Planktonic growth and biofilm formation profiles in Candida haemulonii species complex

Abstract

Candida haemulonii species complex have emerged as multidrug-resistant yeasts able to cause fungemia worldwide. However, very little is known regarding their physiology and virulence factors. In this context, planktonic growth and biofilm formation of Brazilian clinical isolates of Candida haemulonii (n = 5), Candida duobushaemulonii (n = 4), and Candida haemulonii var. vulnera (n = 3) were reported. Overall, the fungal planktonic growth curves in Sabouraud dextrose broth reached the exponential phase in 48 h at 37°C. All the clinical isolates formed biofilm on polystyrene in a time-dependent event, as judged by the parameters evaluated: biomass (crystal violet staining), metabolic activity (XTT reduction), and extracellular matrix (safranin incorporation). No statistically significant differences were observed when the average measurements among the three Candida species were compared regarding both planktonic and biofilm lifestyles; however, typical isolate-specific differences were clearly noticed in fungal growth kinetics.

Antifungal Potential of Copper(II), Manganese(II) and Silver(I) 1,10-Phenanthroline Chelates Against Multidrug-Resistant Fungal Species Forming the Candida haemulonii Complex: Impact on the Planktonic and Biofilm Lifestyles

“…Administered drugs experience reduced access to the pathogen as a result of the presence of a biofilm matrix composed of polysaccharides, carbohydrates, proteins and DNA. Besides that, the presence of a biofilm on an implanted medical device may become a reservoir of pathogenic cells that are released to the bloodstream, resulting in dissemination to internal sites and organs (Bujdáková, 2016; Ramos et al, 2017). Candida strains with an inherent ability to establish a biofilm are associated with a higher mortality rate when compared to strains incapable of biofilm formation (Peeters et al, 2008; Garcia-Vidal et al, 2013; Kawai et al, 2015; Rajendran et al, 2016).…”

“…Candida strains with an inherent ability to establish a biofilm are associated with a higher mortality rate when compared to strains incapable of biofilm formation (Peeters et al, 2008; Garcia-Vidal et al, 2013; Kawai et al, 2015; Rajendran et al, 2016). The C. haemulonii complex has a considerable biofilm-forming capacity (Bujdáková, 2016; Ramos et al, 2017) and, curiously, the presence of a central venous catheter was mentioned in all of the fungemia case reports regarding these species between 2002 and 2010 (Khan et al, 2007; Almeida et al, 2012; Cendejas-Bueno et al, 2012; Muro et al, 2012). One documented case also describes an outbreak in neonatal patients who were receiving total parenteral nutrition (Kim et al, 2009).…”

“…Given the epidemiological profile of the C. haemulonii complex and the fact that it is resistant to such a broad spectrum of the state-of-the-art antifungals (e.g., amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, micafungin, and caspofungin) (Giusiano et al, 2005; Khan et al, 2007; Kim et al, 2009; Ruan et al, 2010), it is imperative that the scientific community examine alternative therapeutic paths for it treatment. Aggravating this scenario, recently, our research group described the ability of C. haemulonii species complex to form biofilm on inert substrate (Ramos et al, 2017). From a medical viewpoint, the microbial biofilm architecture is a complex and robust structure, which is extremely resistant to different classes of drugs (e.g., antifungals and disinfectants), host immune attack (e.g., antibodies, antimicrobial peptides, and complement proteins) and several hostile environmental stressors (e.g., dehydration and radiation; Nett, 2014; Ramage et al, 2014; Mello et al, 2017).…”

“…From a medical viewpoint, the microbial biofilm architecture is a complex and robust structure, which is extremely resistant to different classes of drugs (e.g., antifungals and disinfectants), host immune attack (e.g., antibodies, antimicrobial peptides, and complement proteins) and several hostile environmental stressors (e.g., dehydration and radiation; Nett, 2014; Ramage et al, 2014; Mello et al, 2017). Anti-biofilm strategies able to prevent and/or eradicate fungal biofilms in medical devices are urgently required (Ramage et al, 2014; Ramos et al, 2017). …”

Biofilm Formed by Candida haemulonii Species Complex: Structural Analysis and Extracellular Matrix Composition

“…In this sense, biofilm formation is an unquestionable and well-known virulence attribute associated with both bacterial and fungal infections around the world. Biofilm formation by the C. haemulonii species complex has already been reported based on the use of classical methodologies [1,7,16], but there is lack of information about the characteristics of the biofilm formed by these fungi. Indeed, it is believed that biofilm lifestyle is the preferred organization mode of microorganisms in nature, which is characterized by a highly complex structured community of microorganisms that interact with each other and with a biotic/abiotic surface, covered by a self-produced extracellular matrix (ECM) composed mainly of proteins, polysaccharides, lipids, nucleic acids, minerals, and water [17,18].…”