(Listeriosis)

Listeriosis is a severe but relatively uncommon infection caused by Listeria monocytogenes . Listeriosis primarily is foodborne and occurs most frequently among pregnant women and their fetuses or newborn infants, people of advanced age, or immunocompromised people. Infections are categorized as maternal, neonatal, or childhood with or without associated predisposing conditions. Maternal infections can be asymptomatic or can be associated with an influenza-like illness, fever, malaise, headache, gastrointestinal tract symptoms, and back pain. Approximately 65% of women experience a prodromal illness before the diagnosis of listeriosis in their fetus or newborn infant. Amnionitis during labor, brown staining of amniotic fluid, or asymptomatic perinatal infection can occur. Neonatal illnesses have early-onset and late-onset syndromes similar to those of group B streptococcal infections. Preterm birth, pneumonia, and septicemia are common in early-onset disease. An erythematous rash with small, pale papules characterized histologically by granulomas can occur in severe newborn infection and is termed "granulomatosis infantisepticum." Late-onset infections occur after the first week of life and usually result in meningitis. Clinical features characteristic of listeriosis outside the neonatal period or pregnancy are meningitis with or without parenchymal brain involvement in: (1) immunocompromised hosts, including people with organ transplantation, acquired immunodeficiency syndrome, hematologic malignancies, or immunosuppression attributable to corticosteroids; (2) people older than 50 years of age; or (3) people for whom reports from the laboratory indicate "diphtheroids" on Gram stain or culture. L monocytogenes also can cause rhombencephalitis (brain stem encephalitis), brain abscess, and endocarditis. Outbreaks caused by contaminated food usually are characterized clinically by fever and diarrhea.