Things We Do For No Reason: Routine Blood Culture Acquisition for Children Hospitalized with Community-Acquired Pneumonia

One difficulty in interpreting these data is that each publication used a different definition of “complicated” pneumonia, probably due to differences in data sources. Neuman et al. incorporated the narrowest definition of severe and complicated pneumonia as patients who were either admitted to an intensive care unit (ICU) or who underwent a pleural drainage procedure.⁹ Myers’ and Shah’s definitions were similar to each other but much broader than that of Neuman et al. Shah et al. included lung abscess/necrosis, parapneumonic effusion/empyema, or bronchopleural fistula.¹¹ Myers et al. included the same indications but qualified their pleural fluid effusions as “moderate-to-large” and any effusion that required pleural drainage procedure.⁸ Myers et al. also reported bacteremia in 75% of patients with metastatic complications, including osteomyelitis.⁸ These definitions of complicated pneumonia may at least partially explain the differences noted in the rates of bacteremia in complicated pneumonia, with the patients in the study of Myers et al. potentially representing the most severe cohort and with the highest rate of bacteremia^8,9 (Table).

These studies not only support the definition of complicated pneumonia put forward by the IDSA but also provide further information, though imperfect, on how to define “moderate to severe.” All the patients with bacteremia in the report of Heine et al. had complicated pneumonia and were described on chart review as either toxic-appearing or requiring ICU care.⁷ This, in addition to the inclusion of ICU care in the definition of complicated pneumonia of Neuman et al.,⁹ indicates that children with CAP requiring ICU care may be at higher risk of bacteremia. In fact, the British Thoracic Society guidelines do not recommend microbiological investigations of children with CAP, including blood culture, unless a child requires ICU care.²⁰

Given the low rate of bacteremia in CAP, the risk of blood culture contaminants, and the small likelihood that isolation of a pathogen alters treatment for children, we recommend not using hospital admission as the determining factor for blood culture acquisition. Instead, we recommend a more targeted approach. To achieve a higher rate of true-positive bacteremia in immunocompetent children with up-to-date vaccinations, we recommend acquiring a blood culture in children with complicated pneumonia, metastatic complications, or with ICU needs. By initiating the IDSA-recommended ampicillin/amoxicillin in the remaining hospitalized patients and acquiring blood cultures for the minority of patients who do not improve, we can increase the likelihood of isolating penicillin-resistant bacteria.

Attempting to balance the importance of identifying clinically important bacteremia for children hospitalized with CAP and the inherent risks of obtaining blood cultures for all hospitalized patients, Andrews et al. created and analyzed a cost-effectiveness model. The authors compared universal acquisition of blood cultures for hospitalized children with CAP versus a targeted approach with blood cultures obtained in patients with effusion or empyema, requiring ICU care, or who are immunosuppressed. Based on this model, a targeted approach could save more than $187 million annually, reduce the number of cultures needed to result in a meaningful change in antibiotic therapy for one patient from 122 to 42, and would “miss” only approximately one case of bacteremia resulting in treatment failure per 1,400 patients.¹⁷