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Maybin JA, Thompson TP, Flynn PB, Skvortsov T, Hickok NJ, Freeman TA, Gilmore BF. Cold atmospheric pressure plasma-antibiotic synergy in Pseudomonas aeruginosa biofilms is mediated via oxidative stress response. Biofilm 2023; 5:100122. [PMID: 37214348 PMCID: PMC10196807 DOI: 10.1016/j.bioflm.2023.100122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 05/24/2023] Open
Abstract
Cold atmospheric-pressure plasma (CAP) has emerged as a potential alternative or adjuvant to conventional antibiotics for the treatment of bacterial infections, including those caused by antibiotic-resistant pathogens. The potential of sub-lethal CAP exposures to synergise conventional antimicrobials for the eradication of Pseudomonas aeruginosa biofilms is investigated in this study. The efficacy of antimicrobials following or in the absence of sub-lethal CAP pre-treatment in P. aeruginosa biofilms was assessed. CAP pre-treatment resulted in an increase in both planktonic and biofilm antimicrobial sensitivity for all three strains tested (PAO1, PA14, and PA10548), with both minimum inhibitory concentrations (MICs) and minimum biofilm eradication concentrations (MBECs) of individual antimicrobials, being significantly reduced following CAP pre-treatment of the biofilm (512-fold reduction with ciprofloxacin/gentamicin; and a 256-fold reduction with tobramycin). At all concentrations of antimicrobial used, the combination of sub-lethal CAP exposure and antimicrobials was effective at increasing time-to-peak metabolism, as measured by isothermal microcalorimetry, again indicating enhanced susceptibility. CAP is known to damage bacterial cell membranes and DNA by causing oxidative stress through the in situ generation of reactive oxygen and nitrogen species (RONS). While the exact mechanism is not clear, oxidative stress on outer membrane proteins is thought to damage/perturb cell membranes, confirmed by ATP and LDH leakage, allowing antimicrobials to penetrate the bacterial cell more effectively, thus increasing bacterial susceptibility. Transcriptomic analysis, reveals that cold-plasma mediated oxidative stress caused upregulation of P. aeruginosa superoxide dismutase, cbb3 oxidases, catalases, and peroxidases, and upregulation in denitrification genes, suggesting that P. aeruginosa uses these enzymes to degrade RONS and mitigate the effects of cold plasma mediated oxidative stress. CAP treatment also led to an increased production of the signalling molecule ppGpp in P. aeruginosa, indicative of a stringent response being established. Although we did not directly measure persister cell formation, this stringent response may potentially be associated with the formation of persister cells in biofilm cultures. The production of ppGpp and polyphosphate may be associated with protein synthesis inhibition and increase efflux pump activity, factors which can result in antimicrobial tolerance. The transcriptomic analysis also showed that by 6 h post-treatment, there was downregulation in ribosome modulation factor, which is involved in the formation of persister cells, suggesting that the cells had begun to resuscitate/recover. In addition, CAP treatment at 4 h post-exposure caused downregulation of the virulence factors pyoverdine and pyocyanin; by 6 h post-exposure, virulence factor production was increasing. Transcriptomic analysis provides valuable insights into the mechanisms by which P. aeruginosa biofilms exhibits enhanced susceptibility to antimicrobials. Overall, these findings suggest, for the first time, that short CAP sub-lethal pre-treatment can be an effective strategy for enhancing the susceptibility of P. aeruginosa biofilms to antimicrobials and provides important mechanistic insights into cold plasma-antimicrobial synergy. Transcriptomic analysis of the response to, and recovery from, sub-lethal cold plasma exposures in P. aeruginosa biofilms improves our current understanding of cold plasma biofilm interactions.
