Silicone colonization by non-Candida albicans Candida species in the presence of urine

Abstract

Urinary tract infections (UTIs) are the most common nosocomial infections and 80 % are related to the use of urinary catheters. Furthermore, Candida species are responsible for around 15 % of UTIs and an increasing involvement of non-Candida albicans Candida (NCAC) species (e.g. Candida glabrata, Candida tropicalis and Candida parapsilosis) has been recognized. Given the fact that silicone is frequently used in the manufacture of urinary catheters, the aim of this work was to compare both the adhesion and biofilm formation on silicone of different urinary clinical isolates of NCAC species (i.e. C. glabrata, C. tropicalis and C. parapsilosis) in the presence of urine. Several clinical isolates of NCAC species recovered from patients with UTIs, together with reference strains of each species, were examined. Adhesion and biofilm formation were performed in artificial urine and the biofilm biomass was assessed by crystal violet staining. Hydrophobicity and surface charge of cells was determined by measuring contact angles and zeta potential, respectively. The number of viable cells in biofilms was determined by enumeration of c.f.u. after appropriate culture. The biofilm structure was also examined by confocal laser scanning microscopy (CLSM). The results showed that all isolates adhered to silicone in a species-and strain-dependent manner with C. parapsilosis showing the lowest and C. glabrata the highest levels of adhesion. However, these differences in adhesion abilities cannot be correlated with surface properties since all strains examined were hydrophilic and exhibited a similar zeta potential. Despite a higher number of cultivable cells being recovered after 72 h of incubation, stronger biofilm formation was not observed and CLSM showed an absence of extracellular polymeric material for all isolates examined. In summary, this work demonstrated that all tested NCAC species were able to adhere to and survive on silicone in the presence of urine. Furthermore, C. glabrata strains presented higher colonization abilities than C. tropicalis and C. parapsilosis strains, a fact that might explain the larger role of C. glabrata colonization and disseminated infections in hospitalized and catheterized patients. INTRODUCTIONNosocomial infections constitute a serious public health problem, as they are a major cause of morbidity and mortality, and cause an increased time of hospitalization with associated enhanced healthcare costs (Tamura et al., 2003). Urinary tract infection (UTI) is one of the most common types of nosocomial infections (Schaberg et al., 1991;Tamura et al., 2003) and more than 80 % of nosocomial UTIs are related to the use of medical devices such as urinary catheters (Febré et al., 1999;Harris et al., 1999;Douglas, 2002;Chow et al., 2008). Furthermore, Candida species are responsible for around 80 % of fungal infections in the hospital environment and 10-15 % of UTIs are caused by these micro-organisms (Amer et al., 2004). Although the majority of infections are caused by Candida albicans (Richards et a...

Characterization of phenolic compounds in wild medicinal flowers from Portugal by HPLC–DAD–ESI/MS and evaluation of antifungal properties

“…However, the prevalence of opportunistic fungal infections has been increasing dramatically over the recent decades and this is particularly evident in immunocompromised individuals, where these species become frequently opportunistic pathogens (Pfaller and Diekema 2007). Although, Candida albicans has been regarded as the most common causative agent of fungal infection in humans, nowadays other non-Candida albicans Candida (NCAC) species such as Candida glabrata, Candida tropicalis, and Candida parapsilosis, are emerging as significant nosocomial pathogens (Silva et al, 2010). Moreover, NCAC species tend to be inherently less susceptible to the available antifungal drugs like the azole drugs and their derivatives, which continue to dominate as the antifungal agents of choice against Candida-related infections (Redding et al, 2002;Hajj eh et al, 2004;Ruhnke, 2006).…”

In Vitro Analysis of Finasteride Activity against Candida albicans Urinary Biofilm Formation and Filamentation

“…Urinary candidiasis is an increasingly common in hospitalized patients (4,5). Candiduria may present as asymptomatic colonization, urinary tract infection, or disseminated candidiasis (34).…”

“…For the studies on the treatment of mature biofilms, the cells were incubated in urine medium in a 96-well microplate to allow the formation of mature biofilms for 24 h of incubation at 37°C. Next, the wells were gently washed and the biofilms were incubated for another 24 h at 37°C with increasing log 2 concentrations of FIN (2,4,8,16,32,64,128, and 256 mg/liter in urine medium). For both the prevention and treatment of biofilm studies, the metabolic activity within the biofilms was measured using the XTT reduction assay.…”

“…C. albicans readily forms biofilms, which are characterized by resistance to standard antifungal therapy and host immune responses (1,2), enabling the colonization of mucosal surfaces, with the potential for subsequent invasion and dissemination. C. albicans also forms biofilms on catheters and medical devices, which are difficult to eradicate unless the device is removed (1)(2)(3)(4)(5)(6)(7). Consequently, these clinical issues have driven the search for novel antifungal therapies directed against biofilm-related C. albicans infections, particularly when device removal or replacement is undesirable or high risk.…”

“…C. albicans is the leading cause of invasive fungal infections in the United States, and it is particularly prevalent in catheter-related urinary tract infections (1)(2)(3)(4)(5)(6). C. albicans readily forms biofilms, which are characterized by resistance to standard antifungal therapy and host immune responses (1,2), enabling the colonization of mucosal surfaces, with the potential for subsequent invasion and dissemination.…”