Higher nursing care level is associated with higher incidence of blood culture contamination in the emergency department: A case–control study

BACKGROUND: Blood culture is critical in treating infectious diseases. This leads to unnecessary intervention, inappropriate antibiotic use, and excess cost. Few studies have tackled patient factors that could possibly affect contamination rates. This study aimed to explore the association between patients' nursing care levels and blood culture contamination. METHODS: This is a single‐centered, retrospective, case–control study of adult patients whose blood culture specimens were taken in the emergency department between April 2018 and July 2019. The study was conducted in an acute care community hospital in Japan. The case group included patients with false‐positive blood culture results with contamination; the control group included patients with true‐positive or true‐negative blood culture results without contamination. We randomly selected two control patients per case. Patients' age, gender, nursing care level, ambulance use, housing status, Glasgow Coma Scale, hospital arrival time, and puncture sites were obtained from the patients' medical charts. RESULTS: Of the 5130 patients, 686 patients got positive blood culture results. Of the 686 patients, 35 patients were included in the case group, and 70 were randomly selected from the noncontaminated group and included in the control. In multivariate analysis, patients with contaminated blood cultures had a higher nursing care level (adjusted odds ratio: 8.50; 95% confidence interval: 1.65–43.7; p = 0.01). CONCLUSIONS: A higher nursing care level is associated with a higher incidence of blood culture contamination in the emergency department. Careful and appropriate procedures are required for patients with a higher nursing care level.