 1 gene. The test was applied to 212 C. albicans isolates collected from May to August 2019 from vaginal swabs, allowing the identification of six women harboring C. africana (eight isolates). The in vitro susceptibility of these eight isolates to six antifungal drugs was also evaluated. No demographics or clinical-specific features could be demonstrated. Genetic diversity of those isolates was analyzed through multilocus sequence typing and showed that diploid sequence type 182 was predominant (n = 6) and allowed the report of a new diploid sequence type.

The pathogenic and colonization potential of Candida africana

The Candida albicans population displays high genetic diversity illustrated by 18-well differentiated genetic clusters. Cluster 13, also known as Candida africana, is an outlying cluster and includes strains first described as atypical C. albicans isolates of vaginal origin, showing apparent tropism for the female genital tract. In our study, we combined in vitro, and in vivo models to explore the colonization and pathogenic potential of C. africana. We report that C. africana has similar fitness to C. albicans when it comes to colonization of the oral and vaginal mucosa, however it has decreased fitness in gastro-intestinal colonization and systemic infection. Interestingly, despite high population homogeneity, our in vitro data highlighted for the first time a variability in terms of growth rate, biofilm formation and filamentation properties between C. africana strains. Overall, our data lays the foundations for exploring specific features of C. africana that might contribute to its apparent niche restriction.

Species identification, antifungal susceptibility patterns, and vitamin D3 level in women with vaginal candidiasis: a case-control study in Iran

Vulvovaginal candidiasis (VVC) is a fungal infection that is a global issue of women's health due to its association with morbidity, infertility, and economic costs. This study aimed to compare the vitamin D3 levels between women with VVC to healthy controls and determine the species distribution and susceptibility pattern of isolates. Species identification was performed using sequencing of the ITS-rDNA regions and amplification of the HWP1 gene. Antifungal susceptibility testing was determined by the disk diffusion method. Moreover, serum vitamin D3 levels were measured using a commercial ELISA (enzyme-linked immunosorbent assay) kit. Our results indicated that vitamin D3 level in women with VVC was lower than those of healthy women (p-value < .001). Candida albicans complex (62.8 percent) was the most common species, and most species were susceptible to fluconazole, itraconazole, ketoconazole, and nystatin. In conclusion, our study revealed a potential link between vitamin D3 deficiency and VVC in women. Although our findings showed significantly lower vitamin D3 levels in women with VVC, further research is needed to establish a definitive causative relationship between vitamin D3 deficiency and VVC. Nonetheless, our study highlights the potential importance of maintaining adequate levels of vitamin D3 and the need for further exploration in this area.

Prevalence of Closely Related Candida albicans Species among Patients with Vulvovaginal Candidiasis in Southern Poland Based on the hwp1 Gene Amplification

Candida albicans remains the most common species isolated from women with vulvovaginal candidiasis. However, closely related species such as Candida africana and Candida dubliniensis may also occur, although they are often misidentified. The aim of the study was to confirm the phenotypic identification of C. albicans and its closely related species isolated from women with genital tract infections by amplification of the hwp1 (hyphal wall protein 1) gene in a PCR assay. We report a detailed molecular identification of C. albicans and its closely related species among 326 patients in the Małopolska region, Poland. Initial phenotypic identifications were confirmed by amplification of the hwp1 gene. Based on molecular analysis, we revealed 307 strains (94.17%) as C. albicans and 17 as C. dubliniensis (5.22%). No strain of C. africana was detected. Two patients h ad co-infection with C. albicans and C. dubliniensis (0.61%). A PCR assay targeting the hwp1 gene was reliable for correctly identifying species among the C. albicans complex.

Vulvovaginal candidiasis in Iranian women: Molecular identification and antifungal susceptibility pattern

AIM

Vulvovaginal candidiasis (VVC), is a common fungal infection that remains a global concern. The objectives of this study were molecular identification and assessment of the antifungal susceptibility profile of Candida species, causing VVC in southeast Iran.

