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Factors Predicting Blood Culture Positivity in Children With Enteric Fever
Manikandan Srinivasan1, Kulandaipalayam Natarajan Sindhu1, Karthikeyan Ramanujam1
1Division of Gastrointestinal Sciences, Wellcome Trust Research Laboratory, Christian Medical College, Vellore, India.
Insights
Blood culture positivity for enteric fever is higher in older children, fevers with toxic presentation, and larger blood volumes. These factors can optimize diagnosis in surveillance settings.
Area of Science:
- Pediatrics
- Infectious Diseases
- Clinical Microbiology
Background:
- Blood culture is the gold standard for diagnosing enteric fever, but its sensitivity is low.
- Understanding factors that predict blood culture positivity is crucial for improving diagnostic strategies.
Purpose of the Study:
- To identify predictors of blood culture positivity in children with suspected enteric fever.
- To analyze participant-level factors associated with blood culture refusals.
Main Methods:
- A cohort of 6760 children (0.5-15 years) was followed for 3 years.
- Blood cultures were performed for fevers lasting >3 days using an automated system.
- Regression models were used to analyze factors affecting test positivity and culture refusals.
Main Results:
- Of 6097 suspected enteric fever episodes, 5703 had blood cultures, with a 3.8% positivity rate for Salmonella Typhi/Paratyphi.
- Older children, larger blood volumes, higher fever temperatures, and suspected typhoid/acute undifferentiated fever increased culture positivity.
- Antibiotics before culture did not reduce positivity; refusals were higher in wealthier households or milder illness.
Conclusions:
- Performing blood cultures in older children with fever, especially those with toxic presentation, can improve enteric fever detection.
- Increasing blood volume for inoculation is a strategy to enhance diagnostic yield in surveillance settings.
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.
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