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Purpose: To analyze the longitudinal epidemiology and antimicrobial resistance (AMR) patterns of Gram-negative bloodstream infections (BSI) in Germany., Methods: Post-hoc analysis of prospectively documented BSI due to Escherichia coli, Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa and Acinetobacter baumannii from six university hospitals between 2016 and 2020. In a subanalysis 1228 episodes of BSI (E. coli N = 914, Klebsiella spp. N = 314) were analyzed for clinical endpoints and risk factors., Results: E. coli was the most prevalent cause of BSI, with 5412 cases, followed by Klebsiella spp. (2148 cases), P. aeruginosa (789 cases), Enterobacter spp. (696 cases), and A. baumannii (31 cases). BSI incidence rates were particularly high in haematology/oncology, with E. coli BSI reaching 13.9 per 1000 admissions. Most (58%) of the BSI episodes were community-acquired. A notable finding was the moderate increase of third-generation cephalosporin resistant Enterobacterales (3GCREB) for E. coli from 13.9% in 2016 to 14.4% in 2020 and a decrease for Klebsiella spp. from 16.5% in 2016 to 11.1% in 2020 corresponding to extended-spectrum betalactamase (ESBL) phenotype. In our analysis, the 3GCREB phenotype was not associated with a higher risk of death or discharge with sequelae for E. coli and Klebsiella spp., Conclusion: Our study provides longitudinal data on Gram-negative BSI in Germany on a clinical basis for the first time. These data underscores the critical need for ongoing surveillance and more pathogen-related clinical data., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Species within the Enterobacter cloacae complex (ECC) include globally important nosocomial pathogens. A three-year study of ECC in Germany identified Enterobacter xiangfangensis as the most common species (65.5%) detected, a result replicated by examining a global pool of 3246 isolates. Antibiotic resistance profiling revealed widespread resistance and heteroresistance to the antibiotic colistin and detected the mobile colistin resistance (mcr)-9 gene in 19.2% of all isolates. We show that resistance and heteroresistance properties depend on the chromosomal arnBCADTEF gene cassette whose products catalyze transfer of L-Ara4N to lipid A. Using comparative genomics, mutational analysis, and quantitative lipid A profiling we demonstrate that intrinsic lipid A modification levels are genospecies-dependent and governed by allelic variations in phoPQ and mgrB, that encode a two-component sensor-activator system and specific inhibitor peptide. By generating phoPQ chimeras and combining them with mgrB alleles, we show that interactions at the pH-sensing interface of the sensory histidine kinase phoQ dictate arnBCADTEF expression levels. To minimize therapeutic failures, we developed an assay that accurately detects colistin resistance levels for any ECC isolate., (© 2023. The Author(s).)

Background: Prosthetic joint infections (PJI) are associated with high morbidity and costs. Various efforts have been made to improve the diagnosis of PJI over the past years, but only few studies have assessed the diagnostic utility of nucleic acid amplification test (NAAT) techniques in this context. Here, we report our experience with a commercial 16S rRNA gene PCR and an automated multiplex-PCR cartridge system in identifying pathogens causing PJI., Materials and Methods: A prospective single-centre study was performed including 54 patients with either septic or aseptic prosthetic joint replacement or surgical revision between February 2012 and April 2013. Conventional cultures of periprosthetic tissue samples were compared with the results of broad-range 16S rRNA gene real-time PCR (UMD-Universal Pathogen DNA Extraction and PCR Analysis, Molzym GmbH, Germany) and the multiplex-PCR Unyvero ITI(®) cartridge system (U-ITI; Curetis AG, Germany). Conventional culture and broad-range 16S rRNA gene real-time PCR were performed on all samples. U-ITI was used in a subgroup of 28 cases including all culture-positive cases. The agreement of the results from the methods was assessed., Results: Of 54 cases, seven were culture-positive. Broad-range 16S rRNA gene real-time PCR gave 6, U-ITI 3 concordant positive results. Of the 47 culture-negative samples, 46 were also negative by broad-range 16S rRNA gene real-time PCR resulting in a 96 % (52/54) agreement between 16S rRNA gene PCR and culture. Of the 21 culture-negative samples analysed with U-ITI, 20 gave negative results, including the single 16S rRNA gene PCR-positive/culture-negative specimen. The rate of agreement between U-ITI and culture results was 82 % (23/28)., Conclusion: This pilot study gave no indication of superiority of the used NAATs over conventional culture methods for the microbiological diagnosis of PJI. Drawbacks are susceptibility to contamination in the case of 16S rRNA gene real-time PCR, labour-intensive DNA extraction and limited pathogen panel in the case of the multiplex cartridge PCR system. More prospective trials are needed to evaluate the diagnostic performance of NAATs and their impact on the clinical management of PJI.