Synergistic interaction of fluconazole/sodium bicarbonate on the inhibition of Candida glabrata phospholipase gene

Abstract Candida glabrata infections are responsible for deaths of people globally. Fluconazole is known to be less effective against C. glabrata, which developed many strategies to evade being destroyed by fluconazole. To achieve enhanced efficacy of fluconazole against C. glabrata, the interaction of fluconazole with sodium bicarbonate was investigated using the CLSI guidelines. The efficacy of fluconazole alone and in combination with sodium bicarbonate was evaluated using the time-kill and phospholipase production assays. Eventually, the expression of PLB was assessed using semi-quantitative RT-PCR to investigate the inhibitory properties of fluconazole alone and in combination with sodium bicarbonate against C. glabrata. The fluconazole/sodium bicarbonate combination displayed synergistic and antagonistic effects (FICI= 0.375-4.25). In C. glabrata ATCC, SN 152, and SN 164, the fluconazole/sodium bicarbonate combination exhibited a significant fungicidal activity (p< 0.05) but antagonistic effect in the case of SN 283. With exception of SN 283, a significant reduction was noted in phospholipase production in clinical isolates of C. glabrata treated with fluconazole/sodium bicarbonate combination. The PLB was down-regulated significantly by 0.168-0.515 fold in C. glabrata treated with fluconazole/sodium bicarbonate. The results suggested fluconazole/sodium bicarbonate to have a potential synergistic interaction in C. glabrata, and the underlying mechanism may be associated with phospholipase gene

The secreted acid trehalase encoded by the CgATH1 gene is involved in Candida glabrata virulence

BACKGROUND Candida glabrata yeast is the second cause of candidiasis worldwide. Differs from other yeasts since assimilates only glucose and trehalose (a characteristic used in rapid identification tests for this pathogen) by secreting into the medium a highly active acid trehalase encoded by the CgATH1 gene. OBJECTIVE This study aimed to characterise the function of the acid trehalase in the physiopathology of C. glabrata. METHODS Gene deletion was performed to obtain a mutant ath1Δ strain, and the ability of the ath1Δ strain to grow in trehalase, or the presence of trehalase activity in the ath1Δ yeast cells, was verified. We also tested the virulence of the ath1Δ strain in a murine model of infection. FINDINGS The ath1Δ mutant strain grows normally in the presence of glucose, but loses its ability to grow in trehalose. Due to the high acid trehalase activity present in wild-type cells, the cytoplasmic neutral trehalase activity is only detected in the ath1Δ strain. We also observed a significantly lower virulence of the ath1Δ strain in a murine model of infection with either normal or immunocompromised mice. MAIN CONCLUSIONS The acid trehalase is involved in the hydrolysis of external trehalose by C. glabrata, and the enzyme also plays a major virulence role during infectivity.

Comparative study of Candida by conventional and CHROMagar method in non-denture and denture wearers by oral rinse technique.

Introduction: Candidal species colonizes the oral cavities of healthy individuals without dentures and also of denture wearers. Soft liners and tissue conditioning materials have been found to support the growth of Candida albicans which may predispose to lesions. The most important and common candidal species are C. albicans, C. tropicalis, and C. glabrata. C albicans is usually isolated from both the fitting surface of the denture and the denture-bearing mucosa of the affected patients. The aim of this study was to isolate, quantify, and speciate candidal species in non-denture wearers (controls) and denture wearers (study group) by the oral rinse technique. Isolation was done using Sabouraud dextrose agar (SDA). Speciation was done using conventional methods like the germ tube test, carbohydrate fermentation test, urease test, as well as the CHROMagar method. Aims and Objective: 1) To assess the prevalence of Candida in non-denture wearers and in denture wearers by oral rinse technique, with isolation on SDA; 2) to speciate and quantify Candida in non-denture wearers and denture wearers by using conventional methods (germ tube test, carbohydrate fermentation test, urease test) and the CHROMagar method; 3) to assess the influence of smoking and diabetes on candidal species among the denture wearers; and 4) to assess the sensitivity and specificity of SDA and CHRO Magar Materials and Methods: Salivary samples for Candida evaluation were collected from the subjects in sterile sample containers, using the oral rinse technique. Results: C glabrata was the most commonly found species among denture wearers and non-denture wearers both by conventional and CHROMagar methods. In males, C. albicans was the predominant species, whereas C. glabrata was the predominant species in females. Candidal colonization was higher in denture wearers compared to non-denture wearers, especially among females. The CHROMagar method was more rapid compared to conventional methods. In the present study, CHROMagar Candida showed 100% specificity and 100% sensitivity when compared to SDA and conventional methods.