Download MendeleyStructural Basis of Reduced Susceptibility to Ceftazidime-Avibactam and Cefiderocol inEnterobacter cloacaeDue to AmpC R2 Loop Deletion.
Kawai, A., McElheny, C.L., Iovleva, A., Kline, E.G., Sluis-Cremer, N., Shields, R.K., Doi, Y.(2020) Antimicrob Agents Chemother 64
- PubMed: 32284381
- DOI: https://doi.org/10.1128/AAC.00198-20
- Primary Citation of Related Structures:
6LC7, 6LC8, 6LC9 - PubMed Abstract:
Ceftazidime-avibactam and cefiderocol are two of the latest generation β-lactam agents that possess expanded activity against highly drug-resistant bacteria, including carbapenem-resistant Enterobacterales Here, we show that structural changes in AmpC β-lactamases can confer reduced susceptibility to both agents. A multidrug-resistant Enterobacter cloacae clinical strain (Ent385) was found to be resistant to ceftazidime-avibactam and cefiderocol without prior exposure to either agent. The AmpC β-lactamase of Ent385 (AmpC Ent385 ) contained an alanine-proline deletion at positions 294 and 295 (A294_P295del) in the R2 loop. AmpC Ent385 conferred reduced susceptibility to ceftazidime-avibactam and cefiderocol when cloned into Escherichia coli TOP10. Purified AmpC Ent385 showed increased hydrolysis of ceftazidime and cefiderocol compared to AmpC Ent385Rev , in which the deletion was reverted. Comparisons of crystal structures of AmpC Ent385 and AmpC P99 , the canonical AmpC of E. cloacae complex, revealed that the two-residue deletion in AmpC Ent385 induced drastic structural changes of the H-9 and H-10 helices and the R2 loop, which accounted for the increased hydrolysis of ceftazidime and cefiderocol. The potential for a single mutation in ampC to confer reduced susceptibility to both ceftazidime-avibactam and cefiderocol requires close monitoring.
Organizational Affiliation:
Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.
