Candida albicans Biofilms Are Generally Devoid of Persister Cells

Abstract

Candida albicans is known for its ability to form biofilms, which are communities of microorganisms embedded in an extracellular matrix developing on different surfaces. Biofilms are highly tolerant to antifungal therapy. This phenomenon has been partially explained by the appearance of so-called persister cells, phenotypic variants of wild-type cells, capable of surviving very high concentrations of antimicrobial agents. Persister cells in C. albicans were found exceptionally in biofilms, while none were detected in planktonic cultures of this fungus. Yet, this topic remains controversial, as others could not observe persister cells in biofilms formed by the C. albicans SC5314 laboratory strain. Due to ambiguous data in the literature, this work aimed to reevaluate the presence of persister cells in C. albicans biofilms. We demonstrated that the isolation of C. albicans “persister cells” as described previously was likely to be the result of the survival of biofilm cells that were not reached by the antifungal. We tested biofilms of SC5314 and its derivatives, as well as 95 clinical isolates, using an improved protocol, demonstrating that persister cells are not a characteristic trait of C. albicans biofilms. Although some clinical isolates are able to yield survivors upon the antifungal treatment of biofilms, this phenomenon is rather stochastic and inconsistent.

The Postbiotic Activity of Lactobacillus paracasei 28.4 Against Candida auris

“…Persister cells were reported for the first time as a subpopulation of bacteria tolerant to a particular antibiotic that, after removal of the antimicrobial agent, gave rise to a new population of susceptible microbial cells (Bigger, 1944 ). In the clinical setting, persisters are usually associated with recurrent infections and the development of chronic infections (Denega et al, 2019 ). The first report of Candida spp.…”

“…In addition, Al-Dhaheri and Douglas ( 2008 ) showed that not all Candida spp. and strains are able to form persister cells, for example, C. albicans strain SC5314 (Gillum et al, 1984 ), one of the most commonly used C. albicans strains used for molecular genetics studies, is not able to form persister cells in vitro (Denega et al, 2019 ).…”

The importance of antimicrobial resistance in medical mycology

“…Antifungal persistence was associated with biofilms in one study, but it has been more difficult to detect (reviewed in ref. 43) and its relevance remains controversial 44 .…”

Recent Advances and Opportunities in the Study of Candida albicans Polymicrobial Biofilms

“…It will be important to see if this mechanism is also relevant in vivo, where glucose levels are often limited and greater competition for glucose, or co-utilization of alternative carbon sources, could be expected. The role of both bacterial persister cell in antibiotic resistance in the context of monomicrobial biofilms have been studied, however the role of C. albicans persister cells seem to be more controversial with different findings regarding the occurrence of persister cells in C. albicans biofilms (Denega et al, 2019;Galdiero et al, 2020b). However, the role of bacterial (or C. albicans) persister cells in polymicrobial biofilms, especially their influence on drug tolerance, has not been studied yet.…”