Comparison of Manual and Automated Method for Speciation and Antifungal Susceptibility of Candida Species Causing Blood Stream Infection in Critically ill Patients

Abstract

Introduction: Globally, the incidence Blood Stream Infection (BSI) by Candida species is increasing. It is associated with high mortality rates especially in immunocompromised critically ill patients. The epidemiology has been shifted from Candida species to Non-albicans Candida (NAC) in recent decades. Speciation of Candida spp. can help to improve the outcome of patients as few Candida species are intrinsically resistant to antifungal agents. Aim: To identify the spectrum of Candida species causing BSI, study their sensitivity pattern to antifungal agents and comparison of conventional (germ tube test, Dalmau plate culture and Chromagar) and automated (Vitek-2) methods for the same. Materials and Methods: Blood specimens of the clinically suspected cases of septicaemic patients were cultured by BacT/ALERT before administration of antibiotics or antifungals during the study period of one and half year. The isolated Candida were identified to the species level along with antifungal susceptibility testing done by both conventional and automated (Vitek-2) methods. Statistical analysis was done using Chi-square test. Results: Of the total 100 Candida isolated, the most common Candida species was C.parapsilosis (26%), followed by C.tropicalis (23%), C.albicans (21%) and C.auris (15%). Total concordance between manual and Vitek-2 identification was 74%. Significant risk factors involved in patients with candidemia were malignancy, diabetes mellitus and chronic kidney disease. Antifungal susceptibility rate for amphotericin B, caspofungin, Fluconazole, Flucytosine, Micafungin and Voriconazole was 94%, 90.5%, 73.8%, 96.4%, 98.8% and 95.2%, respectively. Mortality rate was 45% due to sepsis and associated complications. Conclusion: Early isolation, speciation and antifungal susceptibility is the key for management of candidemia cases to get the better outcome as C.auris, the important multidrug resistant variant has caused a major epidemiologic shift in candidemia. Molecular studies are required for accurate speciation of Candida species like C. auris, C. haemulonii, C. famata, etc.

Keywords

• candida auris
• candida parapsilosis
• candidemia
• chromagar
• vitek-2