Another organism that has more recently become problematic is Clostridium difficile. Usually, normal gut flora resist overgrowth and colonization by this organism. However, antibiotic use that suppresses the normal gut flora, allows proliferation of C. difficile. The organism releases toxins that cause inflammation and damage to the mucosal lining of the colon, leading to severe diarrhea.
An antibiotic-resistant strain has developed that can result in colitis, sepsis, and death. Elderly patients, patients with severe underlying illness, and patients undergoing immunosuppressive therapy are at higher risk of becoming infected since their immune response to the bacteria and its toxins is diminished.