A simple blood test may help detect serious bacterial infections (SBIs) like urinary tract infections and blood stream infections in young infants who come to the emergency department (ED) with fevers that have no clear cause. The researchers used a novel test with the marker procalcitonin, recently approved by the U.S. Food and Drug Administration (FDA), in 234 feverish babies under three months of age, of whom 18 percent had definite or possible SBIs confirmed by independent clinical criteria.

The results showed that procalcitonin not only detected all cases of SBIs in feverous infants but proved sensitive enough to establish a threshold value that would identify infants at low risk for serious infections. Indeed, its overall performance as a single clinical marker of infection approached that of current strategies that involve a variety of laboratory tests and clinical evaluations.

Because clinicians cannot reliably determine which children with fever have more serious infections, many babies end up undergoing extensive evaluations. Routine evaluation of infants less than three months of age includes blood tests, urine tests, and often a lumbar puncture for spinal fluid, followed by treatment in the hospital with antibiotics. Prompted by the inefficiency of current fever management in young infants, the researchers have sought a rapid diagnostic test that will determine which children have serious infections at the first visit to the ED.

The high sensitivity of the new procalcitonin test has allowed the scientists to establish realistic cut-off values to help guide clinicians in identifying children who are at low risk for SBIs. The researchers are now looking to do a multi-center study to evaluate the use of procalcitonin on a larger scale.