METHODS

A cross-sectional investigation was carried out on 119 nonpregnant females suspected of VVC between February 2019 and May 2021. Yeast samples were characterized to the species level by conventional and molecular methods. All Candida isolates were examined for in vitro susceptibility profile to six conventional antifungal drugs using Clinical and Laboratory Standards Institute guidelines.

RESULTS

Out of 119 subjects, 52 (43.7%) cases were affected by VVC, out of whom 11 (21.15%) cases had recurrent vulvovaginal candidiasis (RVVC). The species distribution was as follows; Candida albicans (n = 21; 40.4%), C. glabrata (n = 11; 21.2%), C. tropicalis (n = 9; 17.3%), C. parapsilosis (n = 5; 9.7%), C. africana (n = 3; 5.7%), C. famata (n = 1; 1.9%), C. lusitaniae (n = 1; 1.9%), and C. dubliniensis (n = 1; 1.9%). The resistance rate of Candida isolates to fluconazole, itraconazole, and voriconazole were 15.38%, 11.5%, and 3.8%, respectively. Resistance to fluconazole was obtained in 46% (5/11) of RVVC cases but only in 7% (3/41) of VVC cases.

CONCLUSION

This study demonstrated that the majority of VVC cases were caused by non-albicans Candida species which also were resistant to some antifungal agents. Hence, our findings revealed the importance of conducting periodical epidemiological studies to determine changes in species distribution. Moreover, for effective management of treatment and infection, it is imperative to evaluate the susceptibility profiles of Candida species isolated from VVC patients.

Overview on the Infections Related to Rare Candida Species

Atypical Candida spp. infections are rising, mostly due to the increasing numbers of immunocompromised patients. The most common Candida spp. is still Candida albicans; however, in the last decades, there has been an increase in non-Candida albicans Candida species infections (e.g., Candida glabrata, Candida parapsilosis, and Candida tropicalis). Furthermore, in the last 10 years, the reports on uncommon yeasts, such as Candida lusitaniae, Candida intermedia, or Candida norvegensis, have also worryingly increased. This review summarizes the information, mostly related to the last decade, regarding the infections, diagnosis, treatment, and resistance of these uncommon Candida species. In general, there has been an increase in the number of articles associated with the incidence of these species. Additionally, in several cases, there was a suggestive antifungal resistance, particularly with azoles, which is troublesome for therapeutic success.

Vulvovaginal candidiasis: An overview of mycological, clinical, and immunological aspects

AIM

To provide an overview of clinical, immunological, and mycological aspects of vulvovaginal candidiasis (VVC).

METHODS

A literature search was conducted to find relevant articles about different aspects of VVC. Related data from retrieved articles were summarized in different headings.

RESULTS

VVC has a global distribution and Candida albicans is the leading cause of infection except for specific patient groups like postmenopausal, diabetic, or immunocompromised women. VVC has a range of clinical presentations, accordingly, its diagnosis should be based on clinical examination coupled with laboratory investigations. The best therapeutic regimen depends on the patient's conditions and the causative agent. Moreover, factors like drug resistance of the causative agents and different mutations in the immunity-related genes could affect the treatment outcome.

CONCLUSION

As a globally distributed disease, VVC needs further attention, especially in areas related to the treatment failure and recurrence of the disease.

Differentiation of Candida albicans complex species isolated from invasive and non-invasive infections using HWP1 gene size polymorphism

Background and Purpose

Taxonomy of Candida is controversial and has changed due to the investigation of the novel species. Candida africana and Candida dubliniensis are new members of the C. albicans complex that are currently gaining both clinical and epidemiologic significance. This study aimed to report the prevalence of C. africana among the strains isolated from patients using hyphal wall protein 1 (HWP1) gene size polymorphism.

