Ng KM, Ferreyra JA, Higginbottom SK et al. Microbiota-liberated host sugars facilitate post-antibiotic expansion of enteric pathogens. Nature 502(7469), 96-99 (2013). The human gut microbiota is a complex system of commensal microorganisms required for normal host physiology. Disruption of this protective barrier by antibiotics creates opportunities for enteric pathogens to establish infections. Although the correlation between the use of antibiotics and enteric infections have been known for some time, the specific signals that allow enteric pathogens to recognize a susceptible host have not been determined. In a recent article, Ng et al. demonstrated that the expansion of both Salmonella typhimurium and Clostridium difficile infections is enhanced by the availability of host-specific sugars liberated from the intestinal mucus by commensal bacteria. These results show how antibiotic removal of specific species from the gut microbiome allows symbiotic functions to be hijacked by pathogenic species.