Tübingen, February 2, 2022
Bloodstream infections (BSI) are serious bacterial infections associated with high mortality. A research team developed the clinical BLOOMY* scores in order to identify risk factors and thus be able to predict short- and long-term mortality more precisely on the one hand, and to improve diagnostic and therapeutic options on the other. Research leader Prof. Evelina Tacconelli from Tübingen conducted the study of the German Center for Infection Research (DZIF) under the leadership of the University Hospitals of Tübingen and Freiburg. The University Hospitals of Berlin, Gießen, Cologne and Lübeck are also involved - the results were published in the renowned journal Lancet Infectious Diseases.
The number of bloodstream infections caused by multi-resistant pathogens (MRE) has skyrocketed in the last decade: according to European data, roughly 6 percent of hospitalized patients contract a BSI, or about 3.2 million cases each year. About 150,000 individuals die from the disease. In general, the intensity and course of a bacterial infection are determined by the germs that cause it, the patient's underlying health status, and the infection's treatment. The effects can continue for months after patients have been released from the hospital.
Although predictive models for prognosis already exist, they have so far been limited to specific pathogens or intensive care patients and mainly concern the short-term prognosis within the hospital stay. The long-term effects of bloodstream infection after discharge have only become the focus of researchers in recent years.
BLOOMY* multicentre cohort study on 14-day and six-month mortality
With the aim of being able to better predict short- and long-term mortality in patients with BSI both in normal and intensive care units and with different germs, data were prospectively collected for the multicentre cohort study led by Prof. Evelina Tacconelli with around 2,500 patients at all sites. Microbiological, clinical, laboratory-chemical as well as treatment and survival data played a role in the investigation of 14-day and six-month mortality; in total, more than 1,000 variables per patient were analyzed. Based on these, mathematical models for the early prediction of mortality after 14 days and after six months could be created.
The researchers found that factors such as age, previous malignant diseases and certain germs as well as BMI, platelet and leukocyte counts and the inflammation marker CRP were just as decisive for both time periods as the question of whether the affected person had been ill in hospital. On the one hand, additional variables for predicting 14-day mortality were mental status, low blood pressure and the need for mechanical ventilation. For the prediction of six-month mortality, on the other hand, the focus of infection, complications during hospitalization and kidney function at the end of treatment were additionally relevant.
The result of the study
The evaluation results were combined into two clinical scores that can be used to predict 14-day and six-month mortality much more precisely at an early stage of the disease. Both scores were then successfully validated for their predictive power in a further 1,000 patients from the various centers.
"Our study shows that the BLOOMY* scores have good discriminatory power and thus predictive power with regard to short- and long-term mortality after bloodstream infection and that we can use them to develop differentiated BSI management protocols," explains DZIF study leader Prof Evelina Tacconelli. Senior physician Dr Siri Göpel, a member of the research group from Tübingen, explains: "We can thus identify those patients at very high risk early on in the course of treatment and monitor them more closely, for example. Even after discharge, patients with a high long-term risk could be monitored specifically. Further studies could evaluate whether special measures can improve the prognosis in these patients."
*(BLOOMY = BLOOdstream infection due to multidrug-resistant organisms: Multicenter studY on risk factors and clinical outcomes)
Tacconelli E, Göpel S, Gladstone BP, Eisenbeis S, Hölzl F, Buhl M, Górska A, Cattaneo C, Mischnik A, Rieg S, Rohde AM, Kohlmorgen B, Falgenhauer J, Trauth J, Käding N, Kramme E, Biehl LM, Walker SV, Peter S, Gastmeier P, Chakraborty T, Vehreschild MJ, Seifert H, Rupp J, Kern WV; DZIF BLOOMY study group. Development and validation of BLOOMY prediction scores for 14-day and 6-month mortality in hospitalised adults with bloodstream infections: a multicentre, prospective, cohort study. Lancet Infect Dis. 2022 Jan 19:S1473-3099(21)00587-9. doi: 10.1016/S1473-3099(21)00587-9.
Dr. Evelina Tacconelli is a former project leader of the Cluster of Excellence “Controlling Microbes to Fight Infections” (CMFI).
Nature - Behind the paper