Reduction of unnecessary antibiotic therapy in newborn infants using interleukin-8 and C-reactive protein as markers of bacterial infections.
OBJECTIVE
To examine whether the determination of interleukin 8 (IL-8) and C-reactive protein (CRP) in neonates with suspected nosocomial bacterial infection (NBI) is feasible and cost-effective in reducing antibiotic therapy.


METHODS
Between April 1996 and May 1997, IL-8 was measured 260 times along with blood cultures, CRP, and immature-to-total-neutrophil (IT) ratio for suspected NBI in term and preterm neonates. All infants were retrospectively analyzed for NBI. Sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated for IL-8, CRP, and IT ratio. Receiver-operating characteristic curves were analyzed to determine optimal thresholds. Between June 1997 and June 1998, IL-8 was measured 215 times in newborn infants with suspected NBI and the decision to start antibiotic therapy was based on increased IL-8 and/or CRP values. A cost-effectiveness analysis was performed and sensitivity, specificity, and receiver-operating characteristic curves were reevaluated.


RESULTS
At the first suspicion of NBI, the combination of IL-8 >/= 53 pg/mL and/or CRP >10 mg/L detected culture-proven NBI with 96% sensitivity. The combined culture-proven and clinical NBI were detected with 93% sensitivity and 80% specificity. The use of IL-8 reduced unnecessary antibiotic therapy for suspected NBI by 73% and was cost-effective when compared with initiating antibiotic therapy based on clinical signs alone or based on clinical signs and an increased IT ratio and/or CRP.


CONCLUSIONS
The combination of IL-8 and/or CRP is a reliable and early test for the diagnosis of NBI in newborn infants. Using the combination of IL-8 and/or CRP to restrict antibiotic therapy to truly infected infants reduces unnecessary antibiotic therapy and is cost-effective.
Franz
A R
AR
Department of Pediatrics, Division of Neonatology and Pediatric Critical Care, University of Ulm, Germany. axel.franz@medizin.uni-ulm.de
Steinbach
G
G
Kron
M
M
Pohlandt
F
F
D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000175:diagnosis* / Q000188:drug therapy*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis*; D003362:Cost-Benefit Analysis; D003428:Cross Infection / Q000175:diagnosis* / Q000188:drug therapy*; D004363:Drug Utilization / Q000706:statistics & numerical data; D006801:Humans; D007231:Infant, Newborn; D016209:Interleukin-8 / Q000097:blood*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D000900:Anti-Bacterial Agents; D015415:Biomarkers; D016209:Interleukin-8; D002097:C-Reactive Protein