Bacteria-Killing Viruses Plus Probiotics: A New Way to Fight Food Poisoning Without Antibiotics

Researchers have found a powerful new strategy to combat drug-resistant food poisoning: combining bacteria-killing viruses with beneficial probiotics. In a study using chickens infected with multidrug-resistant Salmonella, the combination therapy not only eliminated the dangerous bacteria more effectively than either treatment alone but also restored gut health and improved overall recovery. This breakthrough offers hope for controlling foodborne illness in poultry production without relying on antibiotics, which have fueled the rise of drug-resistant bacteria.

Why Is This Discovery Important for Food Safety?

Salmonella remains one of the leading causes of foodborne illness worldwide, with poultry products serving as a major transmission route to humans. The problem has grown worse because widespread antibiotic use in poultry farming has created multidrug-resistant Salmonella strains that no longer respond to conventional treatments. Many countries have already banned antibiotic growth promoters in livestock, making alternative strategies urgent.

The new approach uses two distinct tools working together. Bacteriophages—viruses that selectively infect and kill specific bacteria—rapidly reduce pathogenic Salmonella populations. Probiotics, specifically beneficial bacteria like Limosilactobacillus reuteri, then help stabilize the gut community and prevent the pathogen from returning. This one-two punch addresses a major limitation of phage therapy alone: bacteria can develop resistance to the viruses over time.

What Did the Research Show?

Scientists tested the combination therapy in chickens challenged with Salmonella enterica serovar Typhimurium infection. The study compared three groups: phage treatment alone, probiotic treatment alone, and the combination of two bacteriophages (SLAM_phiST45 and SLAM_phiST56) plus the probiotic strain SLAM_LAR11.

The results were striking. Compared to phage-only treatment, the combined therapy delivered measurable improvements across multiple health markers:

• Body Weight Recovery: Chickens receiving the combination therapy showed significantly improved weight gain from infection to recovery, with a statistically significant difference (p<0.0001), meaning researchers were over 99% certain this improvement was real and not due to chance.
• Organ Health: The combination therapy reduced infection-related swelling of the spleen (splenomegaly) by a statistically significant margin (p=0.028) and liver enlargement (hepatomegaly) by a significant difference (p=0.011), indicating less systemic inflammation.
• Intestinal Barrier Strength: In the small intestine (ileum), the ratio of villus height to crypt depth—a key measure of intestinal tissue health—increased significantly (p=0.044), meaning the gut lining was better preserved.
• Gut Barrier Genes: In the colon, expression of tight-junction genes that seal the intestinal barrier increased significantly, including OCLN (p=0.014), TJP1 (p<0.0001), and MUC2 (p=0.011), which produces protective mucus.
• Reduced Inflammation: Pro-inflammatory cytokine IL-6, a marker of harmful immune activation, was significantly reduced (p=0.018) in the colon, suggesting less intestinal damage.

How Does the Combination Restore Healthy Gut Bacteria?

Beyond eliminating the pathogen, the combination therapy reshaped the gut microbiome in ways that favor long-term health. In the small intestine, beneficial bacteria including Lactobacillus and Blautia increased significantly (p=0.037 and p=0.016, respectively), creating a more balanced microbial community than phage treatment alone achieved.

This microbial rebalancing had a direct metabolic benefit. Levels of short-chain fatty acids—particularly acetic acid and lactic acid—increased substantially. These organic acids are crucial for intestinal health, immune function, and preventing harmful bacteria from colonizing the gut. The combination therapy essentially restored the gut's natural chemistry in addition to eliminating the infection.

"Phage-probiotic co-administration not only enhances the clearance of multidrug-resistant Salmonella more effectively than phage treatment alone but also promotes intestinal health, highlighting its potential as an antibiotic-alternatives strategy," the research team concluded. This dual benefit—pathogen elimination plus gut restoration—distinguishes the combination approach from either treatment used independently.

What Makes This an Antibiotic Alternative?

Traditional antibiotics kill a broad spectrum of bacteria, which can devastate the beneficial microbes that protect gut health. Bacteriophages, by contrast, target only specific pathogenic bacteria, leaving beneficial species largely untouched. When combined with probiotics that actively restore healthy bacterial populations, the result is pathogen control without the collateral damage of conventional antibiotics.

This approach addresses a critical public health challenge: the emergence of multidrug-resistant bacteria. By avoiding broad-spectrum antibiotics, phage-probiotic therapy reduces the selective pressure that drives antibiotic resistance. As countries increasingly restrict antibiotic use in livestock, this strategy offers a practical, science-backed alternative that maintains food safety while protecting the long-term effectiveness of antibiotics for human medicine.

While this research was conducted in chickens, the mechanisms involved—how bacteriophages eliminate pathogens and how probiotics restore microbial balance—are fundamental to how gut bacteria work across species. The findings suggest that phage-probiotic combinations could eventually offer benefits for human foodborne illness prevention and treatment, though human studies would be needed to confirm safety and efficacy in people.