Enterobacterial infections are disorders of the digestive tract and other organ systems produced by a group of bacteria called Enterobacteriaceae. They can be produced by bacteria that normally live in the human digestive tract without causing serious disease, or by bacteria that enter from the outside. In many cases people get these infections in the hospital. Klebsiella and Proteus sometimes cause pneumonia, ear and sinus infections, and urinary tract infections. Enterobacter and Serratia often cause bacterial infection of the blood (bacteremia), particularly in patients with weakened immune systems. Diarrhea caused by enterobacteria is common in the United States and can range from a minor nuisance to a life-threatening disorder, especially in infants, elderly persons, AIDS patients, and malnourished people. Enterobacterial infections are one of the two leading killers of children in developing countries. Enterobacterial infections of the digestive tract usually start when the organisms invade its...