Arterial blood culture to hasten the diagnosis of candidemia in critically ill patients.

Abstract

Dear Editor, Invasive candidiasis is a challenge for adults and pediatric ICU patients [1, 2]. Although serology (beta-D-glucan and Candida albicans germ tube antibody, CAGTA), when available, may help to distinguish between colonization and invasive candidiasis [3], positive blood cultures are required for a definite diagnosis of candidemia but Candida spp. are isolated from blood in 50 % of patients only. Because any delay in starting an appropriate antifungal therapy increases the overall mortality in patients with candidemia, a more rapid diagnosis is warranted. In a small group of patients with candidemia we observed that the time to positivity (TTP) for Candida spp. culture from arterial blood samples is considerably shorter than TTP of culture from peripheral veins. We retrospectively identified in our microbiological database 13 patients having blood culture drawn simultaneously from arterial and peripheral venous blood. The patients’ mean age was 59 ± 14 years and 10/13 patients were male. Risk factors associated with candidemia were previous antibiotic therapy (13/13), parenteral nutrition (13/13), ventilatory support (7/13), central venous catheter (CVC) (7/13), recent surgery (7/13), renal failure (4/13), and underlying cancer (3/13). Candidemia was considered CVC-related in 7/13 of patients and no case of deep-seated candidiasis was documented. C. albicans was isolated in 6/13 patients (46 %), Candida parapsilosis in 4/13, Candida glabrata in 2/13, and Candida tropicalis in 1/13. The median TTP was 25.35 h (22.23–32.87 interquartile range) for arterial blood cultures and 37.52 h (26.68–43.09 interquartile range) for peripheral vein blood cultures (p = 0.013), with a delta of 12 h (Wilcoxon matched-pairs signed rank test). The seven patients with CVCrelated candidemia and cared for in ICU also had blood cultures drawn from CVC in addition to the peripheral venous and arterial samples. In this subgroup TTP of arterial blood was significantly shorter with respect to peripheral vein (p = 0.016), whereas no difference was observed with respect to blood drawn from CVC (p = 0.469). The difference found between TTP of CVC versus