Abstract
BackgroundCandida tropicalis (C. tropicalis) is an important opportunistic pathogenic Candida species that can cause nosocomial infection. In this study, we analyzed the distribution and drug susceptibility of C. tropicalis and the relationship between ERG11 and UPC2 expression and resistance to azole antifungal agents.MethodsC. tropicalis was cultured and identified by Sabouraud Agar Medium, CHROM Agar Candida and ATB tests (Bio-Mérieux, France). Total RNA was extracted from the collected strains, and the ERG11 and UPC2 mRNA expression levels were analyzed by quantitative real-time PCR.ResultsIn total, 2872 clinical isolates of Candida, including 319 strains of C. tropicalis, were analyzed herein; they were mainly obtained from the Departments of Respiratory Medicine and ICU. The strains were predominantly isolated from airway secretion samples, and the detection trend in four years was mainly related to the type of department and specimens. The resistance rates of C. tropicalis to fluconazole, itraconazole and voriconazole had been increasing year by year. The mRNA expression levels of ERG11 and UPC2 in the fluconazole-resistant group were significantly higher than they were in the susceptible group. In addition, there was a significant positive linear correlation between these two genes in the fluconazole-resistant group.ConclusionsOverexpression of the ERG11 and UPC2 genes in C. tropicalis could increase resistance to azole antifungal drugs. The routine testing for ERG11 and UPC2 in high-risk patients in key departments would provide a theoretical basis for the rational application of azole antifungal drugs.
Highlights
Candida tropicalis (C. tropicalis) is widely distributed in nature and is a common colonizer of the human skin, oral cavity and digestive tract [1]
Our results showed statistical significance only for C. albicans (χ2 = 12.620; P = 0.006) and C. tropicalis (χ2 = 20.410; P < 0.001) (Additional file 1: Fig. S1)
Our results showed that the relative mRNA expression levels of ERG11 and UPC2 genes in C. tropicalis from the fluconazole-resistant group (27/30 strains fully resistant to fluconazole, itraconazole, and voriconazole) and fluconazole- susceptible group were normally distributed
Summary
Candida tropicalis (C. tropicalis) is widely distributed in nature and is a common colonizer of the human skin, oral cavity and digestive tract [1]. C. tropicalis is an important opportunistic pathogenic Candida species that can cause nosocomial infection, and its isolation rate is second to that of Candida albicans (C. albicans) [2]. The global SENTRY antifungal surveillance report in 2013 showed that the resistance rate of C. tropicalis to fluconazole was 11.60% (in 31 countries total) [7]. Data from the China Invasive Fungal Resistance Monitoring Network (CHIF-NET) had shown that the resistance rate of C. tropicalis to fluconazole increased from 11.20% in 2009 to 42.70% in 2014 [8]. The risk factors involved in C. tropicalis infection, the. Candida tropicalis (C. tropicalis) is an important opportunistic pathogenic Candida species that can cause nosocomial infection. We analyzed the distribution and drug susceptibility of C. tropicalis and the relationship between ERG11 and UPC2 expression and resistance to azole antifungal agents
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