Factors Predicting Blood Culture Positivity in Children With Enteric Fever

BACKGROUND: Blood culture, despite low sensitivity, is the gold standard for enteric fever diagnosis. Understanding predictors of blood culture positivity may help design strategies to optimize enteric fever diagnosis. METHODS: A cohort of 6760 children aged 0.5–15 years was followed for 3 years for enteric fever with blood cultures in an automated system, for fevers >3 days. Factors affecting test positivity in fevers and participant-level predictors for culture refusals were analyzed using regression models. RESULTS: Overall, 6097 suspected typhoid/paratyphoid fever (STF) episodes were reported, of which 5703 (93.5%) STFs had sampling for blood cultures, with 394 (6.5%) refusals. Salmonella enterica serovar Typhi/Paratyphi positivity was culture-confirmed in 3.8% (218/5703) of STF episodes. Older children (odds ratio [OR], 1.96 [95% CI, 1.39–2.77]), larger blood volume inoculated (OR, 2.82 [95% CI, 1.71–4.66]), higher temperatures during fever (OR, 3.77 [95% CI, 2.89–4.91]), and fevers diagnosed as suspected typhoid or acute undifferentiated fever (OR, 6.06 [95% CI, 3.11–11.78]) had a higher probability of culture positivity. Antibiotics before culture did not decrease culture positivity. Blood culture refusals were higher for children from wealthier households or with milder illness. CONCLUSIONS: Performing blood cultures in older children with fever, especially those fevers with toxic presentation and increasing blood volume for inoculation are strategies to improve enteric fever detection in surveillance settings.