Carbapenemases in Germany in 2025 and the impact of changing the isolate submission criteria of the German National Reference Centre for multidrug-resistant Gram-negative bacteria

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• Picked for Microbiology (medical) (top studies of the week, 8 November 2026): National carbapenemase detection methods and resistance surveillance

Abstract

BACKGROUND: The German National Reference Centre for multidrug-resistant Gram-negative bacteria at the Department of Medical Microbiology of the Ruhr University Bochum offers the free service of carbapenemase detection or confirmation to German laboratories in order to obtain molecular surveillance data on the spread of carbapenemases in Germany. To prevent capacity overload, the NRC had to sharpen the submission criteria in march 2025 to achieve a better pre-selection of isolates submitted and eventually reduce the number of isolates analyzed. METHODS: Species identification was performed using MALDI-TOF MS. Carbapenemase detection was performed using a set of phenotypic assays and PCRs targeting the common carbapenemase genes in Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii, followed by sequencing of PCR products for allele identification and Illumina whole genome sequencing when indicated. RESULTS: Compared to 2024, the number of isolates submitted for carbapenemase detection decreased by 18.6% to 8307. Carbapenemase detections on the other hand increased by 13% to 6.058. The major carbapenemases in Enterobacterales were OXA-48, OXA-244, NDM-5, NDM-1, KPC-2 and VIM-1, while in P. aeruginosa, VIM-2 predominated and OXA-23 and OXA-72 were the most prevalent carbapenemases identified in A. baumannii. The proportion of carbapenemase-positive isolates increased significantly, especially for isolates of P. aeruginosa and Enterobacter cloacae complex. CONCLUSIONS: The sharpened submission criteria led to a drop in isolates sent for analysis in 2025. Nonetheless, the number of carbapenemase-positive isolates increased significantly compared to 2024, indicating that the changed criteria had no negative impact on sensitivity, but a positive effect on specificity for carbapenemase production. This alarming observation indicates that carbapenemases are increasingly spreading in Germany.

Abstract as published, via PubMed.