In vitro susceptibility of Candida species to lysozyme.

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Anti-candida activity of murine bronchoalveolar lavage fluid

Respiratory secretions provide an efficient method for protecting the large surface area of the lower respiratory tract. To determine whether lung secretions contribute to antifungal defences, murine bronchoalveolar lavage fluid (BLF) was tested for anti-candidal activity against 49 oral and vaginal isolates belonging to six different Candida species. The yeasts were incubated in unconcentrated, cell-free lavage fluid from Sprague-Dawley rats and then cultured quantitatively to measure residual viability. Experiments with C. albicans indicated that sensitivity to BLF increased in a time- and dose-dependent manner. This activity was heat-stable (56°C) and consistent, irrespective of whether the BLF was derived from rats inoculated (orally) with candida or the uninoculated controls. Of the Candida spp. examined, C. albicans was the most susceptible followed by C. parapsilosis and C. tropicalis, whereas C. krusei, C. guilliermondii and C. glabrata were highly resistant. However, there were differences in susceptibility to BLF among different isolates within a given species. These results indicate that a heat-stable, soluble factor(s) in murine lavage fluid may suppress candidal colonisation of the lower respiratory tract and contribute to the defence mechanisms of the lungs.link_to_subscribed_fulltex

Adhesion of Candida-Albicans to Buccal Epithelial-Cells Exposed to Chlorhexidine Gluconate

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Fungicidal effect of three new synthetic cationic peptides against Candida albicans

OBJECTIVE: Peptide antibiotics are considered a new class of antifungal agents. Of these, an α-helical, cationic peptide termed Dhvar 4, a relative of salivary histatin has been shown to be an antifungal of relatively high potency. Similarly, lactoferricin B (LFB) and a derivative thereof, LFB(17-30), disrupts the fungal cell membrane and acts against Candida albicans. As Dhvar 4 and LFB(17-30), exhibit almost identical amino acid sequences at their C-terminal, we hypothesized that laboratory synthesis of peptides with an α-helical structure and having similar amphipathic properties could lead to products with candidacidal activity. Hence, three such peptides - JH8194, JH8195 and JH 8944, were synthesized and their antifungal properties compared with recognized antifungals LFB, LFB(17-30), human lactoferricin (LFH), Histatin-5 and Dhvar 4, against two isolates of C. albicans. MATERIALS AND METHODS: The antifungal agents were synthesized and their secondary structures evaluated according to a previously described protocol of Situ and Bobek (2000) Antimicrob Agents Chemother 44: 1485-1493. The C. albicans strains were oral isolates from a human immunodeficiency virus-infected (isolate A2) and a healthy (A6) individual. A standard concentration of yeasts was exposed to a range of dilutions of the agents for a specific duration and the cell death (viability) in terms of the resultant colony forming units ml-1 was quantified. RESULTS: Dhvar 4, showed the most α-helical propensity, and was the least fungicidal while LFB and LFB(17-30) showed the highest antifungal potential, and demonstrated total kill of A6, and A2 at 5 and 10 μM concentrations, respectively whilst LFH killed both isolates at a 10 μM concentration. Of the three new synthetic peptides, JH 8194 was the most potent (total kill of A6/A2 strains at 1.25/2.5 μM), followed by JH 8195 (total kill of A6/A2 strains at 5/10 μM while JH 8944 was the least potent as a 25 μM concentration was required to kill either strain of Candida. On further analyses of the relationship between pl value of the peptides and their anticandicidal activity, a significant positive correlation was noted. In order to rule out a cytotoxic effect of the new synthetic peptides we compared the fungicidal and hemolytic activities under similar incubation conditions using freshly isolated erythrocytes and all three peptides exhibited no detectable hemolysis upto an concentration of 100 μM in contrast to the polyene antifungal amphotericin B that elicited significant initiation of hemolysis at a concentration of 5.0 μM. CONCLUSION: Our data suggest that laboratory synthesis of agents with an α-helical structure and having amphipathic properties similar to known, natural antifungal agents may be a promising avenue to generate products with improved antifungal activity.link_to_subscribed_fulltex