Ortega-Riveros M et al. (2017) Mycopathologia "Usefulness of the Non-conventional Caenorhabditis elegans Model to Assess Candida Virulence."

Marcos-Arias C, Ortega-Riveros M, Ezpeleta G, Quindos G, Eraso E, De-la-Pinta I

[Mycopathologia, 2017]

Invasive candidiasis is caused mainly by Candida albicans, but other Candida species have increasing etiologies. These species show different virulence and susceptibility levels to antifungal drugs. The aims of this study were to evaluate the usefulness of the non-conventional model Caenorhabditis elegans to assess the in vivo virulence of seven different Candida species and to compare the virulence in vivo with the in vitro production of proteinases and phospholipases, hemolytic activity and biofilm development capacity. One culture collection strain of each of seven Candida species (C. albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida metapsilosis, Candida orthopsilosis and Candida parapsilosis) was studied. A double mutant C. elegans AU37 strain (glp-4;sek-1) was infected with Candida by ingestion, and the analysis of nematode survival was performed in liquid medium every 24h until 120h. Candida establishes a persistent lethal infection in the C. elegans intestinal tract. C. albicans and C. krusei were the most pathogenic species, whereas C. dubliniensis infection showed the lowest mortality. C. albicans was the only species with phospholipase activity, was the greatest producer of aspartyl proteinase and had a higher hemolytic activity. C. albicans and C. krusei caused higher mortality than the rest of the Candida species studied in the C. elegans model of candidiasis.

Kunyeit L et al. (2019) MBio "Probiotic Yeasts Inhibit Virulence of Non-albicans Candida Species."

Kunyeit L, Rao RP, Anu-Appaiah KA, Kurrey NK

[MBio, 2019]

Systemic infections of <i>Candida</i> species pose a significant threat to public health. Toxicity associated with current therapies and emergence of resistant strains present major therapeutic challenges. Here, we report exploitation of the probiotic properties of two novel, food-derived yeasts, <i>Saccharomyces cerevisiae</i> (strain KTP) and <i>Issatchenkia occidentalis</i> (strain ApC), as an alternative approach to combat widespread opportunistic fungal infections. Both yeasts inhibit virulence traits such as adhesion, filamentation, and biofilm formation of several non-<i>albicans Candida</i> species, including <i>Candida tropicalis</i>, <i>Candida krusei</i>, <i>Candida glabrata</i>, and <i>Candida parapsilosis</i> as well as the recently identified multidrug-resistant species <i>Candida auris</i> They inhibit adhesion to abiotic surfaces as well as cultured colon epithelial cells. Furthermore, probiotic treatment blocks the formation of biofilms of individual non-<i>albicans Candida</i> strains as well as mixed-culture biofilms of each non-<i>albicans Candida</i> strain in combination with <i>Candida albicans</i> The probiotic yeasts attenuated non-<i>albicans Candida</i> infections in a live animal. <i>In vivo</i> studies using <i>Caenorhabditis elegans</i> suggest that exposure to probiotic yeasts protects nematodes from infection with non-<i>albicans Candida</i> strains compared to worms that were not exposed to the probiotic yeasts. Furthermore, application of probiotic yeasts postinfection with non-<i>albicans Candida</i> alleviated pathogenic colonization of the nematode gut. The probiotic properties of these novel yeasts are better than or comparable to those of the commercially available probiotic yeast <i>Saccharomyces boulardii</i>, which was used as a reference strain throughout this study. These results indicate that yeasts derived from food sources could serve as an effective alternative to antifungal therapy against emerging pathogenic <i>Candida</i> species.<b>IMPORTANCE</b> Non-<i>albicans Candida</i>-associated infections have emerged as a major risk factor in the hospitalized and immunecompromised patients. Besides, antifungal-associated complications occur more frequently with these non-<i>albicans Candida</i> species than with <i>C. albicans</i> Therefore, as an alternative approach to combat these widespread non-<i>albicans Candida</i>-associated infections, here we showed the probiotic effect of two yeasts, <i>Saccharomyces cerevisiae</i> (strain KTP) and <i>Issatchenkia occidentalis</i> (ApC), in preventing adhesion and biofilm formation of five non-<i>albicans Candida</i> strains, <i>Candida tropicalis</i>, <i>Candida krusei</i>, <i>Candida glabrata</i>, <i>Candida parapsilosis</i>, and <i>Candida auris</i> The result would influence the current trend of the conversion of conventional antimicrobial therapy into beneficial probiotic microbe-associated antimicrobial treatment.

