Clinical value of repeat blood cultures in neonatal patients receiving antibiotic treatment

Objective Retrospective database study to determine the clinical usefulness of repeat blood cultures in antibiotic-treated neonates. Methods Data regarding blood culture indication and findings for patients admitted to a neonatal intensive care unit (NICU) over a 2-year period were obtained from the hospital database. Repeat blood culture was defined as culture performed <7 days from initial testing in a patient receiving antibiotic treatment. Results Repeat cultures made up 21.3% of all blood cultures originating in the NICU (500/2352 cultures; 338 initial positive cultures; 210 patients). The most common indications for repeat culture were follow-up of clinically well babies with previous positive culture findings and the development of new symptoms. The majority of culture findings were negative (60.2%), with 7.2% indicating the presence of a new pathogen. Cultures repeated on day 5 were significantly more likely to reveal a new pathogen than those repeated on days 1-4. Conclusions Repeat blood cultures in neonatal patients who have developed new symptoms >4 days after initial testing may be beneficial. The use of repeat blood culture is not recommended for any other indication.