[Susceptibility to nystatin of oral Candida isolates and its correlation with the response to treatment].

Introduction: oropharyngeal candidiasis is an early marker of progression to AIDS in H1V-positive patients and an indicator of non-adherence of treatment or possible failure in patients undergoing anti-retroviral therapy.

Objective: to determine the in vitro susceptibility to nystatin in Candida strains isolated from the oral cavity of HIV-positive patients, and to correlate the results with the response to treatment.

Methods: a study of in vitro susceptibility to nystatin was conducted in 104 oral isolates from 97 HIV/AIDS patients, who participated as volunteers in a clinical trial to evaluate the response to four antifungal drugs. Fifty-eight of the 104 isolates were obtained before starting treatment and the remaining 46 at the end of therapy. Broth microdilution method was performed according to the document M27-A3 of the Clinical and Laboratory Standards Institute.

Results: one hundred percent of the strains were susceptible to nystatin, with minimum inhibitory concentration (MIC) values of <16 microg/mL, regardless of the time of isolation and of the drug administered to patients. In the group of patients treated with nystatin, the MIC80 ranges (1-2 microg/mL), geometric mean and cumulative values of the drug against Candida albicans isolates before starting treatment were similar to those obtained against strains recovered at the end. Among the identified species, C. lusitaniae reached the highest absolute MIC value (4 microg/mL).

Conclusions: the correlation between the clinical evolution and the results of in vitro susceptibility tests was good in patients with a favorable outcome; however, it did not allow predicting possible treatment failure.