Listeriosis
Introduction.
Listeriosis is primarily a food-borne illness. Listeria are
common in soils, water and vegetation. Uncooked or inadequately cooked foods can
be responsible for outbreaks. Listeria are intracellular bacteria
(macrophages). Meningitis is a complication.
Summary
- Cause: Listeria monocytogenes
- Microscopy: Gram-positive rods
- Symptoms: Muscle aches, nausea, diarrhea and fever; may progress to
meningitis with headache, stiff neck, confusion, loss of balance
- Transmission: Food borne; soft cheese, cabbage
- Pathogenesis: Intracellular
pathogen: Listeria produce invasins that allow them to enter
host cells and macrophages, hiding from the immune system. Listeria then
lyse the phagosome and escape into the cytoplasm. Hemolysins cause
red blood cell lysis. Abscess formation, granulomas and other immune
responses cause tissue damage.
- Complications: Meningitis; disseminated disease in
immunocompromised due to importance of cell-mediated immunity to fighting
infection; serious infections in neonates: early-onset (disseminated
abscesses & granulomas) or late-onset (meningitis)
- Treatment: Penicillin or ampicillin (+/- gentamycin)