OBJECTIVES: To characterize the mechanisms involved in the reduced carbapenem susceptibility of five Acinetobacter pittii strains isolated from different regions of Germany. METHODS: The strains were analysed by susceptibility testing, phenotypic tests for metallo-β-lactamase production, sequencing of the integron structure and strain typing by PFGE, as well as multilocus sequence typing (MLST) and plasmid analysis by S1 restriction and hybridization. RESULTS: Despite GIM-1 production, the MICs of imipenem were only 4 mg/L for four strains and some methods of phenotypic MBL detection failed. According to PFGE and MLST, the strains belonged to four different clones, but blaGIM-1 was present in identical integron structures in all strains and carried on plasmids of ∼60 kb. CONCLUSIONS: For the first time, GIM-1 has been demonstrated in A. pittii. This resistance mechanism has previously been reported only in Enterobacteriaceae and Pseudomonas aeruginosa. As GIM-1 was found in strains with diverse clonal backgrounds, but encoded on plasmids of a similar size, further spread among Acinetobacter spp. seems possible. The detection of GIM-1 production might be challenging in some strains due to the low MICs of carbapenems.
OBJECTIVES: To characterize the mechanisms involved in the reduced carbapenem susceptibility of five Acinetobacter pittii strains isolated from different regions of Germany. METHODS: The strains were analysed by susceptibility testing, phenotypic tests for metallo-β-lactamase production, sequencing of the integron structure and strain typing by PFGE, as well as multilocus sequence typing (MLST) and plasmid analysis by S1 restriction and hybridization. RESULTS: Despite GIM-1 production, the MICs of imipenem were only 4 mg/L for four strains and some methods of phenotypic MBL detection failed. According to PFGE and MLST, the strains belonged to four different clones, but blaGIM-1 was present in identical integron structures in all strains and carried on plasmids of ∼60 kb. CONCLUSIONS: For the first time, GIM-1 has been demonstrated in A. pittii. This resistance mechanism has previously been reported only in Enterobacteriaceae and Pseudomonas aeruginosa. As GIM-1 was found in strains with diverse clonal backgrounds, but encoded on plasmids of a similar size, further spread among Acinetobacter spp. seems possible. The detection of GIM-1 production might be challenging in some strains due to the low MICs of carbapenems.
Authors: Andreas F Wendel; Sofija Ressina; Susanne Kolbe-Busch; Klaus Pfeffer; Colin R MacKenzie Journal: Appl Environ Microbiol Date: 2016-05-31 Impact factor: 4.792
Authors: Andreas F Wendel; Martin Kaase; Ingo B Autenrieth; Silke Peter; Philipp Oberhettinger; Heime Rieber; Klaus Pfeffer; Colin R MacKenzie; Matthias Willmann Journal: Antimicrob Agents Chemother Date: 2017-02-23 Impact factor: 5.191