True Bacteremia or Contamination? Predictive Factors for Contamination in Blood Cultures Obtained in the Pediatric Emergency Room

Abstract

Aim:This study aimed to investigate the factors affecting bacteremia and contamination in patients admitted to the pediatric emergency room.Materials and Methods:This retrospective study focused on patients 1 month to 18 years of age who underwent blood culture tests at the University of Health Sciences Turkey, İzmir Tepecik Training and Research Hospital from 2013 to 2017. We performed a history and physical examination and noted the presence of fever, pediatric assessment triangle findings on admission, laboratory characteristics, and outcomes associated with true bacteremia and contamination. Patients with no growth in blood culture were excluded from the study. Statistical analysis consisted of the χ2 test, Mann-Whitney U test, receiver operating characteristic analysis, calculations of sensitivity and specificity, and the multivariable logistic regression model.Results:Blood culture growth was detected in 514 (12.2%) of 4,200 culture samples assessed during the study period. A total of 449 patients were included in the study. Culture results of 165 patients (36.7%) were defined as indicative of true bacteremia and those of 284 patients (63.2%) as contamination. Patients with true bacteremia were more likely to have fever (81.4% vs. 64.5%, p<0.001), underlying risk factors (61.9% vs. 23.5%, p<0.001), and longer hospital stays (11 days vs. 7 days, p<0.001). Normal pediatric assessment findings on admission were observed between the contamination group and the true bacteremia group (p<0.001). Patients with bacteremia had higher white blood cell counts (13,900 vs. 11,300, p<0.001), C-reactive protein (CRP) (38.5 vs. 6.3, p<0.001), and procalcitonin (1.04 vs. 0.18, p<0.001). The area under the curve was 0.712 for the CRP level. The cut-off value for CRP (mg/L) was 11.75 (sensitivity, 72.6%; specificity, 62.4%). In the multivariable logistic regression analysis, fever on admission [odds ratio (OR), 2.4; 95% confidence interval (CI), 1,037-5,524; p=0.041], male sex (OR, 2.2; 95% CI, 1,066-4,716; p=0.033), and CRP (OR, 1.0; 95% CI, 1,003-1,017; p=0.005) were significantly associated with true bacteremia.Conclusion:The presence of fever on admission and high CRP levels may be good indicators of which patients require BCs.

Keywords

• bacteremia
• blood culture
• contaminant
• pediatrics