PM2042: Utility of Follow-up Pediatric Blood Cultures

Background: Adult literature has found repeat blood cultures in bacteremic patients offer little utility unless specific organisms (e.g. Staphylococcus aureus) are present. There is little data in pediatrics. Unnecessary blood cultures result in increased patient discomfort, increased contamination rates, and may lead to unnecessary antibiotic therapy. Our objective was to identify which subset of pediatric patients are at risk for persistent bloodstream infections to identify when follow-up blood cultures have clinical utility.

Methods: We conducted a retrospective cross-sectional study of children from August 1, 2016 through December 31, 2021 who had a positive blood culture in our hospital. Initial collected data included the age of the patient, location of the blood draw, organism recovered, and whether subsequent blood cultures were positive suggesting persistent infection, defined as positive blood cultures greater than 48 hours after index case of bloodstream infection. Multivariate analysis was conducted with logistic regression.

Results: There were 817 cases of index positive blood cultures during the study period. Of these, 412 (50.4%) had a repeat blood culture drawn >48 hours after the initial culture and 71 (8.7%) had persistent infection. 417 (51.0%) of the initial cultures were from the inpatient setting, while 333 (40.8%) were drawn in the emergency department. Having Candida sp. (8/15, 53%,) or S. aureus (32/128, 25%) blood stream infection was associated with persistent infection compared with other organisms such as coagulase-negative Staphylococcus (4.9%, 9/182) (p < 0.001). The positivity frequency for repeat blood cultures after Gram negative bacteremia was 17/230 (7.8%). Patients from birth to 12 weeks, 12 weeks to 24 months, and from 24 months to 18 years had a 24/263 (9.1%), 8/161 (5.0%), and 39/393 (8.7%) incidence of persistent infection, respectively (p = 0.163). The pediatric intensive care setting was associated with the highest frequency of persistent bloodstream infection at 15/84 (18.0%) while initial blood cultures drawn in the emergency department setting were less likely to be positive >48 hours later (16/333, 4.8%) (p < 0.0001). For anaerobic organisms (n=39) and all species of streptococcus (n=134) there were no repeat positive blood cultures.

Conclusion: Similar to what is reported in adults, repeat blood cultures have the most utility for children with candidemia and S.aureus bacteremia. There is no evidence to support repeat blood cultures after bacteremia with anaerobes, and any streptococcal species. The incidence of persistent bloodstream infection is higher in the pediatric intensive care unit when compared to average rates. There is no evidence that age or location of blood draw significantly contributes to the incidence of persistent infections. Currently we are performing a detailed chart review to assess clinical risk factors that may determine the need for repeat blood cultures in patients where rates are typically low to avoid unnecessary blood cultures in children.