Listeriosis
Listeriosis is infection with the gram-positive bacillus Listeria monocytogenes that can cause many problems, including meningitis, eye infections, miscarriage, vomiting, and diarrhea.
Listeria monocytogenes occurs worldwide in the environment and in the intestines of many animals. Most cases of listeriosis occur in July and August and result from consumption of contaminated food--typically meat, dairy products, and raw vegetables. Surveys of common fresh foods have found the bacteria in 15 to 70% of samples. Despite the high prevalence of the bacteria, listeriosis is rare, with about 1,000 cases each year in the United States. Newborns, people older than 70, and those with a weakened immune system are most susceptible.
Symptoms and Diagnosis
Listeriosis can affect almost any organ in the body, but in adults and newborns the most common site of infection is the meninges (the tissues covering the brain and spinal cord), causing meningitis. Meningitis produces fever and a stiff neck; without treatment, confusion, coma, and death can result. Brain abscesses (collections of pus) may form in up to 20% of people with meningitis.
The bacteria may sometimes infect the eyes, making them red and painful. The infection can spread to the lymph nodes, blood, and meninges. In rare instances, infection of the heart valves (endocarditis) can produce heart failure and lead to death.
While listeriosis during pregnancy may not be recognized in the mother, the fetus may die in the womb, leading to miscarriage, or the infant may die shortly after delivery. Sometimes well-appearing infants that are born to infected mothers develop meningitis a week or two after birth.
Diagnosis usually requires culture of a sample of tissue or body fluid. Antibodies against the bacteria can also be detected in blood samples.
Treatment
Treatment with the antibiotic ampicillin generally cures listeriosis. If the heart valves are infected, a second antibiotic (such as tobramycin) may be given at the same time. Eye infections can be treated with oral erythromycin.
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