Zinc worsens C. difficile infections

The most common hospital-acquired infection comes courtesy of Clostridium difficile, a deadly pathogen that often preys on patients whose gut microbiome has been disrupted by antibiotics. If the findings of a new study in mice hold true for humans, excess dietary zinc can be blamed for making patients more susceptible to C. difficile infections and for increasing the severity of infection (Nat. Med. 2016, DOI: 10.1038/nm.4174). Researchers led by Eric P. Skaar of Vanderbilt University Medical Center found that excess dietary zinc reduced “the minimum amount of antibiotics needed to confer susceptibility to C. difficile infections.” Excess zinc also increases the pathogen’s toxicity. Plus, the mouse immune system deploys calprotectin, a small protein that sequesters zinc, to combat C. difficile. “Alteration in diet and limitation of excess Zn intake may prove efficacious for the prevention of C. difficile infections in high-risk patients and help limit morbidity during C. difficile infections,” the authors note. In another report, researchers led by Min Dong at Harvard Medical School have discovered a family of protein receptors that are used by C. difficile to infect host cells in the colon, a finding that could lead to new drugs to fight the pathogen (Nature 2016, DOI: 10.1038/nature19799).