Do Afebrile CAP Patients Need Blood Cultures?

December 12, 2019

Written by Clay Smith

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Presence or absence of fever at the time of presentation should not determine whether or not blood cultures are obtained in patients with community acquired pneumonia (CAP).

Why does the matter?
Recent CAP guidelines suggest we should omit blood cultures in outpatients and inpatients with mild disease. Fever is a classic trigger to obtain blood cultures. But how often do patients with CAP have bacteremia and no fever?

A hot topic
This was a large retrospective database study in Germany with 4,349 patients, the CAPNETZ Network. Bacteremia was present in, “190 of 2,116 patients who were febrile (8.9%), 101 of 2,149 patients who were not afebrile (4.7%).” S. pneumoniae was by far the most common pathogen in both febrile and afebrile patients. Patients who were afebrile with bacteremia had higher mortality at 28 days: 9.9% afebrile vs 3.7% febrile CAP patients. They found that positive urinary pneumococcal antigen test, high CRP >200, and BUN >30 were all independent predictors of afebrile bacteremia. Pretreatment with antibiotics was a negative predictor. This suggests that absence of fever should not deter us from obtaining a blood culture if there are other reasons to obtain one based on the recent CAP guidelines.

Source
Rate and Predictors of Bacteremia in Afebrile Community-Acquired Pneumonia. Chest. 2019 Oct 26. pii: S0012-3692(19)34102-9. doi: 10.1016/j.chest.2019.10.006. [Epub ahead of print]

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