Serious Bacterial Infection

Serious Bacterial Infection

Introduction: Some trial have reported that acute phase reactants, including C-reactive protein (CRP) may be helpful in determining the cause of fever in children. The diagnostic properties of quantitative CRP were compared in this prospective cohort investigation with other clinical and laboratory predictors of occult serious bacterial infection (SBI) in young children with fever without an apparent source of infection.

Methods: The age range of 77 children with a clinically undetectable sources of fever evaluated in the emergency department (ED) between January 1,2000 and October 31,2000 was 1 to 36 months (mean, 9.7 months). All participants had temperatures of 39 C  or higher. Demographic information, ED temperature, duration of fever, and clinical evaluation by the Yale observation score were reviewed at the time of initial evaluation.

Also assessed were the white blood cell count, band count, absolute neutrophil count, and CRP concentration. Blood cultures and either a screening urinalysis or a urine culture were performed. Chest radiographs were performed at the discretion of the ED physician. Patients who used antibiotics within the week prior to their visit to the ED were excluded. The primary outcome measure was the presence of laboratory or radiographically proven SBI (bacteremia, meningitis, urinary tract infection, pneumonia, septic arthritis, and osteomyelitis).

Results: Of 14 patients who had SBI, 4 had pneumonia, including 1 patient with Streptococcus pneumoniae becteremia; 6 had urinary tract infections and 4 had occult S pneumoniae becteremia. Sixty-three patients did not have SBI. Three were no between group differences in age, gender, ED temperature, duration of fever, or Yale observation scale. Measures of CRP concentration, white blood cell count, and absolute neutrophil count were significantly different between the 2 groups.

A multivariate logistic regression analysis showed that only CRP remained as a predictor of SBI (Beta = 0.76; 95% CI, 0.64-0.89). Receiver-operator characteristic analysis showed CRP (area under curve [AUC], 0.905; standard error [SE], 0.05; 95% CI, 0.808-1.002) was superior to absolute neutrophil count (AUC, 0.805; SE, 0.051; 95% CI, 0.705-0.905) and white blood cell count (AUC, 0.761; SE, 0.068; 95% CI, 0.628-0.895).

A CRP cutoff point of 7 was considered to maximize both sensitivity and specificity (sensitivity, 79%; specificity, 91%; likelihood ratio, 8.3; 95% CI, 3.8- 27.3). Multilevel likelihood ratios and posttest probabilities were determined for a variety of CRP levels. A CRP concentration of below 5 mg/dL effectively eliminated SBI (likelihood ratio, 0.087; 95% CI, 0.02-0.38; posttest probability of SBI, 1.9%).

Conclusion: Quantitative CRP concentration is a valuable laboratory test in the examination of febrile young children at risk for occult bacteremia and SBI. It has a better predictive value than white blood cell count or absolute neutrophil count.