Özet:

ABSTRACT Objective: Blood culture (BC) is gold standard for diagnosis of fungemia. Contamination of BC is a major problem worldwide, since it may delay actual diagnosis. The aim of this study was to evaluate “contaminant” vials with a prolonged incubation (max 30 days) with antimicrobial supplemented media to observe any mycological growth. Materials and Methods: Routine BCs obtained patients of Balıkesir Atatürk City Hospital for a year period were included. Render BC System BC12-8 (Render Biotech Co. Ltd., Shenzhen, China) were used. Contaminated vials were re-incubated and conventionally inoculated weekly for four weeks total. In case of any growth, identifications were done by PhoenixTM 100 system (Becton Dickinson, MA, USA) with cornmeal tween 80 agar (RTA Laboratories, Kocaeli, Türkiye). Antifungal susceptibility testing was applied with CLSI disk diffusion method. Results: 3.9% (235 sets and additional 138 vials) of total 6047 BC sets (23.06% positive) were contaminated. Only one vial from central venous catheter showed fungal growth within the first week of conventional inoculation (>8th day of total incubation). The isolate was identified as Candida guilliermondii complex and susceptible to caspofungin. Latter set of this patient were positive for the same fungi in the 3rd day of incubation. Conclusion: International guidelines recommend <3% contamination rate. In this study, our single strain was isolated from catheter vial with prolonged incubation and following set was routinely positive for the same fungi. For optimal isolation at least 2 following sets were required and thus, prolonged incubation was not beneficial. It was found that strict following of the rule of “2 following sets" was enough for optimal isolation of fungemia agent.

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