Étude biochimique et sérotypique de 40 souches de Cryptococcus neoformans isolées de patients VIH+ à Abidjan (Côte-d'Ivoire)

Abstract

Objective The prevalence of the cryptococcosis is high in Côte-d'Ivoire but the distribution of the varieties and the serological types of Cryptococcus neoformans have not previously been studied. The objective of this work was to determine the distribution of the serotypes and the biochemical characters of strains isolated in Côte-d'Ivoire. Methods Forty strains of C. neoformans isolated from the cerebrospinal fluid of Ivorian HIV-seropositive patients were studied. The isolates were cultivated on Sabouraud glucose agar with chloramphenicol and on Pal's modified-medium and incubated at 37 °C for 48 hours. The biochemical characters were studied using the ID 32C gallery and the APIZYM gallery (bioMérieux ®, Marcy-l'Etoile, France), the production of phenol oxidase and urease and the reduction of nitrate. Serological typing was performed by agglutination (Crypto Check ®, Iatron Laboratories Inc., Tokyo, Japan). Results The study revealed that 100% of the strains belonged to C. neoformans var. neoformans, 95% to serotype A and 5% to serotype D. The auxanogram test revealed 6 profiles of which 3 were the most frequently represented and included 79% of the strains. Five specific substrates were not assimilated by any strain. The enzymatic profiles performed with the APIZYM gallery including 19 substrates was able to reveal the non expression of 9 enzymes and varying degrees of expression of the 10 other enzymes. Conclusion C. neoformans var. neoformans serotype A was the main agent responsible for cryptococcal meningitis in HIV-serpositive patients in Abidjan (Côte-d'Ivoire).