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Harkova LG, de Dios R, Rubio-Valle A, Pérez-Pulido AJ, McCarthy RR. Cyclic AMP is a global virulence regulator governing inter and intrabacterial signalling in Acinetobacter baumannii. PLoS Pathog 2024; 20:e1012529. [PMID: 39241032 PMCID: PMC11410210 DOI: 10.1371/journal.ppat.1012529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 09/18/2024] [Accepted: 08/22/2024] [Indexed: 09/08/2024] Open
Abstract
Acinetobacter baumannii is an opportunistic nosocomial pathogen with high morbidity and mortality rates. Current treatment options for this pathogen are limited due to its increasing resistance to last-resort antibiotics. Despite A. baumannii's leading position in the World Health Organisations priority pathogens list, little is known about its virulence regulation. Through a high-throughput screening approach to identify novel biofilm regulators, we identified a previously uncharacterised predicted adenylate cyclase (AC), CavA, as a central regulator of this phenotype. cAMP is a crucial mediator of various aspects of bacterial physiology in other species but information about its role in A. baumannii is limited. We confirm that CavA AC is functional and synthesizes cAMP in A. baumannii. Using dRNA-seq, we verify that CavA is a negative biofilm formation regulator affecting Csu pili and exopolysaccharide production. We demonstrate for the first time that in A. baumannii, cAMP is atop of a hierarchical signalling cascade controlling inter- and intrabacterial signalling by modulating quorum sensing and cyclic di-GMP systems, ultimately governing virulence in vivo and adaptive antibiotic resistance. In contrast to the well-established paradigm in other bacteria where cAMP and cyclic di-GMP levels are inversely regulated, we uncover that the levels of these second messengers are directly proportional in A. baumannii. Overall, this study uncovers the central role of CavA and cAMP in the pathogenic success of A. baumannii and highlights this signalling cascade as a high potential target for novel therapeutic development.
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Affiliation(s)
- Lyuboslava G Harkova
- Antimicrobial Innovations Centre, Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Rubén de Dios
- Antimicrobial Innovations Centre, Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Alejandro Rubio-Valle
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-JA), Universidad Pablo de Olavide, Sevilla, Spain
| | - Antonio J Pérez-Pulido
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-JA), Universidad Pablo de Olavide, Sevilla, Spain
| | - Ronan R McCarthy
- Antimicrobial Innovations Centre, Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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Uc-Cachón AH, Dzul-Beh A, González-Cortázar M, Zamilpa-Álvarez A, Molina-Salinas GM. Investigating the anti-growth, anti-resistance, and anti-virulence activities of Schoepfia schreberi J.F.Gmel. against the superbug Acinetobacter baumannii. Heliyon 2024; 10:e31420. [PMID: 38813144 PMCID: PMC11133943 DOI: 10.1016/j.heliyon.2024.e31420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/31/2024] Open
Abstract
Schoepfia schreberi has been used in Mayan folk medicine to treat diarrhea and cough. This study aimed to determine the anti-growth, anti-resistance, and/or anti-virulence activities of S. schreberi extracts against Acinetobacter baumannii, a pathogen leader that causes healthcare-associated infections with high rates of drug-resistant including carbapenems, the last line of antibiotics known as superbugs, and analyze their composition using HPLC-DAD. Ethyl acetate (SSB-3) and methanol (SSB-4) bark extracts exhibit antimicrobial and biocidal effects against drug-susceptible and drug-resistant A. baumannii. Chemical analysis revealed that SSB-3 and SSB-4 contained of gallic and ellagic acids derivatives. The anti-resistance activity of the extracts revealed that SSB-3 or SSB-4, combined with imipenem, exhibited potent antibiotic reversal activity against A. baumannii by acting as pump efflux modulators. The extracts also displayed activity against surface motility of A. baumannii and its capacity to survive reactive oxygen species. This study suggests that S. schreberi can be considered a source of antibiotics, even adjuvanted compounds, as anti-resistant or anti-virulence agents against A. baumannii, contributing to ethnopharmacological knowledge and reappraisal of Mayan medicinal flora, and supporting the traditional use of the bark of the medicinal plant S. schreberi for the treatment of infectious diseases.
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Affiliation(s)
- Andrés Humberto Uc-Cachón
- Unidad de Investigación Médica Yucatán, Instituto Mexicano del Seguro Social, Mérida, 97150, Yucatán, Mexico
| | - Angel Dzul-Beh
- Unidad de Investigación Médica Yucatán, Instituto Mexicano del Seguro Social, Mérida, 97150, Yucatán, Mexico
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México, 11340, Mexico
| | - Manases González-Cortázar
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social, Xochitepec, 62790, Morelos, Mexico
| | - Alejandro Zamilpa-Álvarez
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social, Xochitepec, 62790, Morelos, Mexico
| | - Gloria María Molina-Salinas
- Unidad de Investigación Médica Yucatán, Instituto Mexicano del Seguro Social, Mérida, 97150, Yucatán, Mexico
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Gadar K, de Dios R, Kadeřábková N, Prescott TAK, Mavridou DAI, McCarthy RR. Disrupting iron homeostasis can potentiate colistin activity and overcome colistin resistance mechanisms in Gram-Negative Bacteria. Commun Biol 2023; 6:937. [PMID: 37704838 PMCID: PMC10499790 DOI: 10.1038/s42003-023-05302-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 08/29/2023] [Indexed: 09/15/2023] Open
Abstract
Acinetobacter baumannii is a Gram-negative priority pathogen that can readily overcome antibiotic treatment through a range of intrinsic and acquired resistance mechanisms. Treatment of carbapenem-resistant A. baumannii largely relies on the use of colistin in cases where other treatment options have been exhausted. However, the emergence of resistance against this last-line drug has significantly increased amongst clinical strains. In this study, we identify the phytochemical kaempferol as a potentiator of colistin activity. When administered singularly, kaempferol has no effect on growth but does impact biofilm formation. Nonetheless, co-administration of kaempferol with sub-inhibitory concentrations of colistin exposes bacteria to a metabolic Achilles heel, whereby kaempferol-induced dysregulation of iron homeostasis leads to bacterial killing. We demonstrate that this effect is due to the disruption of Fenton's reaction, and therefore to a lethal build-up of toxic reactive oxygen species in the cell. Furthermore, we show that this vulnerability can be exploited to overcome both intrinsic and acquired colistin resistance in clinical strains of A. baumannii and E. coli in vitro and in the Galleria mellonella model of infection. Overall, our findings provide a proof-of-principle demonstration that targeting iron homeostasis is a promising strategy for enhancing the efficacy of colistin and overcoming colistin-resistant infections.
