Background: Bloodstream infections (BSI) represent a common cause of sepsis and mortality in children. Blood culture (BC) is the gold standard for diagnosis of BSI. The low sensitivity of BC in the pediatric population is usually due to the small volume of blood used for inoculation and to the antibiotics used before sampling. Here, we explore the ways to effectively reduce antibiotic activity to maximize the chances of pathogen recovery, and to enhance the growth of microorganisms in lower blood volume and bacterial counts.
Methods: The recovery of common pathogens causing blood stream infections was analyzed after exposure to cefo-perazone/sulbactam, vancomycin, and caspofung by using resin-containing or not BacT/Alert PF Plus and BD FX400 peds plus pediatric bottles. The microbial growth in the resin-containing bottles was assessed using 0.5 colony-forming units (CFU) bacterial inoculum to mimic the bacteremia/fungemia condition. The usefulness of a diagnosis to confirm or exclude BSI was evaluated by lower than recommended blood culture sampling (102 CFU/mL, 0.3 mL).
Results: Staphylococcus aureus (S. aureus), and Candida glabrata (C. glabrata) were recovered from 100% of two types of resin-containing bottles in the presence of a sufficient antibiotic dose, while Escherichia coli (E. coli) was not restored to 100% in BD FX400 peds plus pediatric bottles. The shorter TTD for S. aureus, C. glabrata, and E. coli were observed in antibiotic-containing BacT/Alert PF Plus bottles. Both the PF Plus and BD resin test bottles showed consistently good TTD performances to Gram-negative, Gram-positive, and yeast species in low inoculum levels, with the exception of S. aureus. The lower volume of blood inoculated into culture bottles hardly affected the growth of most bacteria, but optimized PF Plus resin-bottles accelerated the detection of infectious agents, especially S. aureus, Streptococcus pneumoniae, and C. glabrata.
Conclusions: It is possible to enhance recovery from antibiotic-containing pediatric bottles and shorten TTD for the identification of pathogens by using the BacT/Alert blood culture system combination with new resin-containing media.