Next Generation Antibiotics:
Bacteriocins and Defensins: Postbiotic Metabolites That Fight Pathogens

Posted On: August 15, 2018
Categories: The Health Series,


The overuse and misuse of antibiotics has created a global health crisis

By Ross Pelton, RPh, PhD, CCN

Compounds named bacteriocinsi and defensinsii are postbiotic metabolites with antimicrobial activity. These compounds are small molecular weight proteins that are also referred to as antimicrobial peptides or AMPs.

Bacteriocins and defensins function as naturally produced antibiotics in the body and consequently, they are an important part of our human immune system.iii The importance of these antimicrobial postbiotic metabolites should not be underestimated. Scientists now realize that antimicrobial peptides (AMPs) are an infant’s first line of defense against infections.iv Similarly, throughout life, antimicrobial peptides, which are postbiotic metabolites produced by your probiotic bacteria, are now known to be a primary part of the first line of defense in the gastrointestinal tract of adults.v

However there are important differences between prescription drug antibiotics and these antimicrobial peptide compounds that are naturally produced by your probiotic bacteria.

Many prescription drug antibiotics are classified as broad-spectrum antibiotics, which means they kill a wide range of different types of bacteria. It is important to realize that prescription antibiotics do not discriminate between pathogens or “bad” bacteria and our beneficial probiotic bacteria. Prescription antibiotics can be compared to large military bombs, they kill almost everything and there is frequently a large amount of collateral damage.

Bacteriocins and defensins are unique in that they have a relatively narrow spectrum or range of activity. They are selectively active against pathogens but they do not harm your beneficial probiotic bacteria.

Antibiotic Resistant Superbugs

The overuse and misuse of antibiotics has created a global health crisis. The World Health Organization (WHO) has sounded the alarm announcing that the rapid rise of antibiotic resistant superbugs is a serious global threat to human Initially, the incidence of superbug infections occurred primarily in hospitals and nursing homes. However, we are now seeing a frightening increase in the incidence of community acquired superbug antibiotic resistant infections.vii

Dawn of the Post-Antibiotic Era

Many scientists from around the world are worried that humanity is entering a post-antibiotic era in which antibiotics will no longer be effective.viii In fact, in 2014, England’s Prime Minister commissioned a study titled: Review on Antimicrobial Resistance.ix In their conclusion, the authors of this review stated that if immediate action were not taken, by 2050, antibiotic-resistant superbugs would kill more people than cancer. We may be facing a future in which C-section births, joint replacements, organ transplants and even minor surgeries will no longer be possible because of the threat of infections without the availability of antibiotics.

In order to reverse this trend, we must teach people how to create and maintain a healthy microbiome because we now understand that your probiotic bacteria produce compounds that are the front line of your immune system. We desperately need more bugs and fewer drugs. But, taking probiotics is not enough. People must feed their probiotics well, or else they will not thrive and survive. In order to maintaining a healthy microbiome, people must consume a high fiber, plant-based diet.

In addition to the properties of antimicrobial peptides that have been discussed in this article, some AMPs have also been shown to have antifungalx and antiviralxi activity. It is becoming increasingly apparent that a healthy microbiome is the foundation of a healthy immune system. A healthy microbiome contains a diverse population of probiotic bacteria, which in turn will produce a diverse range of immune system-enhancing postbiotic antimicrobial peptides.

i Bondaryk M, et al. Natural Antimicrobial Peptides as Inspiration for Design of a New Generation Antifungal Compounds. Journal of Fungi. 2017;3(46):1-36.
ii Chikindas ML, et al. Functions and emerging applications of bacteriocins. Curr Opin Biotechnol. 2018 Feb;49:23-28.
iii Ghosh D. Probiotics and Intestinal Defensins: Augmenting the first line of defense in Gastrointestinal Immunity. In Probiotic Foods in Health and Disease. Editors G. Nair and Y. Takeda. 2010; 61-74. Oxford & IBH Publishing Co. Pvt. Ltd. New Delhi.
iv Yoshio H. et al. First line of defense in early life. Semin Perinatil. 2004 Agu;28(4):304-11.
v Tollin M, et al. Antimicrobial peptides in the first line defence of human colon mucosa. Peptides. 2003 Apr;24(4):523-30.
vi Antibiotic Resistance: World Health Organization Fact Sheet.
vii Meddles-Torres, C, et al. Changes in prescriptive practices in skin and soft tissue infections associated with the increased occurrence of community acquired methicillin resistant Staphylococcus aureus. Journal of Infection and Public Health. 2013 Apr 30;6:423-430.
viii Bragg RR, et al. Potential Treatment Options in a Post-antibiotic Era. Adv Exp Med boil. 2018;1052:51-61.
ix Review on Antimicrobial Resistance. Antimicrobial Resistance: Tackling a Crisis for the Health and Wealth of Nations. 2014. Chaired by Jim O’Neill.
x Matejuk A, et al. Peptide-based Antifungal Therapies against Emerging Infectins. Drug Future. 2010 Mar;35(3):19.
xi Carriel-Gomes MC, et al. In vitro antiviral activity of antimicrobial peptides against herpes simplex virus 1, adenovirus, and rotavirus.Mem Inst Oswaldo Cruz. 2007 Jun;102(4):469-72.