What probiotic kills Klebsiella pneumoniae? An investigation into probiotic strategies

October 4, 2025 •

4 min read

With antibiotic-resistant pathogens on the rise, including Klebsiella pneumoniae, alternative therapies are gaining significant attention. This has led researchers to investigate what probiotic kills Klebsiella pneumoniae, focusing on beneficial bacteria that can inhibit its growth and colonization.

Quick Summary

Several probiotic strains, particularly certain Lactobacillus and Bifidobacterium species, demonstrate an inhibitory effect on Klebsiella pneumoniae. Their mechanisms include producing antimicrobial compounds, modulating the immune system, and competing for resources within the gut microbiome. Probiotics offer a promising adjunctive strategy against this opportunistic pathogen.

Key Points

Probiotics vs. Antibiotics: Specific probiotic strains, primarily from the Lactobacillus and Bifidobacterium genera, inhibit Klebsiella pneumoniae, but are not a replacement for antibiotics for severe infections.
Specific Strains: Lactobacillus plantarum LP1812, L. rhamnosus CRL1505, and Bifidobacterium longum 51A and FB1-1 have demonstrated inhibitory effects in studies.
Antimicrobial Production: Some probiotics produce organic acids like acetic acid and protein-based bacteriocins that create an unfavorable environment for K. pneumoniae growth.
Immune System Modulation: Probiotics can enhance the host's immune response, including the production of anti-inflammatory cytokines, which helps in controlling infections both in the gut and respiratory tract.
Biofilm and Plasmid Inhibition: Probiotic action can inhibit the formation of protective biofilms by K. pneumoniae and interfere with the transfer of antibiotic resistance genes between bacteria.
Adjunctive Therapy: Probiotics are best viewed as a supportive therapy to be used alongside conventional medical treatment to restore the gut microbiome, not as a standalone cure.
Strain Specificity: The beneficial effects of probiotics are strain-dependent; research on one strain's effect on K. pneumoniae does not guarantee similar results from another.

The Rise of Antibiotic Resistance and Alternative Solutions

Klebsiella pneumoniae is a common and opportunistic gram-negative pathogen that can cause severe infections, particularly in hospital settings. The emergence and spread of multidrug-resistant (MDR) and carbapenem-resistant (CRKP) strains have created an urgent need for new therapeutic approaches. In this landscape, probiotics—live microorganisms that offer health benefits to the host—are emerging as a promising alternative or complementary strategy to conventional antibiotic treatments. Instead of directly 'killing' K. pneumoniae, specific probiotics employ a multifaceted approach, including producing inhibitory substances, modulating the host's immune response, and outcompeting the pathogen in the gut.

How Probiotics Inhibit Klebsiella pneumoniae

Probiotics leverage several mechanisms to counter the threat of K. pneumoniae colonization and infection. The efficacy can depend heavily on the specific strain, dosage, and delivery method.

Production of Antimicrobial Compounds

One of the primary ways certain probiotic strains combat K. pneumoniae is by producing substances that are toxic or inhibitory to the pathogen. For instance, many Lactobacillus strains produce organic acids, primarily lactic and acetic acids, which lower the local pH and create an unfavorable growth environment for K. pneumoniae.

Acetic Acid: A study showed that Lactobacillus plantarum LP1812 eradicated CRKP strains in vitro and significantly enhanced CRKP clearance in mice by increasing the intestinal concentration of acetic acid, which acidifies the pathogen's intracellular environment.
Bacteriocins: Some lactobacilli, including L. delbrueckii subsp. delbrueckii LDD01, produce bacteriocins—proteins with antibacterial activity—that can specifically target and inhibit K. pneumoniae.

Immune System Modulation

Probiotics can influence the host's immune system, strengthening its ability to fight infections both in the gut and in extra-intestinal sites like the lungs. This is part of the concept of the 'gut-lung axis'.

Bifidobacterium longum 51A: Oral treatment with this strain in a mouse model of pneumonia significantly reduced bacterial load in the lungs, decreased lung damage, and increased the production of the anti-inflammatory cytokine IL-10.
Lactobacillus rhamnosus CRL1505: In another mouse study, this strain improved resistance to hypermucoviscous CRKP ST25 strains by modulating the respiratory innate immune response, reducing inflammatory cytokines and increasing regulatory cytokines.

Competitive Exclusion and Biofilm Inhibition

Probiotic bacteria compete with pathogens for resources and attachment sites, preventing colonization. They also disrupt the pathogen's ability to form biofilms, which are dense bacterial communities that confer resistance to antibiotics and the immune system.

Competition for Resources: Healthy gut microbiota, often rich in certain Bacteroidota species, can limit K. pneumoniae colonization by competing for ecological niches.
Biofilm Disruption: Co-culturing probiotics like L. rhamnosus and L. sake has been shown to inhibit biofilm formation by K. pneumoniae.

Inhibition of Plasmid Transfer

Some probiotics can interfere with the horizontal gene transfer of antibiotic resistance plasmids, a major factor in the spread of CRKP. For example, the cell-free supernatant (CFS) of Bifidobacterium longum FB1-1 was found to inhibit the transfer of the blaKPC plasmid in CRKP.

Specific Probiotic Strains with Activity Against K. pneumoniae

Based on preclinical research, several specific probiotic strains have demonstrated notable activity against K. pneumoniae. The following table summarizes some of the most promising candidates and their mechanisms.

