The clinical host response to microbial infection in medical patients with fever

Study objectives: Predictors among demographic, clinical, and laboratory variables for a microbial (nonviral/nonchlamydial) infection in hospitalized medical patients with new onset of fever (temperature greater than or equal to 38.0 degrees C axillary or greater than or equal to 38.3 degrees C rectal) were analyzed and compared with the criteria for the systemic inflammatory response syndrome (SIRS), including an abnormal body temperature and WBC count, tachypnea and tachycardia, and sepsis, defined as SIRS and the presence of a clinical infection. Design: A prospective cohort study. Setting: Department of internal medicine at a university hospital. Patients: In 300 hospitalized medical patients with new onset of fever, demographic, clinical, and laboratory variables were obtained during the first 2 days after inclusion, and peak and nadir values, when appropriate, were taken. Microbiologic results for 7 days were collected. Clinical information was used to decide on the presence of a clinical infection. Measurements and results: One hundred thirty-three of 300 patients (44%) had a microbial infection: 26% suffered from local microbial infection only 9% from bacteremia only, and 9% had bloodstream plus local microbial infections. Patients with a microbial infection had a higher World Health Organization performance score at home (p < 0.05), higher peak body temperature (p < 0.001), higher nadir and peak WBC counts (p < 0.05), lower nadir platelet count (p < 0.01), higher peak alanine and aspartate aminotransferases (p < 0.01), and lower nadir albumin (p < 0.001) levels in blood during the first 2 days after inclusion than those without infection. Using multivariate techniques, predictors for microbial infection or bacteremia alone, independent of age, sex, underlying disease, and clinical infection, were peak temperature, peak WBC count, and nadir platelet count and albumin level. In contrast, conventional SIRS/sepsis definitions and criteria predicted microbial infection less well, mainly because tachypnea and tachycardia were of no predictive value. Conclusions: In febrile medical patients, microbial infection can be predicted with use of easily obtained clinical and laboratory variables, including peak temperature, peak WBC count, and nadir platelet count and albumin level within the first 2 days. The new model predicted microbial infection better than conventional SIRS/sepsis criteria. This may help to improve the clinical recognition of the systemic host response to microbial infection and to refine SIRS/sepsis definitions.