The clinical characteristics and risk factors of mixed Candida/bacterial bloodstream infections

Objective To investigate the clinical characteristics and associated risk factors for patients with mixed Candida/bacterial bloodstream infections (BSIs). Methods A retrospective study was conducted in the Second Affiliated hHospital of Zhejiang University School of Medicine from February 2012 to June 2015. The clinical data of cases was collected, and the clinical characteristics, the microbiology data and outcomes in patients with mixed Candida/bacterial BSIs confirmed by blood culture were compared with those with candidaemia. A Logistic regression analysis was performed to investigate the independent risk factors. Results A total of 136 candidaemia cases were analyzed including 40 cases (29.4%) of mixed Candida/bacterial BSIs and 96 cases of candidaemia. Among the 136 candidas strains, the proportion of non-albicans exceeded the albicans (50.7% vs 49.3%), although the later was still the predominant one. There was no significant difference in the distribution of candidas strains between patients with mixed Candida/bacterial BSIs and patients with candidaemia. In patients with mixed Candida/bacterial BSIs, 25 strains (61.0%) of gram-positive cocci and 16 strains (39.0%) of gram-negative bacilli were isolated. Compared with patients with candidaemia, patients with mixed Candida/bacterial BSIs needed longer period of antifungal therapy [12.0 (4.0-25.0)days vs 7.0 (3.0-13.5) days, P=0.027], but the crude 30-day and 90-day mortality did not differ between the two groups (40.0% vs 32.3%; 45.0% vs 36.5%; both P>0.05). Univariate analysis revealed that the prior hospital stay, ICU admission at the onset of candidaemia, blood transfusion, human albumin infusion, mechanical ventilation, linezolid use and high SOFA score were related with the occurrence of mixed Candida/bacterial BSIs (all P<0.05). Multivariate analysis showed that only high SOFA score was the independent risk factor (P=0.003). Conclusions Gram-positive cocci were the predominant species in mixed Candida/bacterial BSIs. Compared with candidaemia, mixed Candida/bacterial BSIs needs a longer ICU stay, a longer hospital stay, and a prolonged antifungal therapy. High SOFA score is the independent risk factor for mixed Candida/bacterial BSIs. Key words: Candidaemia; Bacterial bloodstream; Mixed infection; Clinical characteristics; Strains distribution; Antifungal susceptibility; Risk factors; Clinical outcome