Thevissen K et al. (2011) Bioorg Med Chem Lett "Novel fungicidal benzylsulfanyl-phenylguanidines."

Cammue BP, Van Minnebruggen G, De Brucker K, Thevissen K, Francois IE, De Vos D, Meert W, Meert EM, Borgers M, Cos P, Pellens K, Levin J, Maes L, Vroome V, Chow KK

[Bioorg Med Chem Lett, 2011]

A series of substituted benzylsulfanyl-phenylamines was synthesized, of which four substituted benzylsulfanyl-phenylguanidines (665, 666, 667 and 684) showed potent fungicidal activity (minimal fungicidal concentration, MFC 10 M for Candida albicans and Candida glabrata). A benzylsulfanyl-phenyl scaffold with an unsubstituted guanidine resulted in less active compounds (MFC=50-100 M), whereas substitution with an unsubstituted amine group resulted in compounds without fungicidal activity. Compounds 665, 666, 667 and 684 also showed activity against single C. albicans biofilms and biofilms consisting of C. albicans and Staphylococcus epidermidis (minimal concentration resulting in 50% eradication of the biofilm, BEC50 121 M for both biofilm setups). Compounds 665 and 666 combined potent fungicidal (MFC=5 M) and bactericidal activity (minimal bactericidal concentration, MBC for S. epidermidis 4 M). In an in vivo Caenorhabditis elegans model, compounds 665 and 667 exhibited less toxicity than 666 and 684. Moreover, addition of those compounds to Candida-infected C. elegans cultures resulted in increased survival of Candida-infected worms, demonstrating their in vivo efficacy in a mini-host model.

Aguiar Cordeiro R et al. (2018) Future Microbiol "-lactam antibiotics & vancomycin increase the growth & virulence of Candida spp."

Sales JA, Aguiar Cordeiro R, Gadelha Rocha MF, de Jesus Evangelista AJ, Silva Franco JD, de Alencar LP, Costa Sidrim JJ, Leite Mendes PB, Colares de Andrade AR, de Oliveira JS, Souza Collares Maia Castelo-Branco D, Nogueira Brilhante RS, Serpa R, Carneiro Camara LM

[Future Microbiol, 2018]

AIM: To investigate the direct effect of antibiotics on growth and virulence of the major Candida species associated with invasive infections. MATERIALS &amp; METHODS: Cefepime, imipenem, meropenem, amoxicillin and vancomycin were tested at twofold the peak plasma concentration (2x PP) and the peak plasma concentration (PP). The effects of antibiotics on Candida albicans, Candida parapsilosis, Candida krusei and Candida tropicalis were investigated by colony counting, flow cytometry, proteolytic activity and virulence in Caenorhabditis elegans. RESULTS: Antibiotics increase growth and proteolytic activity of Candida spp; In addition, amoxicillin potentiates virulence ofC. krusei and C. tropicalis against Caenorhabditis elegans. CONCLUSION: These results suggest that antimicrobial therapy may have a direct effect on the pathophysiology of invasive fungal infections in patients at risk.

Andrade G et al. (2020) J Fungi (Basel) "Brazilian Copaifera Species: Antifungal Activity against Clinically Relevant Candida Species, Cellular Target, and In Vivo Toxicity."

Scorzoni L, Bastos JK, Carvalho MTM, Mendes-Giannini MJS, Pires RH, Martins CHG, Orlando HCS, Veneziani RCS, Ambrosio SR, Andrade G, Abrao F, Pedroso RS

[J Fungi (Basel), 2020]

Plants belonging to the genus <i>Copaifera</i> are widely used in Brazil due to their antimicrobial properties, among others. The re-emergence of classic fungal diseases as a consequence of antifungal resistance to available drugs has stimulated the search for plant-based compounds with antifungal activity, especially against <i>Candida</i>. The <i>Candida</i>-infected <i>Caenorhabditis elegans</i> model was used to evaluate the in vitro antifungal potential of <i>Copaifera</i> leaf extracts and trunk oleoresins against <i>Candida</i> species. The <i>Copaifera</i> leaf extracts exhibited good antifungal activity against all <i>Candida</i> species, with MIC values ranging from 5.86 to 93.75 g/mL. Both the <i>Copaifera paupera</i> and <i>Copaifera reticulata</i> leaf extracts at 46.87 g/mL inhibited <i>Candida glabrata</i> biofilm formation and showed no toxicity to <i>C. elegans.</i> The survival of <i>C. glabrata</i>-infected nematodes increased at all the tested extract concentrations. Exposure to <i>Copaifera</i> leaf extracts markedly increased <i>C. glabrata</i> cell vacuolization and cell membrane damage. Therefore, <i>Copaifera</i> leaf extracts are potential candidates for the development of new and safe antifungal agents.

