Invasive candidiasis by Candida non-albicans and non-auris in a fourth level hospital in Colombia: epidemiology, antifungal susceptibility and genetic diversity

Objectives. Increasingly common and associated with healthcare settings, Candida infections are very important, since some species of this genus can develop antifungal resistance. We aimed to study the epidemiology of invasive infections caused by Candida non-albicans and non-auris in a fourth level hospital in Bogota, Colombia, and to determine the antifungal susceptibility profile and genetic diversity of the etiological agents. Materials and Methods. All non-albicans and non-auris Candida isolates that were reported to be causing invasive infections over 18 months were studied. The isolates were identified by conventional routine methods, including Vitek and MALDITOF. Patients affected by these yeasts had epidemiological data on sex, age, treatment and outcome. In addition, the antifungal susceptibility of the isolates to nine antifungals was determined using YeastOne broth microdilution and the ribosomal DNA was sequenced. Statistical analyses were carried out to correlate epidemiological variables and to establish differences in antifungal susceptibility between species, per antifungal drug. Results. In the studied period, 68 non-albicans and non-auris Candida isolates, recovered from 58 patients and representing 48.5% of invasive candidiasis, were identified. From the species, 29 (42.6%) were Candida parapsilosis, 18 (26.5%) Candida glabrata, 17 (25%) Candida tropicalis, and 4 (5,9%) Candida dubliniensis. One isolate of Candida guilliermondii was reported by the hospital but not included in the study due to mold contamination. Isolates were recovered mainly from blood (50%) and other sterile sites. From the patients, the majority were men (53.4%). Patient’s age ranged between 18 days and 93 years old (average 63.1 years). Most patients were hospitalized in the ICU (70.7%) and treated with fluconazole (36.2%) followed by caspofungin (32.8%). A third of the patients did not receive any antifungal treatment. General mortality was 46.6%. However, patients affected by C. glabrata were found to have a higher mortality risk (62.5%) than patients affected by other species. Higher mortality was also associated with an older age. Antifungal susceptibility showed that C. parapsilosis isolates were the less susceptible to echinocandins, compared to isolates of other species, while C. glabrata isolates were the less susceptible to azoles followed by C. tropicalis. Amphotericin B and flucytosine susceptibility did not differ among species. From the isolates, one of C. glabrata was resistant to caspofungin, four of C. parapsilosis were resistant to fluconazole, two of C. tropicalis were resistant to both voriconazole and fluconazole and three others of C. tropicalis were resistant to flucytosine. Generally, low genetic diversity was identified among the isolates. Conclusions. This study provides important epidemiological data for the local and global surveillance of emerging Candida species, highlighting the importance of monitoring the rise of infrequent species, such as C. dubliniensis and C. guilliermondii, and their clinical impact. Our study highlights as well the emergence of acquired resistance, which could significantly increase morbidity and mortality rates, together with the clonal dispersal of some species.