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López-Argüello S, Montaner M, Sayed ARM, Oliver A, Bulitta JB, Moya B. Penicillin-Binding Protein 5/6 Acting as a Decoy Target in Pseudomonas aeruginosa Identified by Whole-Cell Receptor Binding and Quantitative Systems Pharmacology. Antimicrob Agents Chemother 2023; 67:e0160322. [PMID: 37199612 PMCID: PMC10269149 DOI: 10.1128/aac.01603-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 04/23/2023] [Indexed: 05/19/2023] Open
Abstract
The β-lactam antibiotics have been successfully used for decades to combat susceptible Pseudomonas aeruginosa, which has a notoriously difficult to penetrate outer membrane (OM). However, there is a dearth of data on target site penetration and covalent binding of penicillin-binding proteins (PBP) for β-lactams and β-lactamase inhibitors in intact bacteria. We aimed to determine the time course of PBP binding in intact and lysed cells and estimate the target site penetration and PBP access for 15 compounds in P. aeruginosa PAO1. All β-lactams (at 2 × MIC) considerably bound PBPs 1 to 4 in lysed bacteria. However, PBP binding in intact bacteria was substantially attenuated for slow but not for rapid penetrating β-lactams. Imipenem yielded 1.5 ± 0.11 log10 killing at 1h compared to <0.5 log10 killing for all other drugs. Relative to imipenem, the rate of net influx and PBP access was ~ 2-fold slower for doripenem and meropenem, 7.6-fold for avibactam, 14-fold for ceftazidime, 45-fold for cefepime, 50-fold for sulbactam, 72-fold for ertapenem, ~ 249-fold for piperacillin and aztreonam, 358-fold for tazobactam, ~547-fold for carbenicillin and ticarcillin, and 1,019-fold for cefoxitin. At 2 × MIC, the extent of PBP5/6 binding was highly correlated (r2 = 0.96) with the rate of net influx and PBP access, suggesting that PBP5/6 acted as a decoy target that should be avoided by slowly penetrating, future β-lactams. This first comprehensive assessment of the time course of PBP binding in intact and lysed P. aeruginosa explained why only imipenem killed rapidly. The developed novel covalent binding assay in intact bacteria accounts for all expressed resistance mechanisms.
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Affiliation(s)
- Silvia López-Argüello
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Maria Montaner
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Alaa RM. Sayed
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Department of Chemistry, Faculty of Science, Fayoum University, Fayoum, Egypt
| | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Jürgen B. Bulitta
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Bartolome Moya
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
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Barceló IM, Jordana-Lluch E, Escobar-Salom M, Torrens G, Fraile-Ribot PA, Cabot G, Mulet X, Zamorano L, Juan C, Oliver A. Role of Enzymatic Activity in the Biological Cost Associated with the Production of AmpC β-Lactamases in Pseudomonas aeruginosa. Microbiol Spectr 2022; 10:e0270022. [PMID: 36214681 PMCID: PMC9604156 DOI: 10.1128/spectrum.02700-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/22/2022] [Indexed: 01/04/2023] Open
Abstract
In the current scenario of growing antibiotic resistance, understanding the interplay between resistance mechanisms and biological costs is crucial for designing therapeutic strategies. In this regard, intrinsic AmpC β-lactamase hyperproduction is probably the most important resistance mechanism of Pseudomonas aeruginosa, proven to entail important biological burdens that attenuate virulence mostly under peptidoglycan recycling alterations. P. aeruginosa can acquire resistance to new β-lactam-β-lactamase inhibitor combinations (ceftazidime-avibactam and ceftolozane-tazobactam) through mutations affecting ampC and its regulatory genes, but the impact of these mutations on the associated biological cost and the role that β-lactamase activity plays per se in contributing to the above-mentioned virulence attenuation are unknown. The same questions remain unsolved for plasmid-encoded AmpC-type β-lactamases such as FOX enzymes, some of which also provide resistance to new β-lactam-β-lactamase inhibitor combinations. Here, we assessed from different perspectives the effects of changes in the active center and, thus, in the hydrolytic spectrum resistance to inhibitors of AmpC-type β-lactamases on the fitness and virulence of P. aeruginosa, using site-directed mutagenesis; the previously described AmpC variants T96I, G183D, and ΔG229-E247; and, finally, blaFOX-4 versus blaFOX-8. Our results indicate the essential role of AmpC activity per se in causing the reported full virulence attenuation (in terms of growth, motility, cytotoxicity, and Galleria mellonella larvae killing), although the biological cost of the above-mentioned AmpC-type variants was similar to that of the wild-type enzymes. This suggests that there is not an important biological burden that may limit the selection/spread of these variants, which could progressively compromise the future effectiveness of the above-mentioned drug combinations. IMPORTANCE The growing antibiotic resistance of the top nosocomial pathogen Pseudomonas aeruginosa pushes research to explore new therapeutic strategies, for which the resistance-versus-virulence balance is a promising source of targets. While resistance often entails significant biological costs, little is known about the bases of the virulence attenuations associated with a resistance mechanism as extraordinarily relevant as β-lactamase production. We demonstrate that besides potential energy and cell wall alterations, the enzymatic activity of the P. aeruginosa cephalosporinase AmpC is essential for causing the full attenuation associated with its hyperproduction by affecting different features related to pathogenesis, a fact exploitable from the antivirulence perspective. Less encouraging, we also show that the production of different chromosomal/plasmid-encoded AmpC derivatives conferring resistance to some of the newest antibiotic combinations causes no significantly increased biological burdens, which suggests a free way for the selection/spread of these types of variants, potentially compromising the future effectiveness of these antipseudomonal therapies.
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Affiliation(s)
- Isabel M. Barceló
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Elena Jordana-Lluch
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
| | - María Escobar-Salom
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Gabriel Torrens
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Pablo A. Fraile-Ribot
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Gabriel Cabot
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Xavier Mulet
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Laura Zamorano
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Carlos Juan
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
| | - Antonio Oliver
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Microbiology Department, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas, Madrid, Spain
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