Experts have reflected on the lessons that poo can teach about antibiotics.

Antibiotics have been vital in killing a range of bacteria that cause infections, but they also deplete our gut microbes, impairing our immune system, and increasing vulnerability to infection.

But the lessons learned from how antibiotics impact the body are helping researchers find new approaches to prevent and/or correct the adverse side effects on our ‘good’ gut bacteria.

The first lesson is that antibiotics disrupt communication between gut microbes and the immune system, creating conditions that favour infection.

“Treatment with antibiotics, by reducing the amount of competing commensals, increases available sugars and, in some settings, favors pathogen expansion,” says US-based researcher Eric Pamer.

Experts have also learned that antibiotic use becomes a selective pressure on bacteria, driving antibiotic resistance.

Recent research has shown that the pool of antibiotic resistance genes within an individual's microbiome “expands over time” as the person ages and is exposed to more antibiotics.

One study has demonstrated that 40 per cent of bacteria from human and animal hosts carried resistance genes to one of the categories of broad-spectrum antibiotics (quinolones), “even in subjects that had never been exposed clinically,” notes first author Simone Becattini.

Finally, experts say they have learned that antibiotics are not the only solution, and strategies to specifically target infectious bacteria are in early development.

Future approaches to treating bacterial infections will either complement current antibiotics or provide a more narrowly targeted alternative.

One complementary treatment boosts the production of antimicrobial factors by immune cells; following bacterial eradication with antibiotic treatment, the injection of immune-stimulatory molecules into the blood jolts immune cells and has been shown to successfully protect mice from potential bacterial colonization in the intestine.

Other promising alternatives to broad-spectrum antibiotics include:

  • Bacteriocins, which are proteins produced by bacteria to kill competitors. “The use of bacteriocins or bacterial strains that are engineered to carry bacteriocins would selectively kill the pathogens without altering the microbiota,” says Becattini
  • CRISPR-CAS9 gene editing can be used to cut out antibiotic resistant genes from infectious bacteria. This approach has already been shown to efficiently target specific bacteria where signs of resistance fail to develop afterwards
  • Fecal material transplants can also help restore commensal gut communities, mucus production, antimicrobial peptide secretion, and provide colonization resistance against pathogens that are cleared or can no longer expand

Their new paper is accessible here.