Review of single blood culture draws from hospitalized children resulting in contamination

Background: Blood cultures are a vital diagnostic tool in evaluating acutely ill pediatric patients with concerns for infection. Obtaining blood cultures in pediatric populations varies from the defined guidelines used in adults - notably the use of obtaining one blood culture per pediatric patient versus two blood cultures in adults. Some have argued that a single culture per patient (rather than two) increases hospital costs and length of stay due to the possibility of contaminated single cultures that may result in unnecessary antibiotic administration. This is a particular concern in the pediatric population, especially with regards to antibiotic stewardship.

Methods: An Institutional Research Ethics Board (IREB) approved retrospective chart review was performed at our local Children’s Hospital to analyze blood cultures’ rates of contamination. Blood cultures were obtained by single draws from pediatric patients from 10/1/2020 to 1/30/2021. Data was reviewed from blood cultures obtained from patients in the general pediatric hospital service, neonatal intensive care unit (NICU), pediatric intensive care unit (PICU), and pediatric emergency department. Results were compared for when a culture was obtained, when positive growth was recorded, and the final identification of organisms. Results were analyzed based on when a culture was obtained; if antibiotics were started at the time of the draw or changed based on culture identification. Based on organism identification, contamination rates were also obtained.

Results: Within our time period of nearly four months between fall and winter, 695 blood cultures were obtained within our Children’s Hospital. 60 blood cultures resulted in bacterial growth. Of the total blood cultures obtained, only five (0.72%) were found to be contaminated. All patients with positive cultures had been empirically treated with antibiotics. Patient therapy was adjusted appropriately due to culture results. When cultures resulted in positive growth Contaminant species included coagulase negative Staphylococcus and Micrococcus species.

Conclusion: Based on our retrospective chart review of single blood cultures from our pediatric population, only 0.72% of all the cultures were noted to be contaminated. The majority of blood cultures obtained resulted in no growth. Based on this chart review, one can argue that obtaining single blood cultures instead of multiple did not result in a significant amount of contamination that would have resulted in unnecessary antibiotic administration within our pediatric population. Given these findings, further studies examining the utility of using single blood culture draws versus multiple in hospitalized patients and analysis of department specific utilization of blood cultures would be of value.