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Affiliation(s)
- Jordanne-Amee Maybin
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Thomas P Thompson
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Padrig B Flynn
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Timofey Skvortsov
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Noreen J Hickok
- Department of Orthopaedic Surgery Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Theresa A Freeman
- Department of Orthopaedic Surgery Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Brendan F Gilmore
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
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Kašparová P, Vaňková E, Paldrychová M, Svobodová A, Hadravová R, Jarošová Kolouchová I, Masák J, Scholtz V. Non-thermal plasma causes Pseudomonas aeruginosa biofilm release to planktonic form and inhibits production of Las-B elastase, protease and pyocyanin. Front Cell Infect Microbiol 2022; 12:993029. [PMID: 36211963 PMCID: PMC9544392 DOI: 10.3389/fcimb.2022.993029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
The increasing risk of antibiotic failure in the treatment of Pseudomonas aeruginosa infections is largely related to the production of a wide range of virulence factors. The use of non-thermal plasma (NTP) is a promising alternative to antimicrobial treatment. Nevertheless, there is still a lack of knowledge about the effects of NTP on the virulence factors production. We evaluated the ability of four NTP-affected P. aeruginosa strains to re-form biofilm and produce Las-B elastase, proteases, lipases, haemolysins, gelatinase or pyocyanin. Highly strains-dependent inhibitory activity of NTP against extracellular virulence factors production was observed. Las-B elastase activity was reduced up to 82% after 15-min NTP treatment, protease activity and pyocyanin production by biofilm cells was completely inhibited after 60 min, in contrast to lipases and gelatinase production, which remained unchanged. However, for all strains tested, a notable reduction in biofilm re-development ability was depicted using spinning disc confocal microscopy. In addition, NTP exposure of mature biofilms caused disruption of biofilm cells and their dispersion into the environment, as shown by transmission electron microscopy. This appears to be a key step that could help overcome the high resistance of P. aeruginosa and its eventual elimination, for example in combination with antibiotics still highly effective against planktonic cells.
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Affiliation(s)
- Petra Kašparová
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
- Laboratory of Non-thermal Plasma, Department of Physics and Measurements, University of Chemistry and Technology in Prague, Prague, Czechia
- *Correspondence: Petra Kašparová,
| | - Eva Vaňková
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
- Laboratory of Non-thermal Plasma, Department of Physics and Measurements, University of Chemistry and Technology in Prague, Prague, Czechia
| | - Martina Paldrychová
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
- Laboratory of Non-thermal Plasma, Department of Physics and Measurements, University of Chemistry and Technology in Prague, Prague, Czechia
| | - Alžběta Svobodová
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
| | - Romana Hadravová
- Viral and Microbial Proteins, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Irena Jarošová Kolouchová
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
| | - Jan Masák
- Laboratory of Applied Biology, Department of Biotechnology, University of Chemistry and Technology in Prague, Prague, Czechia
| | - Vladimir Scholtz
- Laboratory of Non-thermal Plasma, Department of Physics and Measurements, University of Chemistry and Technology in Prague, Prague, Czechia
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Scholtz V, Vaňková E, Kašparová P, Premanath R, Karunasagar I, Julák J. Non-thermal Plasma Treatment of ESKAPE Pathogens: A Review. Front Microbiol 2021; 12:737635. [PMID: 34712211 PMCID: PMC8546340 DOI: 10.3389/fmicb.2021.737635] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/09/2021] [Indexed: 01/19/2023] Open
Abstract
The acronym ESKAPE refers to a group of bacteria consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. They are important in human medicine as pathogens that show increasing resistance to commonly used antibiotics; thus, the search for new effective bactericidal agents is still topical. One of the possible alternatives is the use of non-thermal plasma (NTP), a partially ionized gas with the energy stored particularly in the free electrons, which has antimicrobial and anti-biofilm effects. Its mechanism of action includes the formation of pores in the bacterial membranes; therefore, resistance toward it is not developed. This paper focuses on the current overview of literature describing the use of NTP as a new promising tool against ESKAPE bacteria, both in planktonic and biofilm forms. Thus, it points to the fact that NTP treatment can be used for the decontamination of different types of liquids, medical materials, and devices or even surfaces used in various industries. In summary, the use of diverse experimental setups leads to very different efficiencies in inactivation. However, Gram-positive bacteria appear less susceptible compared to Gram-negative ones, in general.
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Affiliation(s)
- Vladimír Scholtz
- Department of Physics and Measurements, University of Chemistry and Technology, Prague, Czechia
| | - Eva Vaňková
- Department of Physics and Measurements, University of Chemistry and Technology, Prague, Czechia.,Department of Biotechnology, University of Chemistry and Technology, Prague, Czechia
| | - Petra Kašparová
- Department of Physics and Measurements, University of Chemistry and Technology, Prague, Czechia
| | - Ramya Premanath
- Nitte University, Nitte University Centre for Science Education and Research, Mangalore, India
| | - Iddya Karunasagar
- Nitte University, Nitte University Centre for Science Education and Research, Mangalore, India
| | - Jaroslav Julák
- Department of Physics and Measurements, University of Chemistry and Technology, Prague, Czechia.,Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czechia
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