Clostridium difficile also known as C. difficile, C. diff is a species of Gram-positive spore-forming bacterium. Clostridia (members of the genus Clostridium and of the Clostridiaceae family) are anaerobic, motile bacteria, ubiquitous in nature, and especially prevalent in soil. Its vegetative cells are rod-shaped, pleomorphic, and occur in pairs or short chains. Under the microscope, they appear as long, irregular (often drumstick- or spindle-shaped) cells with a bulge at their terminal ends. C. difficile is catalase and superoxide dismutase negative and produces two types of toxins: enterotoxin A and cytotoxin B, which disrupts cytoskeleton signal transductions in the host.

File under: bacteria not to be taken lightly.

Clostridium difficile (C. diff) is a pretty gnarly pathogen. If you’re about to reach for hand sanitizer—please don’t—at last count, there were already 16 resistant strains reported. People most at risk are those with a compromised microbiota (this happens for a variety of reasons like poor diet, a weakened immune system, or antibiotics-overuse) and are often infected during hospital stays.

Infections caused by C. diff are particularly insidious. It’s a challenge to treat, frequently returning again and again, and each time requiring a more extreme treatment than the last. Fecal transplants have shown incredible potential in treating C. diff. And yes, that’s exactly what it sounds like—transplanting donor poop into and recolonizing the gut of a dysbiotic host.