A NEW study has found that while concurrent bacteremia remains rare among children under 5 hospitalized with viral lower respiratory tract infections (VLRTIs), several clinical markers significantly increase the risk, especially in the youngest patients. The findings also reveal a notable post-pandemic shift in causative bacteria, with gram-negative pathogens such as Klebsiella spp. now leading.
In this retrospective study of 1,845 children admitted between January 2018 and December 2024 with PCR-confirmed influenza or respiratory syncytial virus (RSV) infections, only 1.9% were diagnosed with concurrent community-acquired bacteremia. However, the risk was far from evenly distributed. Infants aged 6 months or younger were over 14 times more likely to develop bacteremia compared to older peers. Additional independent risk factors included a C-reactive protein (CRP) level of 4 mg/dL or more, fever reaching 39 °C or higher, and the need for advanced respiratory support.
Multivariate logistic regression underscored the strength of these associations, with advanced respiratory support linked to an 8.3-fold increase in risk. Fever and elevated CRP were also strongly predictive, with adjusted odds ratios of 4.8 and 3.9, respectively.
Crucially, the study also found a pandemic-related shift in the bacteremia landscape. Prior to COVID-19, gram-positive organisms were more commonly identified in coinfections. In the post-pandemic period, however, Klebsiella spp. and other gram-negative bacteria have emerged as the predominant culprits, indicating a possible shift in both hospital and community epidemiology. This change has implications for empirical antibiotic strategies and pediatric infection control protocols.
The study underscores the importance of early identification of high-risk children in viral respiratory admissions, particularly those requiring intensive respiratory support or presenting with elevated inflammatory markers.
Reference:
Atay Ünal N et al. Prevalence and risk factors of concurrent bacteremia in children under 5 years of age hospitalized with viral lower respiratory tract infections. Eur J Clin Microbiol Infect Dis. 2025. doi: 10.1007/s10096-025-05211-8.
