A research team collected 3,806 reproductive tract secretion samples from pregnant women with vaginal discomfort at Haikou Maternal and Child Health Hospital between May 2021 and August 2023. Microscopic examinations showed that all samples contained yeast or yeast-like cells, consistent with vulvovaginal candidiasis (VVC).
From these samples, 594 yeast isolates were obtained, with an overall isolation rate of 15.6%. Among them, Candida glabrata accounted for 36.2% (215 isolates), second only to Candida albicans which made up 45.1% (267 isolates).
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Antifungal susceptibility testing was a key part of the study, which is published in Mycology. The team tested the isolates’ susceptibilities to four commonly used clinical antifungal drugs: fluconazole, itraconazole, voriconazole, and amphotericin B. Strikingly, 64.5% of the 594 yeast isolates (383 isolates) showed resistance (R) or intermediate (I) phenotypes to at least one of these drugs. Among the 215 C. glabrata isolates, 81.4% were intermediate or resistant to at least one antifungal, and 10% were resistant to multiple agents.
Genetic diversity
To explore the genetic diversity of C. glabrata, the researchers conducted multilocus sequence typing (MLST) on 122 strains. These strains included 52 from the reproductive tracts of pregnant women, 53 from the oral cavities of asymptomatic patients, and 17 from environmental sources in Hainan.
The analysis revealed 14 sequence types (STs). Six of these STs were shared among at least two of the three ecological niches, indicating a certain degree of genetic connection. Nine of the STs had been previously reported, while five were newly discovered in this study. The most prevalent genotype was ST7 (32.0%), followed by ST19 (26.2%). Different ecological niches had distinct dominant STs; for example, ST19 was the most common in the genital tract of pregnant women.
The team also compared the Hainan C. glabrata MLST data with the globally published MLST data. Phylogenetic analysis showed that the 14 STs from Hainan were widely distributed on the phylogenetic tree, suggesting diverse origins. Hainan shared the most prevalent genotype, ST7, with mainland China and Japan, but differed from countries like the United States, Australia, Denmark, and the United Kingdom. Five unique genotypes were found only in Hainan.
Global spread
Prof. Jianping Xu said, “Our study provides a comprehensive understanding of C. glabrata in the reproductive tracts of pregnant women in Hainan. The high prevalence of non - albicans Candida species, especially C. glabrata, and its high-level drug resistance highlight the need for updated treatment strategies. The genetic diversity insights can also contribute to better understanding the global spread and evolution of this pathogen.”
The current understanding of C. glabrata in pregnant women’s reproductive tracts in Hainan has been limited. This study fills this knowledge gap and provides new evidence for clinical treatment and further research on the epidemiology and evolution of C. glabrata. It also paves the way for future studies to explore the sources of drug-resistant strains and the impact of genetic diversity on treatment outcomes.
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