C. diff (Clostridium difficile) is a Gram-positive bacterium that forms spores. It is an anaerobic (does not require oxygen) bacteria that is motile and commonly found anywhere, particularly in soil. The cells that are vegetative are rod-shaped, have the ability to alter their shape to adapt to the environment (pleomorphic), and usually occur in short chains or pairs. When viewed under a microscope, this organism appears to have a drumstick shape cell where there is a bulge at the ends (to form spores).
C. diff shows optimal growth in blood agar in the absence of oxygen at human body temperatures. It produces cytotoxin B and enterotoxin A, resulting in disruption of signal transduction in the host. When in hostile conditions, C. diff produces spores that are able to tolerate conditions that the active bacteria are not able to. It can become established in the colon and can be found in 2% to 5% of the adult population.
C. diff can produce enterotoxin A and cytotoxin B, which can cause inflammation and diarrhea in individuals who are affected. The diarrhea in patients can be loss of fluid from the intestines or it can also become life-threatening pseudomembranous colitis where there are formation of pseudomembranes and intense inflammation of the colon. There is also an adhesin factor that increases the binding to the colonic cells. Paracresol produced by the bacterium also inhibits other microbial growth to prevent competition for resources. Treatment of C. diff can be difficult due to the physiological abilities of the bacterium (such as protection from pseudomembrane and formation of spores) and increasing antibiotic resistance.