In patients with community-acquired pneumonia (CAP), using fever as an indicator of blood culture (BC) necessity for detecting bacteremia warrants reevaluation, according to study results published in CHEST.
Although BCs are the gold standard for detecting bacteremia, their use in patients with CAP is questionable because bacteremia may evolve without perceivable signs of fever or hypothermia. Researchers sought to determine the prevalence of patients with CAP and afebrile bacteremia and identify clinical characteristics predicting the necessity for BCs in patients who are afebrile.
Bacteremia rates were determined in 4349 patients with CAP who were enrolled in a multinational cohort study and stratified by presence of fever at first patient contact. The researchers found that more than one-third of patients with bacteremic CAP (34.6%) were afebrile. No significant differences in demographics, comorbidities, severity of disease, and inflammatory parameters were found between patients with CAP with febrile and afebrile bacteremia. However, the 28-day mortality rate was more than doubled in afebrile bacteremia compared with febrile bacteremia. The distribution of main bacterial pathogens also did not differ between patients with afebrile bacteremia and patients with febrile bacteremia.
Independent positive predictors of bacteremia in patients with afebrile CAP included a positive pneumococcal urinary antigen test, C-reactive protein (CRP) level >200 mg/L, and blood urea nitrogen (BUN) level of ≥30 mg/dL. Antibiotic pretreatment significantly reduced, but did not eliminate, the likelihood of bacteremia in afebrile CAP.
The researchers concluded that, “the presence of fever or CURB-65 score ≥2 should not be the only triggers for BC sampling in hospitalized patients.” They added that, “Patients who are afebrile with positive pneumococcal urinary antigen regardless of antibiotic pretreatment and patients who are afebrile with high CRP level and elevated BUN level in the absence of antibiotic pretreatment exhibited bacteremia rates >10% and should therefore undergo BC testing.”
Forstner C, Patchev V, Rohde G, et al; for the CAPNETZ Study Group. Rate and predictors of bacteremia in afebrile community-acquired pneumonia. CHEST 2020;157(3):529-539.