Zinc and PBT2 breaking down bacterial resistance.

Zinc and PBT2: The Dynamic Duo that Could Beat Antibiotic Resistance

Theo Raines monogram
Theo Raines in Health & Wellness October 2026 • 3 min read.

"Can a novel combination of zinc and an ionophore called PBT2 offer a new approach to tackling resistant bacteria?"


Antibiotic resistance is an escalating global crisis, threatening to render common infections untreatable. The rise of 'superbugs' resistant to last-line antibiotics, coupled with a decline in new antibiotic development, demands innovative therapeutic strategies.

Researchers are exploring the potential of existing drugs initially developed for other conditions to combat bacterial resistance. One promising candidate is PBT2, a zinc ionophore tested in clinical trials for Alzheimer's and Huntington's disease.

A new study reveals the synergistic power of combining PBT2 with zinc to disrupt cellular homeostasis in resistant bacteria, effectively reversing antibiotic resistance in critical pathogens. This approach offers a new avenue for tackling antibiotic resistance, potentially revitalizing the effectiveness of existing treatments.

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The Growing AMR Burden

In the United States, more than 2.8 million antimicrobial-resistant infections occur each year. Globally, antibiotic resistance rose in over 40% of the pathogen-antibiotic combinations monitored between 2018 and 2023. A 2024 analysis estimated that bacterial antimicrobial resistance was associated with 4.71 million deaths in 2021, including 1.14 million deaths directly attributable to it.

Limits of Conventional Detection

PCR-based methods are widely used to detect antibiotic-resistance genes, but they may not identify unknown or novel genes and depend on the availability of suitable targets. Genetic approaches can also have low sensitivity and a narrow scope, potentially missing important AMR genes. These limitations help explain why resistance detection remains incomplete even as molecular testing advances.

Resistance Through History

Antibiotic resistance has deep evolutionary roots: the ancestor of hospital-associated enterococci dates back approximately 450 million years. In 1961, the first reports of methicillin-resistant Staphylococcus aureus appeared, followed in 1967 by reports of penicillin-resistant Streptococcus pneumoniae. In 1940, Oxford biochemists Edward Abraham and Ernst Chain reported an enzyme isolated from penicillin-resistant bacteria, an early milestone in understanding biological resistance mechanisms.

How PBT2 and Zinc Team Up Against Superbugs

Zinc and PBT2 breaking down bacterial resistance.

PBT2 is an ionophore, a molecule that facilitates the transport of ions across cell membranes. In this case, PBT2 helps zinc ions enter bacterial cells, disrupting their metal homeostasis. Bacteria carefully regulate the levels of metal ions inside their cells, and disrupting this balance can be toxic.

The study focused on Gram-positive bacteria, including:

  • Erythromycin-resistant group A Streptococcus (GAS)
  • Methicillin-resistant Staphylococcus aureus (MRSA)
  • Vancomycin-resistant Enterococcus (VRE)
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PBT2 and Zinc Synergy

Research on the ionophore PBT2 has examined its ability to work with zinc against resistant bacteria. A 2018 study reported that PBT2, described as safe for human use, displayed antibacterial activity in combination with zinc and at subinhibitory concentrations. The same research reported that PBT2 plus zinc disrupted cellular homeostasis in erythromycin-resistant group A Streptococcus, while a 2020 study investigated whether PBT2 could restore antibiotic sensitivity in polymyxin-resistant and ESBL-producing bacteria.

Why Treatment Can Fail

Antibiotic resistance means that bacteria change so antibiotic medicines can no longer kill them or stop their growth. If antibiotics and antifungals lose effectiveness, clinicians lose important tools for treating infections and controlling public-health threats. In addition, antibiotic concentrations that are too low can contribute to treatment failure and may fuel further resistance development.

A Different Route to Sensitivity

Antibiotic resistance can arise through changes in penicillin-binding proteins, including alterations in their structure or quantity. PBT2 offers a different strategy in the studies summarized here: it can increase antibiotic sensitivity, and combinations with gentamicin were associated with zinc influx and depletion. Other alternatives, such as antimicrobial peptides, are being studied because they can act at multiple intracellular target sites.

