OBJECTIVES: Rahnella aquatilis is an environmental enterobacterial species with a chromosomal bla(RAHN-1) gene encoding extended-spectrum class A beta-lactamase RAHN-1. We describe the diversity of bla(RAHN) genes from two groups of strains, G1 and G2, isolated from raw fruits and vegetables, and the new class A beta-lactamase RAHN-2. METHODS: MICs were determined by Etest. bla(RAHN) genes were amplified by PCR, sequenced, and cloned to produce RAHN-1 and RAHN-2 proteins whose kinetic parameters were determined. RESULTS: All strains had similar beta-lactam resistance patterns. However, isolates of G1 were at least 2-fold more susceptible to piperacillin, amoxicillin, piperacillin/clavulanic acid, piperacillin/tazobactam and cefotaxime. Sequences of bla(RAHN) from G1 had <82.9% identity with that of bla(RAHN-1), whereas those of G2 were >92% identical. The RAHN-2 beta-lactamase was 89.8% identical to RAHN-1, 5-fold more efficient than RAHN-1 in hydrolysing ticarcillin and 2.5-fold more efficient in cefotaxime and cefuroxime hydrolysis. However, the specific activity of RAHN-1 was 2-fold higher than that of RAHN-2 suggesting that the bla(RAHN) genes are regulated differently. CONCLUSIONS: The new class A beta-lactamase RAHN-2 is phenotypically difficult to detect and requires MIC determination.
OBJECTIVES:Rahnella aquatilis is an environmental enterobacterial species with a chromosomal bla(RAHN-1) gene encoding extended-spectrum class A beta-lactamase RAHN-1. We describe the diversity of bla(RAHN) genes from two groups of strains, G1 and G2, isolated from raw fruits and vegetables, and the new class A beta-lactamase RAHN-2. METHODS: MICs were determined by Etest. bla(RAHN) genes were amplified by PCR, sequenced, and cloned to produce RAHN-1 and RAHN-2 proteins whose kinetic parameters were determined. RESULTS: All strains had similar beta-lactam resistance patterns. However, isolates of G1 were at least 2-fold more susceptible to piperacillin, amoxicillin, piperacillin/clavulanic acid, piperacillin/tazobactam and cefotaxime. Sequences of bla(RAHN) from G1 had <82.9% identity with that of bla(RAHN-1), whereas those of G2 were >92% identical. The RAHN-2 beta-lactamase was 89.8% identical to RAHN-1, 5-fold more efficient than RAHN-1 in hydrolysing ticarcillin and 2.5-fold more efficient in cefotaxime and cefuroxime hydrolysis. However, the specific activity of RAHN-1 was 2-fold higher than that of RAHN-2 suggesting that the bla(RAHN) genes are regulated differently. CONCLUSIONS: The new class A beta-lactamase RAHN-2 is phenotypically difficult to detect and requires MIC determination.
Authors: Adam C Martiny; Jennifer B H Martiny; Claudia Weihe; Andrew Field; Julie C Ellis Journal: Front Microbiol Date: 2011-11-29 Impact factor: 5.640
Authors: Diana C Mogrovejo; Laura Perini; Cene Gostinčar; Kristina Sepčić; Martina Turk; Jerneja Ambrožič-Avguštin; Florian H H Brill; Nina Gunde-Cimerman Journal: Front Microbiol Date: 2020-04-03 Impact factor: 5.640