What Member of the Human Intestinal Microbiota Occasionally Causes Life-Threatening

Question

What member of the human intestinal microbiota occasionally causes life-threatening disease?
A) Escherichia coli O157:H7
B) Clostridium difficile
C) Salmonella enterica
D) Giardia intestinalis
E) Lactobacillus

Accepted Answer

Clostridium difficile can sometimes overgrow and produce toxins that cause severe diarrhea, colon inflammation, and even life-threatening colitis. This bacterium is a member of the human intestinal microbiota, but it can cause harm under certain circumstances, such as prolonged antibiotic treatment or suppressed immune system. Escherichia coli O157:H7 and Salmonella enterica are also pathogenic bacteria that can cause serious foodborne infections, but they are not part of the normal gut microbiota. Giardia intestinalis is a protozoan parasite that can cause gastrointestinal illness, but it is not a bacterial member of the gut microbiota. Lactobacillus is a beneficial bacterium that can promote digestive health and prevent infections, but it is not known to cause any diseases in healthy individuals.