ABSTRACT
Chitosan is a D-glucosamine polysaccharide derived from chitin that displays an antimicrobial activity against bacteria and fungi. Objective: to evaluate the antifungal effect of high molecular weight chitosan (HMWC) in clinical strains of Candida spp. Methodology: the susceptibility of forty strains of Candida spp. to HMWC was studied (16 C albicans, 11 C glabrata, 5 C. tropicalis, 5 C krusei, 2 C parapsilosis and 2 C.famatd) by broth microdilution at pH 7.0 and pH 4.0. Results: of 40 strains, only 2 were inhibited at pH 7.0 and corresponded to ATCC control strains (C. krusei 6258 and C parapsilosis 22019). On the other hand, 37/40 strains (92.5 percent) were inhibited by concentrations lower than 1.25 mg/mL of HMWC at pH 4.0. Conclusion: these results show that HMWC, presents activity against clinical Candida spp. strains, including C glabrata, and that this activity is present at acid pH (4.0). This compound could potentially be used in vulvovaginal candidiasis since it occurs at pH 4.0-4.5.
Subject(s)
Antifungal Agents/pharmacology , Candida/drug effects , Chitosan/pharmacology , Antifungal Agents/chemistry , Colony Count, Microbial , Candida/classification , Chitosan/chemistry , Molecular Weight , Microbial Sensitivity Tests/methodsABSTRACT
Most surveillance studies have included invasive candidiasis from hospitalized patients. However, no national study has evaluated the species distribution and susceptibility to fluconazole of Candida species isolated from hospitalized and ambulatory patients. Atotal of 166 strains were collected consecutively during a 6 month period. Strains were isolated from vaginal fluid (73.5 percent), uriñe (7.8 percent), lower respiratory tract samples (7.8 percent), blood cultures (4.2 percent), sterile fluids (2.4 percent) and wounds (1.8 percent). Most of the isolates were obtained from ambulatory patients (71.1 percent). The species found were Candida albicans (78.9 percent), C glabrata (8.4 percent), C. tropicalis (6.0 percento), C.famata (1.8 percent), C krusei (1.8 percent), C parapsilosis (1.8 percent) and C. sake (1.2 percent). Fluconazole susceptibility was: 92.3 percento for C. albicans, 85.7 percent for C glabrata (most strains being dose-dependent susceptible), 100 percent) for C parapsilosis and 80 percent) for C tropicalis. Only susceptible strains were isolated from hospitalized children, whereas more resistant strains were isolated from ambulatory adults, mainly from vaginal fluid. In order to identify probable reservoirs of less susceptible strains such as C. glabrata, it would be necessary to include ambulatory isolates in future surveillance studies.
La mayoría de los estudios de vigilancia de levaduras del género Candida se realizan en candidiasis invasora en pacientes hospitalizados; sin embargo, no existen estudios que evalúen simultáneamente la distribución global de especies y susceptibilidad a fluconazol de cepas de Candida aisladas de pacientes hospitalizados y ambulatorios. Se analizaron 166 cepas de Candida, recolectadas consecutivamente en un período de 6 meses, las cuales fueron aisladas de flujo vaginal (73,5 por ciento), orina (7,8 por ciento), muestras respiratorias bajas (7,8 por ciento), hemocultivos (4,2 por ciento), líquidos estériles (2,4 por ciento) y heridas (1,8 por ciento). Un 71,1 por ciento provenía de pacientes ambulatorios. La especies aisladas fueron Candida albicans (78,9 por ciento), C glabrata (8,4 por ciento), C tropicalis (6,0 por ciento), Cfamata (1,8 por ciento), C. krusei (1,8 por ciento), C parapsilosis (1,8 por ciento) y C. sake (1,2 por ciento). Los porcentajes de sensibilidad a fluconazol fueron: 92,3 por cientoo para C. albicans, 85,7 por cientoo para C glabrata (siendo la mayoría sensible dosis dependiente), 100 por ciento) para C parapsilosis y 80 por cientoo para C tropicalis. En los niños, todos hospitalizados, se aislaron sólo cepas sensibles, mientras que en adultos ambulatorios se aislaron más cepas resistentes, fundamentalmente de flujo vaginal. Considerar cepas ambulatorias en futuros estudios de vigilancia permitirían dar cuenta de probables reservónos de cepas más resistentes, como C. glabrata.