These pathogens are significant threats in both community and hospital settings, known for their resistance to multiple antibiotics. Researchers found that PBT2-zinc, while not potent on its own, significantly enhanced the effectiveness of several antibiotics against these resistant strains. Moreover, they observed no development of resistance to the PBT2-zinc combination, suggesting a durable therapeutic strategy.

A New Hope for Fighting Resistant Infections

The study highlights a novel approach to combating antibiotic resistance: disrupting bacterial physiology to resensitize pathogens to existing drugs. By destabilizing metal ion homeostasis, PBT2-zinc weakens bacteria and allows antibiotics to regain their effectiveness.

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A Multidimensional Threat

Antimicrobial resistance is described as a critical healthcare issue affecting mortality, quality of services, and financial damage. Assessing the possibility of pan-drug resistance requires more than a single forecast: one UK risk assessment used a Bayesian approach that combined available data with expert prior opinion. This framing supports treating AMR as both a clinical problem and a risk-management challenge.

Diagnostics and New Markets

The global antibiotic-resistance market is projected to grow from a likely US$12.1 billion in 2026 to US$17.5 billion by 2033. Proposed directions for changing resistance trends include faster diagnostics, expansion beyond traditional antibiotics, and greater attention to antimicrobial resistance outside hospitals. Detection technologies remain important because antibiotic resistance continues to threaten the effectiveness of antibiotic treatment.

Resistance Beyond the Hospital

Antibiotic-resistant bacteria account for over 25% of nosocomial infections, according to the cited 2025 review. That burden makes resistant bacteria a continuing challenge for healthcare systems rather than an isolated laboratory concern. The scale of hospital-associated infections also underscores why new approaches to prevention and treatment must fit within broader health-system responses.

Lives and Vulnerable Populations

A large study estimated that antibiotic-resistant bacterial infections directly caused 1.27 million deaths in 2019. Research on emerging antibiotic-resistant tuberculosis has also highlighted that the risk can be meaningfully altered in highly AIDS-immunocompromised populations. These findings illustrate how resistance affects both population-level mortality and people whose immune status increases their vulnerability.

While further research is needed to fully understand the mechanisms and optimize the use of PBT2-zinc, these findings offer a promising new strategy for tackling the growing threat of antibiotic resistance.

With PBT2 already proven safe for human use in other clinical trials, this research paves the way for potential new treatments that could significantly impact global healthcare and reduce the burden of resistant infections.

What a mouse wound study can establish

Animal study (level 5 of 8)

The study tested PBT2-zinc with antibiotics in a murine wound infection model, so its results show effects in that experimental setting, not whether the combinations work in people. The tested population included three resistant bacterial strains; the card also lists human primary tonsil epithelial cells, but the reported infection-burden findings concern the mouse model.[1] [2]

What keeps the result from being settled

  • The tested resistant GAS, MRSA, and VRE strains were specific isolates, so the findings do not establish the same response across all strains.[1] [2]
  • Erythromycin resistance was reversed in MRSA but not in GAS, showing that the effect was not consistent across bacteria.[1]
  • Visible cell-wall changes differed: GAS and MRSA showed none, while VRE developed depressions and later enlargement.[1]

PBT2-zinc and antibiotics in a murine wound model

Study designAnimal study[2]
PopulationGAS strain HKU16, MRSA strain USA300, VRE clinical isolate RBWH1, and human primary tonsil epithelial cells[2]
Settingmurine wound infection model[2]
Duration30 days[2]
ComparisonPBT2 or zinc alone; antibiotic alone[2]
Effect sizePBT2-zinc and antibiotics significantly reduced bacterial infection burden[2]
FundingNational Health and Medical Research Council of Australia[2]
Times cited76[2]

Questions the experiments leave open

  • Would the antibiotic pairings reduce infection burden beyond the tested resistant strains and the murine wound setting?[1] [2]
  • What molecular events connect increased bacterial zinc to the different antibiotic responses, given that the killing mechanism remains unresolved?[1] [3]

