Adherence to HeLa cells, typing by killer toxins and susceptibility to antifungal agents of Candida dubliniensis strains

Abstract

The aim of this study was to evaluate the adherence capability to HeLa cells, the susceptibility to killer toxins and the in vitro susceptibility to antifungal agents (eTest  method -AB Biodisk, Solna, Sweden) of 9 Candida dubliniensis isolates recovered from HIV+ and AIDS patients. The adherence test was strongly positive for strain ATCC 777 and positive for all other strains. Typing by killer toxins revealed two different biotypes among the 9 isolates studied: 888 and 688. Only biotype 688 (ATCC 777) was susceptible to the K2 toxin. There was a significant inverse correlation between adherence and killer toxin susceptibility (r = -0.8525 -p = 0.0035). No strains presented resistance to fluconazole, itraconazole, ketoconazole, voriconazole, flucytosine or amphotericin-B. With the exception of ATCC 777, all the other isolates presented similar behavior. Descriptors: Candida; Cell adhesion; Acquired immunodeficiency syndrome; HIV.Resumo: O objetivo do presente trabalho foi avaliar o comportamento de cepas de Candida dubliniensis recuperadas de pacientes HIV+ e com AIDS por meio da pesquisa de capacidade de adesão a células HeLa, susceptibilidade a toxinas "Killer" e resistência in vitro a antifúngicos (eTest ® AB Biodisk, Solna, Suécia). O ensaio de adesão foi fortemente aderente para a amostra padrão ATCC 777, e aderente para os demais isolados. Os testes de tipagem das amostras frente às cepas-padrão produtoras de toxinas "Killer" mostraram dois biótipos diferentes dos 9 isolados estudados: 888 e 688. Somente o biótipo 688 (ATCC 777) de C. dubliniensis foi sensível à toxina K2. Houve correlação inversa significativa entre adesão e sensibilidade a toxinas "killer" (r = -0,8525 -p = 0,0035). Em relação à pesquisa de resistência a antifúngicos, as amostras de C. dubliniensis foram sensíveis ao fluconazol, itraconazol, cetoconazol, voriconazol, à flucitosina e anfotericina B. Com exceção da amostra ATCC 777, todas as demais mostraram comportamento similar.

Microbiological study of Candida sp in HIV-seropositive patients with a subclinical diagnosis of oral candidiasis

“…albicans was the predominant yeast in the present study. Similar results have been reported by Silva (26) and Oliveira (20) who isolated C. albicans as the predominant species from the oral cavity of patients infected with HIV, as well as C. tropicalis, C. krusei and C. glabrata.…”

Crystal violet staining to quantify Candida adhesion to epithelial cells

“…14 In vitro adherence studies of Candida on different surfaces are well established. 3,4,8,10,15 One quantification method is direct enumeration by microscopy, which has been used widely to determine the extent of yeast adhesion to epithelial cells. 16 Although this technique permits visualisation of the yeast cells adherent to individual epithelial cells, it is very time-consuming.…”