Low levels of antigenic variability in fluconazole-susceptible and -resistant Candida albicans isolates from human immunodeficiency virus-infected patients with oropharyngeal candidiasis

Three serial isolates of Candida albicans were obtained by direct swab or b y oral saline rinses from each of five human immunodeficiency virus-infecte d patients with recurrent oropharyngeal candidiasis. Genotyping techniques confirmed the presence of a persistent strain in multiple episodes from the same patient, which was different from the strains isolated from other pat ients. Fluconazole susceptibility was determined by both an agar dilution m ethod and the National Committee for Clinical Laboratory Standards macrobro th procedure. In four of these patients the strains developed fluconazole r esistance, and in one patient the strain remained susceptible. The differen t isolates were propagated as yeast cells on a synthetic medium, and their cell wall proteinaceous components were extracted by treatment with P-merca ptoethanol, Protein and mannoprotein components present in the extracts wer e analyzed by electrophoresis, immunoblotting, and lectin-blotting techniqu es. The analysis showed a similar composition, with only minor qualitative and quantitative differences in the polypeptidic and antigenic patterns ass ociated with the cell wall extracts from serial isolates from the same pati ent, as well as those from different strains isolated from different patien ts. Use of monospecific antibodies generated against two immunodominant ant igens during candidiasis (enolase and the 58-kDa fibrinogen-binding mannopr otein) demonstrated their expression in all isolates tested. Overall, the a ntigenic makeup of C. albicans strains remained constant during the course of infection and was not affected by development of fluconazole resistance. In contrast to previous reports, the low degree of antigenic variability o bserved in this study may be due to the fact that the isolates were obtaine d from a highly homogeneous population of patients and to the uniformity in techniques used for the isolation, storage, and culture of the different s trains, as well as extraction methodologies.