ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Antimicrobials, Resistance and Chemotherapy
This article is part of the Research TopicExpanding Multidisciplinary Potential of Cold Atmospheric Plasma Beyond Antimicrobial ResistanceView all 3 articles
Argon Plasma-Activated Liquid Inactivates Helicobacter Pylori and Resistant Hospital Pathogens Through Acidification and Reactive Species
Provisionally accepted
Leander Heisterberg1,2,3*
Ulrich Biber1Christopher Thompson2,3Alexander Neugebauer1
Jan Liese4Markus Enderle1Sebastian Grashorn4- 1Erbe Elektromedizin GmbH, Tübingen, Germany
- 2Brigham and Women's Hospital, Boston, United States
- 3Harvard Medical School, Boston, United States
- 4Eberhard Karls Universitat Tubingen Institut fur Medizinische Mikrobiologie und Hygiene, Tübingen, Germany
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Background: The rise of antibiotic-resistant bacteria is a major public health concern. Physical plasma can generate reactive oxygen and nitrogen species (RONS) with antimicrobial activity. Plasma-activated liquid (PAL) can be used as a carrier for RONS. This study investigated the antibacterial effects of PAL against clinically relevant Gram-negative (Escherichia coli, multidrug-resistant (MDR) Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumoniae, and Helicobacter pylori) and Gram-positive (Staphylococcus aureus and Enterococcus faecium) bacteria. Methods and Results: A commercial argon plasma electrosurgical source was used to produce PAL from 0.9% NaCl solution. PAL-NaCl showed strong bactericidal effects: MDR E. coli was completely eradicated (>6 log10 reduction) within 60 minutes. H. pylori was reduced by ~4.5 log10 within 15 minutes and completely eradicated (>5 log10) within 60 minutes of exposure. Gram-negative bacteria were highly susceptible with a mean reduction of ~6.3 log10, whereas Gram-positive bacteria showed lower susceptibility with a mean reduction of ~2.6 log10. Antibacterial activity was associated with acidic pH and influenced by carrier solution chemistry, consistent with a contribution of short-lived secondary reactive nitrogen species. The scavenger 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron(III) chloride (FeTPPS), targeting peroxynitrite (ONOO-), partially inhibited the antibacterial effect, supporting its mechanistic importance. Buffered solutions (higher pH) showed minimal antibacterial activity despite higher absolute RONS concentrations which underlines the importance of the acidic environment. Conclusions: PAL generated with an argon plasma electrosurgical source exhibits potent antibacterial activity, driven by low pH and RONS dynamics. PAL effectively inactivates MDR pathogens and other clinically relevant pathogens, including H. pylori. The stomach's acidic environment may enhance PAL activity by maintaining the low-pH conditions required for pH-dependent reactive nitrogen chemistry associated with antibacterial efficacy.
Keywords: cold plasma, Helicobacter, microbial biotechnology, Multidrug-resistant bacteria, novel antimicrobials, plasma activated liquid
Received: 19 Dec 2025; Accepted: 02 Feb 2026.
Copyright: © 2026 Heisterberg, Biber, Thompson, Neugebauer, Liese, Enderle and Grashorn. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Leander Heisterberg
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