Prevalence and predictors of residual antibiotics in children’s blood in community settings in Tanzania

Introduction Children account for a significant proportion of antibiotic consumption in low- and middle-income countries, with the overuse of antibiotics occurring in both formal and informal health sectors. This study assessed the prevalence and predictors of residual antibiotics in children’s blood in Mbeya and Morogoro regions of Tanzania. Methods The cross-sectional community-based survey used two-stage cluster sampling to include 1,699 children under 15 years of age. For each child, information on recent illness, healthcare-seeking behavior, and the use of antibiotics, as well as a dried blood spot (DBS) sample, were collected. The samples underwent tandem mass spectrometry analysis to quantify the concentrations of 15 common antibiotics. Associations between survey variables and presence of residual antibiotics were assessed using mixed-effects logistic regression. Results The overall prevalence of residual antibiotics in the blood samples was 17.4% (95% CI: 15.6– 19.2), with the highest prevalence among under-five children. The most frequently detected antibiotics were trimethoprim (8.5%), sulfamethoxazole (6.0%), metronidazole (3.6%) and amoxicillin (2.5%). The strongest predictors of residual antibiotics in the blood were observed presence of antibiotics at home (aOR=2.9; 95% CI: 2.0–4.1) and reported consumption of antibiotics in the last two weeks (aOR=2.5; 95% CI: 1.6–3.9). However, half of the children who had residual antibiotics in their blood had no reported history of illness or taking antibiotics in the last two weeks, and antibiotics were not found in the home. Conclusion The study demonstrated high prevalence of antibiotic exposure among children in Tanzanian communities, albeit likely still underestimated, especially for compounds with short half-lives. A significant proportion of antibiotic exposure was unexplained and may be due to unreported self-medication or environmental pathways. Incorporating biomonitoring into surveillance strategies can help to better understand exposure patterns and design antibiotic stewardship interventions. Key messages What is already known about this topic? Children are major consumers of antibiotics in low- and middle-income countries, worsening the emergence of antibiotic resistance. There is high reported use of prescribed and non-prescribed antibiotics in Tanzania, but no reliable data about the prevalence of antibiotic exposure in the pediatric population. What are the new findings? The prevalence of residual antibiotics in children’s blood is high, albeit still likely under-estimated, especially for compounds with short half-lives. Children are often exposed to several antibiotics concurrently, many with their exposure unexplained by illness history or reported consumption. Recommendations for policy Integrating objective quantification of antibiotic exposure into monitoring and surveillance strategies can help to better understand exposure patterns and design stewardship interventions.