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Affiliation(s)
- Kavita Gadar
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
| | - Rubén de Dios
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
| | - Nikol Kadeřábková
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Despoina A I Mavridou
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
- John Ring LaMontagne Centre for Infectious Diseases, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Ronan R McCarthy
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
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de Dios R, Proctor CR, Maslova E, Dzalbe S, Rudolph CJ, McCarthy RR. Artificial sweeteners inhibit multidrug-resistant pathogen growth and potentiate antibiotic activity. EMBO Mol Med 2023; 15:e16397. [PMID: 36412260 PMCID: PMC9832836 DOI: 10.15252/emmm.202216397] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 10/28/2022] [Accepted: 10/28/2022] [Indexed: 11/23/2022] Open
Abstract
Antimicrobial resistance is one of the most pressing concerns of our time. The human diet is rich with compounds that alter bacterial gut communities and virulence-associated behaviours, suggesting food additives may be a niche for the discovery of novel anti-virulence compounds. Here, we identify three artificial sweeteners, saccharin, cyclamate and acesulfame-K (ace-K), that have a major growth inhibitory effect on priority pathogens. We further characterise the impact of ace-K on multidrug-resistant Acinetobacter baumannii, demonstrating that it can disable virulence behaviours such as biofilm formation, motility and the ability to acquire exogenous antibiotic-resistant genes. Further analysis revealed the mechanism of growth inhibition is through bulge-mediated cell lysis and that cells can be rescued by cation supplementation. Antibiotic sensitivity assays demonstrated that at sub-lethal concentrations, ace-K can resensitise A. baumannii to last resort antibiotics, including carbapenems. Using a novel ex vivo porcine skin wound model, we show that ace-K antimicrobial activity is maintained in the wound microenvironment. Our findings demonstrate the influence of artificial sweeteners on pathogen behaviour and uncover their therapeutic potential.
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Affiliation(s)
- Rubén de Dios
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Chris R Proctor
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Evgenia Maslova
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Sindija Dzalbe
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Christian J Rudolph
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Ronan R McCarthy
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
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de Dios R, Gadar K, McCarthy RR. A high-efficiency scar-free genome-editing toolkit for Acinetobacter baumannii. J Antimicrob Chemother 2022; 77:3390-3398. [PMID: 36216579 PMCID: PMC9704439 DOI: 10.1093/jac/dkac328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 09/05/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The current mutagenesis tools for Acinetobacter baumannii leave selection markers or residual sequences behind, or involve tedious counterselection and screening steps. Furthermore, they are usually adapted for model strains, rather than for MDR clinical isolates. OBJECTIVES To develop a scar-free genome-editing tool suitable for chromosomal and plasmid modifications in MDR A. baumannii AB5075. METHODS We prove the efficiency of our adapted genome-editing system by deleting the multidrug efflux pumps craA, cmlA5 and resistance island 2 (RI2), as well as curing plasmid p1AB5075, and combining these mutations. We then characterized the susceptibility of the mutants compared with the WT to different antibiotics (i.e. chloramphenicol, amikacin and tobramycin) by disc diffusion assays and determined the MIC for each strain. RESULTS We successfully adapted the genome-editing protocol to A. baumannii AB5075, achieving a double recombination frequency close to 100% and routinely securing the construction of a mutant within 10 working days. Furthermore, we show that both CraA and p1AB5075 are involved in chloramphenicol resistance, and that RI2 and p1AB5075 play a role in resistance to amikacin and tobramycin. CONCLUSIONS We have developed a versatile and highly efficient genome-editing tool for A. baumannii. We have demonstrated it can be used to modify both the chromosome and native plasmids. By challenging the method, we show the role of CraA and p1AB5075 in antibiotic resistance.
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Affiliation(s)
- Rubén de Dios
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
| | - Kavita Gadar
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
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Sionov RV, Steinberg D. Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:1239. [PMID: 35744757 PMCID: PMC9228545 DOI: 10.3390/microorganisms10061239] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.
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Affiliation(s)
- Ronit Vogt Sionov
- The Biofilm Research Laboratory, The Institute of Biomedical and Oral Research, The Faculty of Dental Medicine, Hadassah Medical School, The Hebrew University, Jerusalem 9112102, Israel;
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