Evaluation of Virulence Factors In vitro, Resistance to Osmotic Stress and Antifungal Susceptibility of Candida tropicalis Isolated from the Coastal Environment of Northeast Brazil

Abstract

Several studies have been developed regarding human health risks associated with the recreational use of beaches contaminated with domestic sewage. These wastes contain various micro-organisms, including Candida tropicalis. In this context, the objective of this study was to characterize C. tropicalis isolates from the sandy beach of Ponta Negra, Natal, Rio Grande do Norte, Brazil, regarding the expression of in vitro virulence factors, adaptation to osmotic stress and susceptibility to antifungal drugs. We analyzed 62 environmental isolates and observed a great variation among them for the various virulence factors evaluated. In general, environmental isolates were more adherent to human buccal epithelial cells (HBEC) than C. tropicalis ATCC13803 reference strain, and they also showed increased biofilm production. Most of the isolates presented wrinkled phenotypes on Spider medium (34 isolates, 54.8%). The majority of the isolates also showed higher proteinase production than control strains, but low phospholipase activity. In addition, 35 isolates (56.4%) had high hemolytic activity (hemolysis index > 0.55). With regard to C. tropicalis resistance to osmotic stress, 85.4% of the isolates were able to grow in a liquid medium containing 15% sodium chloride. The strains were highly resistant to the azoles tested (fluconazole, voriconazole and itraconazole). Fifteen strains were resistant to the three azoles tested (24.2%). Some strains were also resistant to amphotericin B (14 isolates; 22.6%), while all of them were susceptible for the echinocandins tested, except for a single strain of intermediate susceptibility to micafungin. Our results demonstrate that C. tropicalis isolated from the sand can fully express virulence attributes and showed a high persistence capacity on the coastal environment; in addition of showing high minimal inhibitory concentrations to several antifungal drugs used in current clinical practice, demonstrating that environmental isolates may have pathogenic potential.

Anthropogenic Litter on Beaches With Different Levels of Development and Use: A Snapshot of a Coast in Pernambuco (Brazil)

“…Although food scraps (the most abundant items related to beach users) degrade faster than other types of anthropogenic litter, they are ideal substrates for the proliferation of pathogenic microorganisms (Zuza-Alves et al, 2016) and serve as a food source for many disease-spreading animals, such as insects, rats, and pigeons (Araújo et al, 2012).…”

“…Anthropogenic litter may be responsible for economic, social, and environmental damage, such as expenditure incurred by public agencies to clean beaches instead of using these funds for other areas in need (Araújo and Costa, 2006), loss of aesthetic value and tourism potential of the sites (Araújo and Costa, 2007a;Silva-Cavalcanti et al, 2013), pollution by pathogenic agents (Zuza-Alves et al, 2016), and damage to marine biota by accidental ingestion and entanglement, which can cause choking, injury, illness, and death of marine organisms (Moore, 2008;Attademo et al, 2015;Mendes et al, 2015). Along with other forms of extremely harmful pollution, plastics present in anthropogenic litter are one of the biggest concerns for the ocean in terms of marine pollution because of their intrinsic properties, such as low density (which facilitates their fluctuation and consequent dispersion), persistence, cumulative build-up over time, and widespread use (Moore, 2008;Corcoran et al, 2009;Thompson et al, 2009;Scisciolo et al, 2016).…”

Early Virulence Predictors during the Candida Species–Galleria mellonella Interaction

“…This variation has been also reported for different C. tropicalis strains used in the murine model of systemic candidemia [ 56 ]. The expression of traditional virulence factors, such as adhesion and secretion of hydrolytic enzymes varies among C. tropicalis clinical and environmental isolates [ 57 , 58 ], and this could partially explain the behavior of the strains analyzed here when inoculated within the larvae. In addition, multilocus sequence typing analyses have demonstrated that isolates from this species can be grouped in at least three clades [ 34 ], which underscore genome plasticity that could be behind these differences in virulence.…”

Environmental and genetic regulation of white‐opaque switching in Candida tropicalis

“…To survive and propagate, organisms must adapt their behaviors to the environment. The closely related species, Candida albicans and Candida tropicalis , are two important opportunistic fungal pathogens of humans, but differ in their natural habitats (Hagler and Mendonca‐Hagler, ; Kutty and Philip, ; Kothavade et al ., ; Odds, ; Berman, ; Zuza‐Alves et al ., ). C. albicans primarily resides in human or warm‐blooded animal hosts as a commensal organism and has rarely been isolated from non‐contaminated environments, whereas C. tropicalis is not only a commensal but also exists ubiquitously in the environment [(Odds, ) and the LIFE website, http://www.life-worldwide.org/].…”

“…C. albicans primarily resides in human or warm‐blooded animal hosts as a commensal organism and has rarely been isolated from non‐contaminated environments, whereas C. tropicalis is not only a commensal but also exists ubiquitously in the environment [(Odds, ) and the LIFE website, http://www.life-worldwide.org/]. C. tropicalis , in particular, is widely distributed in tropical and subtropical marine environments (Kutty and Philip, ; Zuza‐Alves et al ., ) such as seawater, sea sediments and beaches. The underlying mechanisms that contribute to the different environmental adaptation abilities of C. albicans and C. tropicalis remain unclear.…”