[Show abstract][Hide abstract] ABSTRACT: We determined the susceptibility to oxidative stress and assessed the four virulence factors of the 38 Candida glabrata clinical isolates originating from two teaching hospitals in Slovakia. All the isolates were susceptible to hydrogen peroxide, diamide, and 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT) inducing an increased formation of reactive oxygen species in fungal cells. The mean relative cell surface hydrophobicity (CSH) of isolates was 21.9, ranging from 1.92 to 56.96. All isolates showed biofilm formation. A high biofilm formation was observed among 60.5% of isolates. Positive correlations were observed between biofilm formation and moderate values of CSHs. The 76.3% and 84.2% of isolates displayed varying degrees of proteinase and phospholipase activity, respectively. These results demonstrate a differential distribution of factors contributing to virulence of C. glabrata clinical isolates and point to their significance in pathogenesis that would be targeted by novel antifungals.
Full-text · Article · Mar 2011 · Folia Microbiologica
[Show abstract][Hide abstract] ABSTRACT: Treatment of not only bacterial but also fungal infections is currently a growing concern. A major reason is the acquisition of multidrug resistance in both prokaryotic and human cells. The multidrug resistance phenotype is a cellular response to the presence of cytotoxic substances in the environment. The basic mechanism of multidrug resistance is overexpression of the membrane proteins involved in the extrusion of toxic substances outside the cell. The resistance mechanism based on the efflux of inhibitors as a result of the overproduction of transport proteins was also observed in some plant and animal pathogens and human tumour cells. The phenomenon of multidrug resistance associated with an excessive and long-term use of antifungals, in particular of azole derivatives, was also confirmed in the yeast Candida glabrata which is becoming a growing concern for health care professionals. Reduced susceptibility to azole derivatives in particular, a high potential for adapting to stressors, and multiple mechanisms of resistance to structurally and functionally unrelated antifungal drugs make the species C. glabrata a potential threat to hospital patients.
[Show abstract][Hide abstract] ABSTRACT: Candida glabrata is an important human pathogen, and an understanding of the genetic relatedness of its clinical isolates is essential for the prevention and control of fungal infections. In this study, we determined the relatedness of 38 Candida glabrata clinical isolates originating from two teaching hospitals in Slovakia. The 14 different genotypes were found by using microsatellite marker analysis (RPM2, MTI and Cg6) and DNA sequencing for analysis of the entire ERG11 gene. Subsequent sequencing of amplified DNA fragments of the PDR1, NMT1, TRP1 and URA3 loci in ten selected clinical isolates revealed identical DNA sequence profiles in five of them. They displayed the same microsatellite marker sizes and contained the same H576Y amino acid substitution recently described in the Pdr1p multidrug resistance transcription factor responsible for azole resistance. These results demonstrate the genetic diversity of C. glabrata clinical isolates in our hospitals and indicate a common clonal origin of some drug resistant ones.
[Show abstract][Hide abstract] ABSTRACT: Candida glabrata is an important human pathogen that is naturally less susceptible to antimycotics compared with Candida albicans. Ten unmatched C. glabrata clinical isolates were selected from a collection of isolates exhibiting decreased susceptibilities to azole antifungals. Overexpression of the CgPDR1 gene, encoding the main multidrug resistance transcription factor, and its target genes CgCDR1 and CgCDR2, coding for drug efflux transporters, was observed in six fluconazole-resistant isolates. Sequence analysis of the polymerase chain reaction (PCR)-amplified DNA fragments of each isolate's CgPDR1 gene was used to identify two novel L347F and H576Y mutations in CgPdr1p. These proved to be responsible for fluconazole resistance in transformants of the C. glabrata pdr1Delta mutant strain. Five isolates harbouring the H576Y mutation also contained the mutation E502V in CgErg11p 14C-lanosterol-demethylase. Heterologous expression of the CgERG11 mutant allele did not provide evidence for its involvement in azole resistance. In four fluconazole-sensitive isolates that were itraconazole-resistant, slightly enhanced CgCDR2 expression was observed. No upregulation of the CgERG11 gene was observed in any of the ten isolates. The results demonstrate that decreased susceptibilities of C. glabrata clinical isolates to azole antifungals mainly results from gain-of-function mutations in the gene encoding the CgPdr1p transcription factor.
Full-text · Article · Mar 2009 · International journal of antimicrobial agents