Detection of azole resistance and ERG11 point mutations in Candida albicans isolates from tertiary hospitals in the Philippines

Candida albicans is commonly isolated from nosocomial fungal infections, and controlling these infections depends on the immune status of the patient, gravity of the infection, and the choice of the administered antifungal drug. Increasing worldwide reports of strains that are resistant to the azole drugs, which are commonly used for treatment of diseases caused by C. albicans, warrant the conduct of drug susceptibility testing of clinical isolates, which is not routinely done in the Philippines. Twenty-six local C. albicans clinical isolates were tested for their susceptibility to the azole drugs fluconazole and voriconazole using the standard disc agar diffusion method. Likewise, the ERG11 gene coding for lanosterol-14-α-demethylase involved in ergosterol synthesis, which is the target of the azole drugs, was studied for the occurrence of point mutations. Results of the assay showed phenotypic resistance patterns to both drugs in 19 isolates (or 73.08%). Six isolates were determined susceptible to both drugs, while one isolate was susceptible-dose dependent also to both antifungals. Detection of ERG11 mutations following nucleotide sequencing revealed the presence of point mutations A369C, T462C and C558T. Mutations A369C and T462C have been identified as possible factors associated with the resistance to azole agents in previous studies. The results imply that it is imperative to continuously perform susceptibility testing on clinical isolates of C. albicans for effective treatment management and for the surveillance of antifungal resistance in the organism. © Beijing Academy of Agriculture and Forestry Sciences