Salmonella Infections
Infection with any of several species of the gram-negative bacilli Salmonella results in gastroenteritis and sometimes local tissue infections.
About 2,200 types of Salmonella are known, including the one that causes typhoid fever (see Section 17, Chapter 190). Each type can produce gastrointestinal upset, enteric fever, and specific localized infections. With the exception of the type that causes typhoid fever, Salmonella infects the digestive tracts of many domestic and wild animals, birds, and reptiles. Contaminated foods--particularly meat, poultry, eggs, egg products, and raw milk--are common sources of Salmonella. Another source is infected pet reptiles (snakes, lizards, turtles). Up to 90% of pet reptiles in the United States are infected with Salmonella. Salmonella infections are a significant public health problem in the United States.
Symptoms and Diagnosis
Symptoms of Salmonella infection are usually confined to the digestive tract and start 12 to 48 hours after ingesting Salmonella. The first symptoms are nausea and cramping abdominal pain, soon followed by watery diarrhea, fever, and sometimes vomiting. The infection is often gone within 1 to 4 days, but it may last much longer. Some people become carriers and continue to pass the bacteria in their stool well after symptoms are gone.
Very rarely, Salmonella leaves the intestines and travels through the bloodstream to infect other sites, such as the bones (particularly in people with sickle cell disease), joints, or heart valves. Occasionally, a tumor may become infected and develop an abscess that provides a source for continued blood infection.
Diagnosis is confirmed in a laboratory by culturing a rectal swab or sample of stool or blood taken from an infected person.
Treatment
Salmonella gastroenteritis is treated with fluids and a bland diet. Antibiotics do not shorten recovery time but do prolong the excretion of bacteria in the stool and are therefore usually not given. However, infants, people in nursing homes, and those with a weakened immune system are given antibiotics because they are at higher risk for complications. In carriers who do not have symptoms, the infection usually resolves on its own; antibiotic treatment is rarely needed and may not be effective.
People with Salmonella in their blood must take antibiotics for 4 to 6 weeks. Abscesses (collections of pus) are treated by surgical drainage and 4 weeks of antibiotic therapy. People with infection in blood vessels, heart valves, or other sites generally require surgery and prolonged antibiotic therapy.
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