Identification of Candida isolated from blood cultures at species level and determination of their antifungal susceptibilities

Bloodstream infections caused by Candida have high morbidity and mortality. Accurate and rapid identification of Candida at the species level and determination of their antifungal susceptibility allows accurate and early treatment. In our study, we aimed to identify Candida isolates isolated from blood culture samples taken from patients admitted to Van YYÜ Dursun Odabaş Medical Center at the species level using traditional methods, automated systems and PCR methods, and to determine their antifungal resistance profiles using the standard methods of broth microdilution, gradient test and disk diffusion methods. 63 Candida isolates isolated from blood culture samples taken from patients admitted to Van YYÜ Dursun Odabaş Medical Center were included in the study. Identification of isolates was carried out using traditional methods such as germ tube and CHROMagar Candida (RTA, Turkey); It was performed with automated systems BD Phoenix M50 (Becton Dickonson, USA) and MALDI-TOF MS (Biomeriux, France) and with molecular methods multiplex PCR. For antifungal susceptibility, Gradient Test and Disk Diffusion methods were compared with the Broth Microdilution Method, which is recommended as a reference method. A total of 32 strains were positive in the germ tube test and were identified as C. albicans. False germ tube positivity was found in eight isolates and the other isolates were detected as germ tube negative and determined as non-albicans Candida. While 59 commonly seen strains in CHROMagar Candida medium were identified at the species level, four strains could not be identified at the species level, indicating Candida spp. It was reported as. A strain detected as C. albicans by multiplex PCR was named C. tropicalis with CHROMagar Candida medium. In the multiplex PCR method using species-specific primers, 32 strains were identified as C. albicans, 11 strains as C. parapsilosis, eight strains as C. tropicalis, seven strains as C. glabrata, three strains as C. kefyr, one strain as C. lusitaniae and one strain as C. krusei. BD Phoenix M50 automated system identified 61 of 63 strains compatible with multiplex PCR; A strain identified as C. tropicalis by the multiplex PCR method was identified as S. cereviseae by BD Phoenix M50, and a strain identified as C. albicans was identified as C. parapsilosis. The MALDI-TOF MS automated system identified 60 of 63 strains compatible with multiplex PCR; He identified three separate strains detected as C. albicans by multiplex PCR method as C.kefyr, C. tropicalis and C. lusitaniae. According to antifungal sensitivity tests; According to the broth microdilution method, all isolates with known breakpoints according to EUCAST were found to be sensitive to amphotericin B. One C. albicans, two C. parapsilosis and all C. glabrata isolates were moderately susceptible to fluconazole; the remaining isolates were found to be susceptible. All isolates except one resistant C. albicans strain were susceptible to voriconazole. 15 of the C. albicans isolates and six of the C. parapsilosis isolates were found to be resistant to micafungin, and all C. glabrata strains were sensitive. Zone diameters found for amphotericin B in the disc diffusion method varied between 10-20 mm. The agreement between disk diffusion and broth microdilution methods for voriconazole was found to be 90.9% for C. parapsilosis and 100% for C. albicans and C. tropicalis. For fluconazole, the agreement between the two methods was 81.8% for C. parapsilosis, 96.8% for C. albicans, 100% for C. tropicalis, and 42.8% for C. glabrata.The gradient test was found to be 100% compatible with the broth microdilution method for amphotericin B. For fluconazole, the agreement between the two methods was found to be 56% for C. albicans, 36% for C. parapsilosis, 75% for C. tropicalis and 100% for C. glabrata. For voriconazole, the agreement between the two methods was found to be 25% for C. albicans, 73% for C. parapsilosis, and 62% for C. tropicalis. The gradient test was sensitive to micafungin in all isolates that could be evaluated. For micafungin, the agreement between the two methods was found to be 50% for C. albicans, 45% for C. parapsilosis and 100% for C. glabrata. Candida species have been identified with a high rate of accuracy by traditional methods and automated systems; Compared to the multiplex PCR method, the highest compatibility rate was obtained with the BD Phoenix automated system. This was followed by the MALDI-TOF MS automated system. The disc diffusion method has been identified as an alternative method to broth microdilution in detecting antifungal resistance. Gradient testing method was found to be safe for amphotericin B.