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. Inmany cases people get these infections in the hospital. Klebsiella andProteus 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 digestivetract usually start when the organisms invade its lining. These bacteria maybe present in the stomach and intestines, transmitted by contaminated food and water, or spread by person-to-person contact. The usual incubation period is 12-72 hours. Escherichia coli infections cause most of the enterobacterialinfections in the United States. Noninvasive types of E. coli includeenteropathogenic E. coli, or EPEC, and enterotoxigenic E. coli,or ETEC. EPEC and ETEC types produce a bacterial poison (toxin) in the stomach that interacts with the digestive juices and causes the patient to lose large amounts of water through the intestines. Invasive types of E. coliare called enterohemorrhagic E. coli, or EHEC, and enteroinvasive E. coli, or EIEC. These subtypes invade the stomach tissues directly, causing tissue destruction and bloody stools. EHEC can produce complications leading to hemolytic-uremic syndrome (HUS), a potentially fatal disorder markedby the destruction of red blood cells and kidney failure. EHEC has become a growing problem in the United States because of outbreaks caused by contaminated food. One type of EHEC known as O157:H7 has been identified in undercooked hamburgers, unpasteurized milk, and apple juice. The symptoms of enterobacterial infections are sometimes classified according to the type of diarrhea they produce: Bloody diarrhea (sometimes called dysentery) usually requires antibiotics while watery diarrhea does not. Necrotizing enterocolitis (NEC) is a disorder in newborns, primarily premature newborns.
The diagnosis of enterobacterial infections is complicated because viruses, protozoa, and other types of bacteria can also cause diarrhea. In most cases of mild diarrhea, it is not critical to identify the organism because the disorder is self-limiting. Patients who should have stool tests include those with: bloody diarrhea, watery diarrhea who have become dehydrated, watery diarrhea that has lasted longer than three days, and disorders of the immune system. The patient history helps the doctor determine what type of enterobacteriummay be causing the infection. The most important parts of the physical examination are checking for signs of severe fluid loss and examining the abdomento rule out typhoid fever. The doctor will look for signs of dehydration. Themost common test to identify the cause of diarrhea is examining a stool sample under a microscope. Routine stool cultures, however, will not identify anyof the types of E. coli that cause intestinal infections. ETEC, EPEC,and EIEC can usually be identified only by research laboratories. Because ofconcern about EHEC outbreaks, however, most laboratories in the United States can now screen for O157:H7 with a test that identifies its toxin. All patients with bloody diarrhea should have a stool sample tested for E. coliO157:H7.
Enterobacterial diarrhea is usually treated by fluids to restore the electrolyte balance and paregoric to relieve abdominal cramping. Newborn infants andpatients with immune system disorders will be given antibiotics intravenously once the organism has been identified. Gentamicin, tobramycin, and amikacin are frequently used to treat enterobacterial infections because many of the organisms are becoming resistant to ampicillin and cephalosporin. Alternative treatments can relieve the discomfort of abdominal cramping, but mostalternative practitioners advise consulting a medical doctor if the patient has sunken eyes, dry eyes or mouth, or other signs of dehydration. Herbalistsmay recommend cloves, ginger, peppermint (Mentha iperita), or chamomile (Matricaria recutita) tea. Homeopathic practitioners frequently recommend Arsenicum album, Belladonna, Veratrum album, and Podophyllum. The prognosis for most enterobacterial infections is good;most patients recover in about a week or 10 days without antibiotics. HUS has a death rate of 3-5%. About a third of the survivors have long-term kidneyproblems, and another 8% develop high blood pressure, seizure disorders, andblindness. The World Health Organization (WHO) offers these suggestions for preventing enterobacterial infections: Cook ground beef or hamburgers until the meat is thoroughly done; do not drink unpasteurized milk or use products made from raw milk; wash hands thoroughly and frequently, especially after using the toilet; wash fruits and vegetables carefully, or peel them; keepall kitchen surfaces and serving utensils clean; if drinking water is not known to be safe, boil it or drink bottled water; and keep cooked foods separate from raw foods, and avoid touching cooked foods with utensils that have been used with raw meat.