Surrogate markers superior for detecting bacterial infection

C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), and absolute neutrophil count (ANC) have similar diagnostic properties and are superior to clinical evaluation in detecting serious bacterial infection (SBI) in children with fever without source who have been vaccinated against Streptococcus pneumoniae, Canadian researchers report.

In a study published online in Archives of Disease in Childhood, the researchers compared the diagnostic accuracy of surrogate markers and clinical evaluation in children aged 1 to 36 months who presented with fever (rectal temperature >38°C) but without an identified source of infection. Complete blood count, blood culture, and urine analysis and culture were performed; CRP and PCT were measured. The probability of SBI was also evaluated clinically by pediatric emergency physicians in a tertiary hospital using a visual analog scale.

Of the 328 children enrolled in the study, 54 (16%) were diagnosed with an SBI; 48 had urinary tract infections; 4 had pneumonias; 1 had meningitis; and 1 had bacteremia.

Based on similar AUCs (area under the curves) of the ROC (receiver operating characteristic) curves, the diagnostic properties of CRP, PCT, WBC, and ANC for detecting an SBI in this population were similar, and all were statistically superior to clinical evaluation. The researchers note, however, that a surrogate marker must be interpreted depending on the value obtained in each patient-the higher the result, the higher the probability of having an SBI.

Manzano S, Bailey B, Gervaix A, Cousineau J, Delvin E, Girodias JB. Markers for bacterial infection in children with fever without source. Arch Dis Child. 2011;96(5):440-446.