Bloodstream infections caused by Escherichia coli producing AmpC β-lactamases: epidemiology and clinical features

V. Pascual, N. Alonso, M. Simó, G. Ortiz, M. C. Garcia, M. Xercavins, A. Rivera, M. A. Morera, E. Miró, E. Espejo, F. Navarro, M. Gurguí, J. Pérez, M. Rodríguez-Carballeira, J. Garau, E. Calbo

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© 2016, Springer-Verlag Berlin Heidelberg. The aim of the study was to investigate the epidemiology and clinical features of bloodstream infections due to Escherichia coli producing AmpC β-lactamases (AmpC-Ec-BSI). In a multi-centre case–control study, all third-generation-cephalosporin-resistant Escherichia coli BSI (3GC-Ec-BSI) isolates were analysed. Acquired blaAmpC (blaac-AmpC) detection was done by polymerase chain reaction (PCR) and sequencing. Chromosomal blaAmpC (blac-AmpC) expression was quantified by real-time PCR. Cases were patients with AmpC-Ec-BSI. Controls were patients with cephalosporin-susceptible E. coli BSI, matched 1:1 by sex and age. Demographics, comorbidities, intrinsic and extrinsic risk factors for antimicrobial resistance, clinical presentation and outcomes were investigated. Among 841 E. coli BSI, 17 were caused by AmpC-Ec (2 %). Eleven isolates (58.8 %) had blaac-AmpC and six were blac-AmpC overproducers. The mean age of cases was 66.2 years and 71 % were men. Cases were more frequently healthcare-related (82 vs. 52 % controls, p < 0.05) and presented more intrinsic and extrinsic risk factors. At least one risk factor was present in 94.1 % of cases vs. 41.7 % of controls (p = 0.002). Severity and length of stay (LOS) were higher among cases (mean Pitt Score 2.6 vs. 0.38 in controls, p = 0.03; LOS 17.5 days vs. 6 in controls, p = 0.02). Inappropriate empirical therapy (IET) was administered to 70.6 % of cases and 23.5 % of controls (p < 0.003). No differences were found in terms of cure rate at the 14th day and mortality. Bloodstream infections due to AmpC-Ec (mostly plasmid-mediated) are infrequent in our area. AmpC-Ec-BSI affects mainly patients with intrinsic risk factors and those with previous antibiotic exposure. A high proportion received IET.
Original languageEnglish
Pages (from-to)1997-2003
JournalEuropean Journal of Clinical Microbiology and Infectious Diseases
Issue number12
Publication statusPublished - 1 Dec 2016


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