Hernando-Ortiz A et al. (2020) Antimicrob Agents Chemother "Caenorhabditis elegans as a model system to assess Candida glabrata, Candida nivariensis and Candida bracarensis virulence and antifungal efficacy."

Mateo E, Ortega-Riveros M, De-la-Pinta I, Eraso E, Quindos G, Hernando-Ortiz A

[Antimicrob Agents Chemother, 2020]

Although <i>Candida albicans</i> remains the major etiological agent of invasive candidiasis, <i>Candida glabrata</i> and other emerging species of <i>Candida</i> are increasingly isolated. This species is the second most prevalent cause of candidiasis in many regions of the world. However, clinical isolates of <i>Candida nivariensis</i> and <i>Candida bracarensis</i> can be misidentified and are underdiagnosed due to shared phenotypic traits with <i>C. glabrata</i> Little is known about both cryptic species. Pathogenesis studies are therefore needed to understand their virulence traits and their susceptibility to antifungal drugs. The susceptibility of <i>Caenorhabditis elegans</i> to different <i>Candida</i> species makes this nematode an excellent model for assessing host-fungal interactions. We evaluated the usefulness of <i>C. elegans</i> as a nonconventional host model to analyze the virulence of <i>C. glabrata</i>, <i>C. nivariensis</i> and <i>C. bracarensis</i> The three species caused candidiasis and the highest virulence of <i>C. glabrata</i> was confirmed. Furthermore, we determined the efficacy of current antifungal drugs against the infection caused by these species in the <i>C. elegans</i> model. Amphotericin B and azoles showed the highest activity against <i>C. glabrata</i> and <i>C. bracarensis</i> infections, while echinocandins were more active for treating those caused by <i>C. nivariensis. C. elegans</i> proved to be a useful model system for assessing the pathogenicity of these closely related species.

Muthamil S et al. (2018) Front Microbiol "Synergistic Effect of Quinic Acid Derived From Syzygium cumini and Undecanoic Acid Against Candida spp. Biofilm and Virulence."

Pandian SK, Balamurugan K, Muthamil S, Balasubramaniam B

[Front Microbiol, 2018]

In recent decades, fungal infections have incredibly increased with <i>Candida</i> genus as the major cause of morbidity and mortality in hospitalized and immunocompromised patients. Most of the <i>Candida</i> species are proficient in biofilm formation on implanted medical devices as well as human tissues. Biofilm related <i>Candida</i> infections are very difficult to treat using common antifungal agents owing to their increased drug resistance. To address these issues, the present study investigated the antibiofilm and antivirulent properties of <i>Syzygium cumini</i> derived quinic acid in combination with known antifungal compound undecanoic acid. Initially, antibiofilm potential of <i>S. cumini</i> leaf extract was assessed and the active principles were identified through gas chromatography and mass spectrometry analysis. Among the compounds identified, quinic acid was one of the major compounds. The interaction between quinic acid and undecanoic acid was found to be synergistic in the Fractional inhibitory concentration index (0.5). Results of <i>in vitro</i> assays and gene expression analysis suggested that the synergistic combinations of quinic acid and undecanoic acid significantly inhibited virulence traits of <i>Candida</i> spp. such as the biofilm formation, yeast-to-hyphal transition, extracellular polymeric substances production, filamentation, secreted hydrolases production and ergosterol biosynthesis. In addition, result of <i>in vivo</i> studies using <i>Caenorhabditis elegans</i> demonstrated the non-toxic nature of QA-UDA combination and antivirulence effect against <i>Candida</i> spp. For the first time, synergistic antivirulence ability of quinic acid and undecanoic acid was explored against <i>Candida</i> spp. Thus, results obtained from the present study suggest that combination of phytochemicals might be used an alternate therapeutic strategy for the prevention and treatment of biofilm associated <i>Candida</i> infection.

Luca V et al. (2014) Cell Mol Life Sci "Anti-Candida activity of 1-18 fragment of the frog skin peptide esculentin-1b: in vitro and in vivo studies in a Caenorhabditis elegans infection model."

