Editors' ChoiceMicrobiology

“C”ing Bacterial Infections

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Science Translational Medicine  02 Jul 2014:
Vol. 6, Issue 243, pp. 243ec114
DOI: 10.1126/scitranslmed.3009628

Differentiating between bacterial and viral infections in febrile children is often challenging for clinicians. C-reactive protein (CRP) is an acute phase protein that is synthesized in response to inflammatory or infectious processes. The diagnostic capability of a single CRP blood measurement to predict bacterial infections in children varies widely, with sensitivities of 60 to 100% and specificities of 40 to 100%.

In a prospective observational study, Segal et al. now show that CRP values interpreted in the context of time from fever onset demonstrated better diagnostic characteristics than those of CRP values alone. In 373 febrile children (age range 0 to 16 years), 103 (28%) had a bacterial infection. The optimum cut-off for CRP to diagnose bacterial infection improved when time from fever onset was included. At ≤24 hours after fever onset, a CRP blood measurement of 7.5 mg/dL provided a post-test probability of infection of 75%. At >24 hours after fever onset, a CRP blood measurement of 11mg/dL provided a post-test probability of 75%. But a low CRP at ≤24 hours after fever onset did not rule out bacterial infection (post-test probability >10% with a CRP measurement of 1 mg/dL). However, a CRP measurement of ≤5 mg/dL at >24 hours after fever onset predicted the absence of bacterial infection with 94 to 95% accuracy.

Adjusting for the time of fever onset in febrile children and setting different cut-off values improved the diagnostic accuracy and clinical utility of CRP testing for bacterial infection.

I. Segal et al., Use of time from fever onset improves the diagnostic accuracy of C-reactive protein in identifying bacterial infections. Arch. Dis. Child. 10.1136/archdischild-2013-305640 (2014). [Full Text]

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