Clinical Features and Outcomes of Community-Acquired Pneumonia Caused by Influenza.

BACKGROUND

Long regarded as the second most common cause of community-acquired pneumonia (CAP), has recently been identified with almost equal frequency as pneumococcus in patients hospitalized for CAP. The literature lacks a detailed description of the presentation, clinical features, laboratory and radiologic findings, and outcomes in pneumonia.

METHODS

During 2 prospective studies of patients hospitalized for CAP, we identified 33 patients with pneumonia. In order to provide context, we compared clinical findings in these patients with findings in 36 patients with pneumococcal pneumonia identified during the same period. We included and analyzed separately data from patients with viral coinfection. Patients with coinfection by other bacteria were excluded.

RESULTS

pneumonia occurred in older adults who had underlying chronic lung disease, cardiac conditions, and alcohol use disorder, the same population at risk for pneumococcal pneumonia. However, in contrast to pneumococcal pneumonia, patients with pneumonia had less severe infection as shown by absence of septic shock on admission, less confusion, fewer cases of leukopenia or extreme leukocytosis, and no deaths at 30 days. Viral coinfection greatly increased the severity of , but not pneumococcal pneumonia.

CONCLUSIONS

We present the first thorough description of pneumonia, show that it is less severe than pneumococcal pneumonia, and document that viral coinfection greatly increases its severity. These distinctions are lost when the label CAP is liberally applied to all patients who come to the hospital from the community for pneumonia.