Ma Ke, Zong Zhiyong
Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, China.
Front Microbiol. 2022 Nov 4;13:1047109. doi: 10.3389/fmicb.2022.1047109. eCollection 2022.
Aztreonam-avibactam is a promising combination to treat carbapenem-resistant Enterobacterales including coverage for metallo-β-lactamases. strains resistant to aztreonam-avibactam have emerged but resistance mechanisms remain to be elucidated. We performed a study to investigate the mechanism for aztreonam-avibactam in a carbapenem-resistant clinical strain. This strain was resistant to aztreonam-avibactam (aztreonam MIC, 16 mg/L in the presence of 4 mg/L avibactam). Whole genome sequencing revealed that the strain carried metallo-β-lactamase gene and the extended-spectrum β-lactamase (ESBL) gene and had a YRIK four amino acid insertion in penicillin-binding protein 3 (PBP3). was cloned into pET-28a(+), followed by the transformation, with the gene, of strain 035125∆pCMY42 possessing the YRIK insertion in PBP3 and strain BL21 with the wildtype PBP3. , another common ESBL gene, and , a hybrid of and were also individually cloned into both strains for comparison. Aztreonam-avibactam resistance was only observed in the strains with the YRIK insertion in PBP3 that produced CTX-M-15 or its hybrid enzyme CTX-M-199. Checkerboard titration assays were performed to determine the synergistic effects between aztreonam-avibactam and ceftazidime or meropenem. Doubling avibactam concentration reversed aztreonam-avibactam resistance, while the combination of aztreonam-avibactam and ceftazidime or meropenem did not. In conclusion, CTX-M enzymes with activity against aztreonam, (e.g., CTX-M-15 and CTX-M-199), can confer resistance in the combination of PBP3 with YRIK insertions in metallo-β-lactamase-producing carbapenem-resistant . Doubling the concentration of avibactam may overcome such resistance.
氨曲南-阿维巴坦是一种很有前景的联合用药，可用于治疗耐碳青霉烯类肠杆菌科细菌，包括对金属β-内酰胺酶也有覆盖作用。对氨曲南-阿维巴坦耐药的菌株已经出现，但耐药机制仍有待阐明。我们开展了一项研究，以探究一株耐碳青霉烯类临床菌株对氨曲南-阿维巴坦耐药的机制。该菌株对氨曲南-阿维巴坦耐药（在存在4mg/L阿维巴坦的情况下，氨曲南的最低抑菌浓度为16mg/L）。全基因组测序显示，该菌株携带金属β-内酰胺酶基因和超广谱β-内酰胺酶（ESBL）基因，并且在青霉素结合蛋白3（PBP3）中有YRIK四个氨基酸的插入。将该基因克隆到pET-28a(+)中，随后将其转化到在PBP3中有YRIK插入的035125∆pCMY42菌株和具有野生型PBP3的BL21菌株中。另一个常见的ESBL基因以及一种由和杂交而成的基因也分别克隆到这两种菌株中进行比较。仅在PBP3中有YRIK插入且产生CTX-M-15或其杂交酶CTX-M-199的菌株中观察到对氨曲南-阿维巴坦的耐药性。进行棋盘滴定试验以确定氨曲南-阿维巴坦与头孢他啶或美罗培南之间的协同作用。将阿维巴坦浓度加倍可逆转对氨曲南-阿维巴坦的耐药性，而氨曲南-阿维巴坦与头孢他啶或美罗培南的联合用药则不能。总之，具有抗氨曲南活性的CTX-M酶（例如CTX-M-15和CTX-M-199）可在产金属β-内酰胺酶的耐碳青霉烯类细菌中PBP3有YRIK插入的情况下赋予耐药性。将阿维巴坦浓度加倍可能克服这种耐药性。
