Evaluation of Mannose-binding Protein as a Predictor of Serious Bacterial Illness in Febrile Infants 784

Abstract

Mannose-binding protein (MBP) is an acute phase reactant important in innate host defence. It recognizes and binds pathogens, promotes their opsonization and phagocytosis and activates complement. Low MBP levels are associated with allelic variants that are unable to activate complement. It is hypothesized that low levels of MBP are associated with serious and/or recurrent infection. To determine whether MBP level is a predictor of serious bacterial illness and if low levels of MBP are associated with increased risk of bacterial infection, we measured MBP in infants <3 years old (n=570) who presented to the Children's Hospital Emergency Department for evaluation of fever. To enhance the number of patients with serious bacterial infection (n= 92), febrile infants with positive cultures were included selectively by using stored discarded blood samples. Temperature, CBC, present diagnosis and history of previous positive culture were recorded for each patient. C-reactive protein (CRP) and interleukin-6 (IL-6) were measured selectively. MBP level was compared in febrile infants and age-matched controls. MBP level was not significantly different between febrile infants and controls or between infants with current or previous serious bacterial illness and those with presumed viral illness with or without otitis media. MBP level was not correlated with IL-6 or CRP. The percent of patients with MBP levels <100, 500, and 1000 ng/ml did not differ between febrile patients with and without serious bacterial illness. We conclude that a single MBP level is not a predictor for bacterial illness and that febrile infants with low MBP levels are not universally at significant risk for serious bacterial illness.Sponsored by Bristol-Myers Squibb.