Materials and Methods

In total, 235 yeasts confirmed as C. albicans complex based on chromogenic media and internal transcribed spacers sequencing isolated from various clinical forms of invasive and non-invasive candidiasis mainly candidemia were re-identified using HWP1 gene polymorphisms. The HWP1-polymerase chain reaction amplicons were re-confirmed by sequencing and BLAST analysis.

Results

Based on the HWP1 gene size polymorphism, 223 strains were identified as C. albicans (94.89%) from which 7 isolates produced two DNA fragments (850 and 941 bp). The C. dubliniensis (n=4, 1.7%), C. africana (n=1, 0.42%), and mix of C. albicans and C. africana (n=7, 2.97%) were also identified.

Conclusion

It can be said that C. albicans remains the most common Candida species, while C. dubliniensis and C. africana are rarely found among the patient isolates. Due to limited information on the molecular epidemiology of this novel yeast, more studies using molecular methods are recommended.

Molecular identification and antifungal susceptibility profiles of Candida dubliniensis and Candida africana isolated from vulvovaginal candidiasis: A single-centre experience in Iran

Background

Vulvovaginal candidiasis (VVC) is a common and debilitating long‐term illness affecting million women worldwide. This disease is caused mainly by Candida albicans and a lesser extent by other species, including the two phylogenetically closely related pathogens Candida africana and Candida dubliniensis.

Objectives

In this study, we report detailed molecular epidemiological data about the occurrence of these two pathogenic yeasts in Iranian patients affected by VVC, or its chronic recurrent form (RVVC), and provide, for the first time, data on the antifungal activity of two new drugs, efinaconazole (EFN) and luliconazole (LUL).

Methods

A total of 133 vaginal yeast isolates, presumptively identified as Calbicans by phenotypic and restriction analysis of rDNA, were further analysed by using a specific molecular method targeting the HWP1 gene. All Cafricana and Cdubliniensis isolates were also tested for their in vitro susceptibility to a panel of modern and classical antifungal drugs.

Results and Conclusions

Based on the molecular results, among 133 germ‐tube positive isolates, we identify 119 Calbicans (89.47%), 11 Cafricana (8.27%) and 3 Cdubliniensis (2.26%) isolates. Cafricana and Cdubliniensis showed low MIC values for most of the antifungal drugs tested, especially for EFN and LUL, which exhibited a remarkable antifungal activity. High MIC values were observed only for nystatin and terbinafine. Although Calbicans remains the most common Candida species recovered from Iranian VVC/RVVC patients, our data show that its prevalence may be slightly overestimated due to the presence of difficult‐to‐identify closely related yeast, especially Cafricana.

Candida africana and Candida dubliniensis as causes of pediatric candiduria: A study using HWP1 gene size polymorphism

Background

Candida species cause a wide spectrum of disease entities. Candida africana and Candida dubliniensis-members of Candida albicans complex-are currently gaining both clinical and epidemiologic significance.

Materials and methods

Totally, 150 pediatric isolates that had previously been identified as C. albicans species complex based on a positive germ tube test were included. The isolates were cultured on CHROMagar Candida medium to ensure their purity and the results of germ tube test. For definitive speciation, PCR amplification and size polymorphism of the hyphal wall protein 1 (HWP1) gene was used. The results of HWP1-PCR were confirmed by sequencing the amplified fragments for randomly selected isolates of C. africana and C. dubliniensis.

Results

All 150 isolates included in this study were reconfirmed as C. albicans complex on chromogenic media. Based on the HWP1 gene size polymorphism, 141 (94%) isolates were identified as C. albicans, 2 (1.33%) as C. africana, and 1 (0.67%) as C. dubliniensis. The remaining 6 (4%) C. albicans complex isolates were a mix of C. albicans and C. africana. All isolates of C. africana and C. dubliniensis have been recovered from cases of candiduria.

Conclusion

C. africana, either alone or mixed with C. albicans, could be a cause of candiduria among pediatric patients and should not be ignored.