Luca V, Palleschi C, Olivi M, Uccelletti D, Mangoni ML, Di Grazia A

[Cell Mol Life Sci, 2014]

Candida albicans represents one of the most prevalent species causing life-threatening fungal infections. Current treatments to defeat Candida albicans have become quite difficult, due to their toxic side effects and the emergence of resistant strains. Antimicrobial peptides (AMPs) are fascinating molecules with a potential role as novel anti-infective agents. However, only a few studies have been performed on their efficacy towards the most virulent hyphal phenotype of this pathogen. The purpose of this work is to evaluate the anti-Candida activity of the N-terminal 1-18 fragment of the frog skin AMP esculentin-1b, Esc(1-18), under both in vitro and in vivo conditions using Caenorhabditis elegans as a simple host model for microbial infections. Our results demonstrate that Esc(1-18) caused a rapid reduction in the number of viable yeast cells and killing of the hyphal population. Esc(1-18) revealed a membrane perturbing effect which is likely the basis of its mode of action. To the best of our knowledge, this is the first report showing the ability of a frog skin AMP-derived peptide (1) to kill both growing stages of Candida; (2) to promote survival of Candida-infected living organisms and (3) to inhibit transition of these fungal cells from the roundish yeast shape to the more dangerous hyphal form at sub-inhibitory concentrations.

Souza ACR et al. (2018) Genes (Basel) "Pathogenesis of the Candida parapsilosis Complex in the Model Host Caenorhabditis elegans."

Colombo AL, Fuchs BB, Jayamani E, Mylonakis E, Souza ACR, Alves VS

[Genes (Basel), 2018]

<i>Caenorhabditis</i><i>elegans</i> is a valuable tool as an infection model toward the study of <i>Candida</i> species. In this work, we endeavored to develop a <i>C</i>. <i>elegans</i>-<i>Candida</i><i>parapsilosis</i> infection model by using the fungi as a food source. Three species of the C. parapsilosis complex (<i>C.</i><i>parapsilosis</i> (<i>sensu</i><i>stricto</i>), <i>Candida</i><i>orthopsilosis</i> and <i>Candida</i><i>metapsilosis</i>) caused infection resulting in <i>C. elegans</i> killing. All three strains that comprised the complex significantly diminished the nematode lifespan, indicating the virulence of the pathogens against the host. The infection process included invasion of the intestine and vulva which resulted in organ protrusion and hyphae formation. Importantly, hyphae formation at the vulva opening was not previously reported in <i>C</i>. <i>elegans</i>-<i>Candida</i> infections. Fungal infected worms in the liquid assay were susceptible to fluconazole and caspofungin and could be found to mount an immune response mediated through increased expression of <i>cnc</i>-<i>4</i>, <i>cnc</i>-<i>7</i>, and <i>fipr</i><i>-</i><i>22</i>/<i>23</i>. Overall, the <i>C</i>. <i>elegans</i>-<i>C</i>. <i>parapsilosis</i> infection model can be used to model <i>C</i>. <i>parapsilosis</i> host-pathogen interactions.

Eldesouky HE et al. (2017) Antimicrob Agents Chemother "Reversal of azole resistance in Candida albicans by sulfa antibacterial drugs."

Mayhoub A, Eldesouky HE, Hazbun TR, Seleem MN

[Antimicrob Agents Chemother, 2017]

Invasive candidiasis presents an emerging global public health challenge due to the emergence of resistance to the frontline treatment options, such as fluconazole. Hence, the identification of other compounds capable of pairing with fluconazole and averting azole-resistance would potentially prolong the clinical utility of this important group. In an effort to repurpose drugs in the field of antifungal drug discovery, we explored sulfa antibacterial drugs for the purpose of reverting azole resistance in Candida In this study, we assembled and investigated a library of 21 sulfa antibacterial drugs for their ability to restore fluconazole sensitivity in Candida albicans Surprisingly, the majority of assayed sulfa drugs (15) were found to exhibit synergistic relationships with fluconazole by checkerboard assay with FIC values ranging from &lt; 0.0312 to 0.25. Remarkably, five sulfa drugs, were able to revert azole resistance in a clinically achievable range. The structure-activity-relationships (SAR) of the amino benzene sulfonamide scaffold as antifungal agents were studied. We also identified the possible mechanism of the synergistic interaction of sulfa antibacterial drugs with azole antifungal drugs. Furthermore, the ability of sulfa antibacterial drugs to inhibit Candida biofilm by 40% in vitro was confirmed. In addition, effect of sulfa-fluconazole combination on Candida growth kinetics and efflux machinery was explored. Finally, using a Caenorhabditis elegans infection model, we demonstrated that the sulfa-fluconazole combination does possess potent antifungal activity in vivo reducing Candida in infected worms by 50% compared to the control.