Other pathogens account for 28% of invasive bacterial infections in febrile young infants

A multicenter retrospective study in The Pediatric Infectious Disease Journal examined invasive bacterial infections (IBIs) in 375 febrile infants aged ≤90 days at 12 Spanish pediatric emergency departments between 2008 and 2022. Researchers characterized infections caused by pathogens other than Escherichia coli and Streptococcus agalactiae. Adverse outcomes included death, inotropic or respiratory support, acute complications, or sequelae.

Other pathogens caused 106 infections (28.3%). The most frequent were Staphylococcus aureus (30 cases; 8.0% of all IBIs), Streptococcus pneumoniae (15; 4.0%) and Enterococcus faecalis (14; 3.7%). Among infections caused by other pathogens, 65.1% presented as isolated bacteremia, 18.9% as bacteremic urinary tract infection and 12.3% as meningitis. Of infants with meningitis in this group, 46.2% had a concomitant urinary tract infection.

S. aureus was more frequent in younger infants, while S. pneumoniae accounted for 8.6% of IBIs at ages 61–90 days. Listeria monocytogenes caused 1.3% of all IBIs, with only one case identified in the last decade. Adverse outcomes occurred in 7.5% of the other-pathogen group versus 8.6% of the E. coli/S. agalactiae group; the reported absolute risk difference was −1.0 percentage points (95% CI, −7.1 to 5.0).

The findings highlight age-dependent pathogen patterns in young infants with IBI. Meningitis was associated with more adverse outcomes, but the retrospective design and Spanish emergency-department setting limit generalizability. The outcome comparison does not establish equivalence between pathogen groups.