Abstract
Physicians are regularly faced with severely ill patients at risk of developing infections. In literature, standard care wards are often neglected, although their patients frequently suffer from a systemic inflammatory response syndrome (SIRS) of unknown origin. Fast identification of patients with infections is vital, as they immediately require appropriate therapy. Further, tools with a high negative predictive value (NPV) to exclude infection or bacteremia are important to increase the cost effectiveness of microbiological examinations and to avoid inappropriate antibiotic treatment. In this prospective cohort study, 2,384 patients with suspected infections were screened for suffering from two or more SIRS criteria on standard care wards. The infection probability score (IPS) and sepsis biomarkers with discriminatory power were assessed regarding their capacity to identify infection or bacteremia. In this cohort finally consisting of 298 SIRS-patients, the infection prevalence was 72%. Bacteremia was found in 25% of cases. For the prediction of infection, the IPS yielded 0.51 ROC-AUC (30.1% sensitivity, 64.6% specificity). Among sepsis biomarkers, lipopolysaccharide binding protein (LBP) was the best parameter with 0.63 ROC-AUC (57.5% sensitivity, 67.1% specificity). For the prediction of bacteremia, the IPS performed slightly better with a ROC-AUC of 0.58 (21.3% sensitivity, 65% specificity). Procalcitonin was the best discriminator with 0.78 ROC-AUC, 86.3% sensitivity, 59.6% specificity and 92.9% NPV. Furthermore, bilirubin and LBP (ROC-AUC: 0.65, 0.62) might also be considered as useful parameters. In summary, the IPS and widely used infection parameters, including CRP or WBC, yielded a poor diagnostic performance for the detection of infection or bacteremia. Additional sepsis biomarkers do not aid in discriminating inflammation from infection. For the prediction of bacteremia procalcitonin, and bilirubin were the most promising parameters, which might be used as a rule for when to take blood cultures or using nucleic acid amplification tests for microbiological diagnostics.
Highlights
Systemic inflammatory response syndrome (SIRS) is defined as an acute host reaction to various different stimuli, including both infectious and non-infectious causes
Improper use of antibiotics in the hospital setting may favor the emergence of multi-resistant bacteria and may be associated with adverse drug reactions resulting in prolonged hospitalization and decreased cost efficiency [3,4,5]
Patients from 27 different standard care wards (14 medical and 13 surgical wards) with clinical suspicion of bacterial infection and for whom blood culture was requested were screened for the following inclusion criteria: two or more SIRS criteria, age greater than or equal to 18 years, and the ability to give consent
Summary
Systemic inflammatory response syndrome (SIRS) is defined as an acute host reaction to various different stimuli, including both infectious and non-infectious causes. The definition of SIRS is based on physiological parameters including body temperature, heart beat rate, respiration rate (or oxygen saturation), as well as abnormalities in leukocyte counts (leukocytosis, an elevation of immature neutrophils or leukopenia) [1]. These criteria are applicable and imply patients without major inflammatory disorders and are not specific. Physicians often rely on classical microbiological methods, e.g. blood cultures, to identify possible infection sources. These methods, may need several days before results are gained. The costs of unnecessary blood culture requests, especially when false positive are included, are substantial [9,10]
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