Identification of clinical risk factors for nosocomial pneumococcal bacteremia

Clinical risks for nosocomial pneumococcal bacteremia (NPB) have been analyzed previously in case series, a study design inadequate for this purpose. Therefore, we performed a case-control study of NPB, pairing each of 37 cases identified retrospectively at the Minneapolis Veterans Affairs Medical Center from the period of 1984-1994 with four or five hospitalized controls. Comorbidities identified at the time of admission that were significantly associated with NPB on univariate and multivariate analysis included respiratory or hematologic malignancy, anemia, chronic obstructive pulmonary disease, and coronary artery disease. All characteristic symptoms and signs of pneumococcal infection were significantly more common in cases than in controls. NPB was strongly associated with death within 7 days of the index blood culture date, and the mortality rate among cases was 40.5%, compared with 1.2% among nonbacteremic controls (P < .00001). We conclude that NPB is a highly lethal infection that is associated with distinct but identifiable clinical risks, symptoms, and signs.