Development of diagnostic prediction tools for bacteraemia caused by 3rd generation cephalosporin-resistant Enterobacteriaceae in suspected bacterial infections: a nested case-control study

Abstract

OBJECTIVES: Current guidelines for empiric antibiotic treatment poorly predict the presence of 3rd generation cephalosporin-resistant Enterobacteriaceae bacteraemia (3GCR-E-Bac) as a cause of infection, thereby increasing unnecessary carbapenem use. We aimed to develop diagnostic scoring systems to better predict the presence of 3GCR-E-Bac. METHODS: A retrospective nested case-control study was performed that included patients ≥18 years from eight Dutch hospitals in whom blood cultures were obtained and intravenous antibiotics were initiated. Each patient with 3GCR-E-Bac was matched to four control infection episodes within the same hospital, based on blood culture date and onset location (community or hospital). Starting from 32 commonly described clinical risk factors available at infection onset, selection strategies were used to derive scoring systems for the probability of community- and hospital-onset 3GCR-E-Bac. RESULTS: 3GCR-E-Bac occurred in 90 of 22,506 (0.4%) community-onset and in 82 of 8,110 (1.0%) hospital-onset infections, and these cases were matched to 360 community-onset and 328 hospital-onset control episodes. The derived community-onset and hospital-onset scoring systems consisted of 6 and 9 predictors, respectively. With selected score cutoffs, the models identified 3GCR-E-Bac with equal sensitivity as existing guidelines (community-onset: 54.3%; hospital-onset: 81.5%). Yet, they reduced the proportion of patients classified as at risk for 3GCR-E-Bac (i.e. eligible for empiric carbapenem therapy) with 40% (95% confidence interval 21-56%) and 49% (95% confidence interval 39-58%) in, respectively, community-onset and hospital-onset infection. CONCLUSIONS: These prediction scores for 3GCR-E-Bac, specifically geared towards the initiation of empiric antibiotic treatment, may improve the balance between inappropriate antibiotics and carbapenem overuse.