title: Heterogeneity in antifungal susceptibility of clones of Candida albicans isolated on single and sequential visits from a HIV-infected southern Chinese cohort.
abstract: The increased frequency and severity of candidal infections in human immunodeficiency virus (HIV)-infected individuals has prompted the wide use of antifungals, such as amphotericin B, ketoconazole, and fluconazole, resulting in the emergence of drug-resistant strains of Candida albicans. To study this phenomenon in an ethnic Chinese cohort, we isolated multiple colonies of Candida from the oral cavities of 16 HIV-infected patients on single and subsequent sequential visits over a period of 12 months. Ten of the 16 patients had sporadic episodes of oropharyngeal candidiasis (Group A), while the remainder were asymptomatic with respect to this condition (Group B). Oral rinses were collected and immediately processed in the laboratory for the isolation of C. albicans in a standard manner. A total of 433 C. albicans isolates were tested for their susceptibility to amphotericin B, ketoconazole and fluconazole by an agar diffusion method using the commercially available E-test. All tested isolates demonstrated variable susceptibility to amphotericin B, ketoconazole and fluconazole. The minimum inhibitory concentration (MIC) of the isolates for amphotericin B, ketoconazole and fluconazole ranged from <0.002-1.5 microg/ml, <0.002-4.0 microg/ml and <0.016-32 microg/ml, respectively. Sequential isolates of a few patients demonstrated variable susceptibility to all the antifungals, and no discernible MIC pattern emerged either in group A or B over time. Interestingly, significant variation in antifungal susceptibility was also noted in isolates obtained from the same patient on a single visit. Sequential yeast isolates in 9 of 16 patients (56%) demonstrated significant differences in MIC within and between visits for both amphotericin B and ketoconazole, while a lower percentage--44%(7/16)--exhibited this trait for fluconazole. Our study demonstrates the diversity in antifungal susceptibility in either commensal or "infective" oral strains of C. albicans in HIV disease, and shows the need for vigilance for the emergence of resistant strains, and for frequent antifungal susceptibility studies.
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, SAR, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Samaranayake
authors.forename: L P
authors.initials: LP
authors.lastname: Samaranayake
authors.forename: P C
authors.initials: PC
authors.lastname: Tsang
authors.forename: K H
authors.initials: KH
authors.lastname: Wong
authors.forename: K W
authors.initials: KW
authors.lastname: Yeung
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000188:drug therapy / Q000382:microbiology*; D000328:Adult; D000666:Amphotericin B / Q000627:therapeutic use; D000704:Analysis of Variance; D000935:Antifungal Agents / Q000627:therapeutic use*; D002176:Candida albicans / Q000145:classification* / Q000187:drug effects; D002180:Candidiasis, Oral / Q000188:drug therapy / Q000382:microbiology*; D002681:China; D015331:Cohort Studies; D004352:Drug Resistance, Microbial / Q000235:genetics; D005006:Ethnicity; D005260:Female; D015725:Fluconazole / Q000627:therapeutic use; D005500:Follow-Up Studies; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007654:Ketoconazole / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009960:Oropharynx / Q000382:microbiology; D010608:Pharyngeal Diseases / Q000382:microbiology; D012008:Recurrence
chemical_list: D000935:Antifungal Agents; D000666:Amphotericin B; D015725:Fluconazole; D007654:Ketoconazole