Available online 8 July 2022, 151557

To report the detection of the class D carbapenemase OXA-181 in an MDR clinical Pseudomonas aeruginosa isolate in Germany.

Carbapenemase detection was performed by using several phenotypic tests such as the modified Hodge test, a combined disc test with boronic acid, EDTA or cloxacillin, a lysate-based inhibition assays and by PCR for common and rare carbapenemase genes. Antibiotic susceptibilities were determined by broth microdilution. The genetic environment of blaOXA-181 in the clinical P. aeruginosa isolate was characterized by Illumina and MinION sequencing.

An multidrug-resistant P. aeruginosa was isolated from a tracheal swab in 2019 and was sent to the German National Reference Centre for multidrug-resistant Gram-negative bacteria for carbapenemase detection. Several phenotypic tests indicated the presence of a carbapenemase which was not inhibited by EDTA nor by boronic acid. PCRs for common and rare carbapenemase genes revealed the presence of a blaOXA-181 gene. WGS data confirmed that the gene was located on the chromosome as part of a Tn2013 transposon. The genetic organization of blaOXA-181 has already been described in a P. aeruginosa isolate from England, but both isolates differed significantly in their sequence types (ST111/ST235). Analysis of the genetic environment of the blaOXA-181 gene also revealed high homology to a plasmid from a Klebsiella pneumoniae isolate.

To our knowledge, this is the first report of blaOXA-181 in a clinical P. aeruginosa isolate in Germany which emphasizes the ongoing spread of yet unusual carbapenemases among different Gram-negative species and therefore complicating their detection in routine laboratories.

© 2022 The Author(s). Published by Elsevier GmbH.