Comparison of Probiotic Strains and Their Actions Against K. pneumoniae


Probiotic Strain	Mechanism of Action	Study Context	Key Finding	Citation
Lactiplantibacillus plantarum LP1812	Produces acetic acid to inhibit growth; modulates intestinal microbiota.	In vitro & in vivo (mouse)	Eradicated CRKP in vitro and significantly reduced CRKP colonization in mice.
Bifidobacterium longum 51A	Immunomodulation via the gut-lung axis; increases anti-inflammatory IL-10.	In vivo (mouse)	Reduced lung damage, bacterial load, and mortality in mouse pneumonia model.
Lactobacillus rhamnosus B-445	Secretes antimicrobial compounds (bacteriocins); competes for resources.	In vitro	Showed significant inhibitory effect against clinical MDR K. pneumoniae isolates.
Lactobacillus delbrueckii subsp. delbrueckii LDD01	Produces bacteriocin, a protein with antibacterial properties.	In vitro	Demonstrated the best inhibitory results among tested strains against K. pneumoniae.
Bifidobacterium longum FB1-1 (Cell-Free Supernatant)	Inhibits plasmid transfer and downregulates virulence genes.	In vitro	Markedly reduced expression of blaKPC and virulence genes in CRKP.

Probiotics as Adjunct Therapy and Future Directions

It is crucial to understand that probiotics are not a direct replacement for antibiotics, especially in treating severe, established infections. However, they hold significant promise as an adjunct therapy, particularly for high-risk patients such as those in intensive care units. Probiotics can support treatment by mitigating the gut microbiome dysbiosis caused by antibiotics and by enhancing the host's natural defenses.

Importance of Clinical Studies

While animal studies and in vitro experiments have provided compelling evidence, more large-scale, well-designed human clinical trials are needed to confirm these effects and determine the most effective strains, dosages, and administration protocols for specific patient populations. The strain-specific nature of probiotic effects means that what works for one probiotic may not work for another.

Restoring Microbiome Health

For critically ill patients, gut microbiota dysbiosis is a significant risk factor for subsequent infections. Strategies aimed at restoring a healthy gut microbiome, potentially using probiotics or even fecal microbiota transplantation (FMT), are being explored to increase resistance to colonization by pathogens like CRKP. A healthy gut ecosystem can, in turn, influence immunity far beyond the intestinal tract, offering a systemic protective effect.

Conclusion

While no single probiotic can be definitively labeled as a 'killer' of Klebsiella pneumoniae, research clearly indicates that certain strains, notably species within the Lactobacillus and Bifidobacterium genera, possess powerful inhibitory properties. They achieve this through multiple mechanisms, including the production of organic acids and bacteriocins, immunomodulation via the gut-lung axis, and competitive exclusion. This evidence positions probiotics not as a cure-all, but as a valuable and promising tool in the fight against antibiotic-resistant pathogens. Continued research will help translate these promising findings into robust clinical strategies for preventing and managing infections caused by Klebsiella pneumoniae.

This article provides general information and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.

Frequently Asked Questions

No, probiotics are not a replacement for antibiotics. In severe, active infections like those caused by Klebsiella pneumoniae, antibiotic therapy is typically necessary. Probiotics should be considered as a complementary or adjunctive therapy, used to help restore healthy gut flora and support the immune system.

Probiotics fight K. pneumoniae through several mechanisms. They produce antimicrobial substances like organic acids and bacteriocins, modulate the host immune system to reduce inflammation, and competitively exclude the pathogen by taking up space and nutrients in the gut.

Research has identified several specific strains with inhibitory effects, including Lactobacillus plantarum LP1812, Lactobacillus rhamnosus CRL1505, and Bifidobacterium longum strains like 51A and FB1-1. Effects are highly strain-specific and often demonstrated in laboratory or animal studies.

Yes, some probiotics have been shown to have an effect on CRKP. For example, Lactobacillus plantarum LP1812 has shown effectiveness against CRKP in lab and animal models. Additionally, the cell-free supernatant of Bifidobacterium longum FB1-1 can inhibit plasmid transfer, a mechanism by which bacteria share resistance genes.

While generally safe, it is important to discuss this with a healthcare provider, especially for critically ill or immunocompromised patients. Taking certain probiotics in conjunction with antibiotics can help prevent antibiotic-associated diarrhea and support the gut microbiome, but timing may be important to ensure probiotic survival.

The 'gut-lung axis' refers to the communication pathway between the gut and the lungs. A healthy gut microbiome, supported by probiotics, can modulate the immune response in the respiratory tract. Research shows that probiotics can reduce lung inflammation and increase resistance to respiratory infections, including those caused by K. pneumoniae.

A diet rich in probiotic-containing foods and prebiotic fibers can support a healthy gut microbiome, which in turn strengthens the body's natural defenses against opportunistic pathogens like K. pneumoniae. Examples include fermented foods like yogurt and kefir, along with fibrous vegetables.

An in vitro study is conducted in a lab setting, such as in a test tube or petri dish, and shows a direct interaction between the probiotic and the pathogen. An in vivo study involves living organisms, like mice, and provides insight into how the probiotic affects the infection and immune system within a complex biological system.