The following is a summary of “Recovery of pathogens with the implementation of a weight-based algorithm for pediatric blood cultures: an observational intervention study,” published in the July 2024 issue of Pediatrics by Mortensen et al.

Increasing the volume of blood submitted for culture in children is a critical strategy for enhancing the recovery of pathogenic bacteria and yeast from blood cultures while accurately distinguishing between true pathogens and contaminants. This study primarily aimed to evaluate whether implementing a weight-based algorithm for determining the volume of blood submitted for microbiological analysis would lead to an increased recovery rate of pathogens. Additionally, secondary objectives included assessing the impact of the algorithm on the contamination rate of blood cultures, investigating whether the presence of pathogens occurs more frequently in multiple culture bottles as opposed to single bottles, and providing a comprehensive clinical validation of true blood culture positivity by examining microbiological findings for both pathogens and contaminants.

A pre-post intervention study design was utilized, comparing positivity and contamination rates before and after the implementation of the algorithm. A total of 5,327 blood cultures were analyzed, revealing 186 instances of growth, comprising 123 true positives and 63 contaminants. Following the intervention, the rate of true positive blood cultures exhibited a statistically significant increase from 1.6% (42 out of 2,553) to 2.9% (81 out of 2,774, p = 0.002). Notably, the contamination rate did not show a significant change, with pre-intervention rates at 1.4% (35 out of 2,553) compared to 1.0% (28 out of 2,774, p = 0.222) post-intervention; however, the proportion of contaminated cultures among all positive cultures decreased from 45% (35 out of 77) pre-intervention to 26% (28 out of 109, p = 0.005) post-intervention. Furthermore, a microorganism that grew in a single bottle was classified as a contaminant in 35% of cases (8 out of 23), whereas those identified in at least two bottles were deemed contaminants in only 2% of cases (1 out of 49, p < 0.001). Based on established classification criteria focusing primarily on microbial identity, 14% (17 out of 123) of the identified pathogens would have been incorrectly classified as contaminants.

In conclusion, the implementation of a weight-based algorithm for determining the volume and number of blood cultures in children significantly enhances pathogen recovery rates while concurrently improving the accuracy of distinguishing true pathogens from contaminants. This approach not only optimizes clinical outcomes but also underscores the importance of methodological advancements in microbiological practices.

Source: bmcpediatr.biomedcentral.com/articles/10.1186/s12887-024-04930-9