Repurposing bacteria to fight disease

Antibiotic treatment of bacterial diseases is complicated by issues such as side effects from systemic drug administration, the widespread increase in antibiotic resistance, and the lack of new narrow-spectrum antibiotics being developed. Additionally, antibiotic therapy can inadvertently eliminate beneficial bacteria within the gut, detrimentally changing the gastrointestinal microbiome. This situation commonly occurs in individuals treated broad-spectrum antibiotics who then develop Clostridioides difficile infection. Subsequent C difficile-targeted antibiotics bring initial relief by killing this pathogen (which causes symptoms such as colitis and diarrhoea), but they also eliminate beneficial Firmicutes within the natural intestinal microbiome, thus enabling lingering C difficile spores to germinate and renew infection of the host after antibiotic discontinuation.