Molecular typing of Candida albicans isolates from Lebanese hospitals in correlation to: Phenotypic identification, epidemiology, antifungal resistance profile, and biofilm formation. (c2013)

Abstract

Candida species are the most common opportunistic pathogens in debilitated or immunocompromised hosts and cause systemic candidiasis, which has high rates of morbidity and mortality. Most of these infections are nosocomial and raise the issue of hospital hygiene. As such the identification and subtyping of Candida species is epidemiologically important for recognizing outbreaks of infection, detecting cross-transmission, determining the source of the infection, and recognizing particularly virulent strains, or detecting the emergence of drug resistant strains. In this study our objective is to compare Candida albicans hospital identification rates with conventional laboratory employed methods such as API, CHROMagar and germ tube formation and a more reliable molecular method such as ITS typing. Furthermore our aim was to assess biofilm-forming capacities with drug resistance profiles and correlate them with MLST typing of isolates. ITS typing was performed for 75 isolates and the misidentification rate for each method is considered significant: 9.3% for API and CHROMagar, and 17.3% for the hospital. Moreover, antifungal susceptibility testing was performed for 4 antifungal drugs encompassing different antifungal classes, and antifungal resistance to 3 and to the 4 drugs was found to occur amongst 25% of isolates tested which was unexpected and raises serious questions concerning the methods of treatment. Interestingly some strains with significant biofilm forming capabilities correlated well with strains that were multidrug resistant and such strains grouped closely together in a neighbor-joining tree generated by MLST typing indicating phylogenetic relatedness or strain microevolution or recurrent infection. In conclusion, this pilot study gives insight about many aspect of Candida albicans isolates circulating in hospitals, unfortunately the small sample size and lack of information about patient history, preclude any firm conclusions.