Klebsiella pneumoniae is an opportunistic pathogen associated with pneumonia, bloodstream infections, and other antibiotic-resistant diseases. Although the bacterium can colonize the gastrointestinal tract, its interactions with the intestinal mucus layer have remained poorly understood.

A new study published in Microbiome Research Reports found that multiple K. pneumoniae strains strongly adhered to both human and porcine intestinal mucus in vitro and localized within the mucus layer in mice. These findings suggest that mucus may provide an important niche for gut colonization.

The researchers also showed that K. pneumoniae could use several mucus-associated sugars, including galactose, fucose, and N-acetyl-glucosamine, to support growth. However, the bacterium could not efficiently grow on intact mucus alone because it lacks key enzymes needed to fully degrade complex mucin glycans. According to the authors, this suggests that K. pneumoniae may rely on other gut microbes to release these nutrients during microbiome disruption.

In addition, the study found that mucus exposure increased K. pneumoniae sensitivity to the aminoglycoside antibiotics gentamicin, kanamycin, and streptomycin. The authors propose that mucus may alter bacterial physiology in ways that improve antibiotic uptake or reduce resistance mechanisms.

Together, the findings identify intestinal mucus as more than a physical barrier, showing that it can shape K. pneumoniae colonization, nutrient utilization, and antibiotic responsiveness. The researchers suggest these interactions may be important for understanding how opportunistic pathogens expand in the gut and how antibiotic therapies could potentially be improved.

The work titled “Intestinal mucus acts as a nutrient source and signal for Klebsiella pneumoniae”, was published on Microbiome Research Reports (published on April 29th, 2026).
DOI：10.20517/mrr.2025.112