Terms used in the study

Bactericidal
Describes an effect that kills bacteria.[1]

Sources

  1. Chemical Synergy between Ionophore PBT2 and Zinc Reverses Antibiotic Resistance (Europe PMC, 2018)
  2. Chemical Synergy between Ionophore PBT2 and Zinc Reverses Antibiotic Resistance (American Society for Microbiology, 2018)
  3. Multiple Bactericidal Mechanisms of the Zinc Ionophore PBT2 (pmc.ncbi.nlm.nih.gov)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1128/mbio.02391-18, Alternate LINK

Title: Chemical Synergy Between Ionophore Pbt2 And Zinc Reverses Antibiotic Resistance

Subject: Virology

Journal: mBio

Publisher: American Society for Microbiology

Authors: Lisa Bohlmann, David M. P. De Oliveira, Ibrahim M. El-Deeb, Erin B. Brazel, Nichaela Harbison-Price, Cheryl-Lynn Y. Ong, Tania Rivera-Hernandez, Scott A. Ferguson, Amanda J. Cork, Minh-Duy Phan, Amelia T. Soderholm, Mark R. Davies, Graeme R. Nimmo, Gordon Dougan, Mark A. Schembri, Gregory M. Cook, Alastair G. Mcewan, Mark Von Itzstein, Christopher A. Mcdevitt, Mark J. Walker

Published: 2018-12-21

Everything You Need To Know

1

How does combining zinc with PBT2 help in overcoming antibiotic resistance in superbugs?

The combination of zinc and PBT2 works by using PBT2, an ionophore, to transport zinc ions into bacterial cells. This influx of zinc disrupts the bacteria's metal homeostasis, which is the careful balance of metal ions inside the cell that is crucial for bacterial survival. By disrupting this balance, the bacteria are weakened, making them more susceptible to antibiotics.

2

What exactly is PBT2, and what was its original purpose before being explored for antibiotic resistance?

PBT2 is a zinc ionophore initially developed and tested in clinical trials for conditions like Alzheimer's and Huntington's disease. Its role is to facilitate the transport of zinc ions across cell membranes, specifically into bacterial cells. This action disrupts the bacteria's internal metal ion balance, leading to weakened resistance against antibiotics. PBT2's previous testing for other conditions suggests a level of safety for human use, making it a promising candidate in the fight against antibiotic resistance.

3

Which specific types of antibiotic-resistant bacteria are affected by the zinc and PBT2 combination?

The study specifically targeted Gram-positive bacteria known for their resistance to multiple antibiotics. These included Erythromycin-resistant group A Streptococcus (GAS), Methicillin-resistant Staphylococcus aureus (MRSA), and Vancomycin-resistant Enterococcus (VRE). These pathogens pose significant threats in both community and hospital settings. The PBT2-zinc combination was effective in enhancing the impact of existing antibiotics against these resistant strains.

4

Why is disrupting metal ion homeostasis a promising strategy for fighting antibiotic resistance?

Disrupting metal ion homeostasis in bacteria offers a novel approach to combating antibiotic resistance because it weakens the bacteria's defenses, making them more susceptible to existing antibiotics. This strategy can potentially resensitize pathogens to drugs that were previously ineffective due to resistance mechanisms. By focusing on bacterial physiology rather than directly targeting specific bacterial functions, this approach may also prove more durable, as it doesn't rely on traditional antibiotic mechanisms that bacteria can easily develop resistance to.

5

Is there any evidence to suggest that bacteria will not develop resistance to the PBT2 and zinc combination over time?

The research indicated that the combination of PBT2 and zinc did not lead to the development of resistance in the tested bacteria. This is a significant finding because it suggests that this therapeutic strategy could offer a more durable solution compared to traditional antibiotics, where resistance often develops rapidly. The absence of resistance development with the PBT2-zinc combination implies that it could be a valuable tool in the long-term fight against antibiotic-resistant infections.

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