listeria infection
TRANSCRIPT
Listeria infection
Etiology
• Species L. monocytogenes• Gr+• Aerobic• Motile with its 1-5 flagella • Non-spore forming• Rodlike
Transmission • L. monocytogenes infects many domestic and wild animals • Transmitted to humans by eating infected animals or animal
products
Pathogenesis
• Enters the human body by ingesting the contaminated food• Has virulence factor listeriolysin O that allows it to escape the
phagolysosomes of macrophages and avoid intracellular killing
Symptoms of Listeriosis • Mild symptoms: • Fever• Muscle aches • Nausea • Diarrhea
• Severe symptoms:• Meningitis • Mental changes• Brain abscess • Death
People at risk of infection • Pregnant women• Fetus and neonate• Elderly and immunocompromised
Infection in pregnant woman
• Usually occurs in third semester when the cell-mediated immunity decreases
• The bacteria infects the fetus and 22% of these infections result in neonatal death
• Surviving babies are often born prematurely with active infection
• Prophylaxis: pregnant women should avoid milk, soft cheeses, butter and deli meals
Infection in fetus and neonate
• Infection is acquired in utero • Can also be contracted from an asymptomatic mother, with
vaginal colonization with Listeria during vaginal birth• This type of infection results in neonatal meningitis presenting
about 2 weeks post-partum• Listeria monocytogenes causes 20% of all neonatal meningitis
Infection in elderly and immunocompromised
• Is the second most common cause of meningitis, after Pneumococcus, in people over 50 years old
• Immunocompromised patients at risk are:• Patients with lymphoma • Patients receiving organ transplantation• Patients on corticosteroids• Patients with AIDS
Infection in immune component hosts
• Listeria monocytogenes is a facultative intracellular organism• In immune component host it is not likely to cause infection
due to cell-mediated immunity
Diagnosis • Confirmed by lumbar puncture• Cerebrospinal fluid analysis reveals a high number of
neutrophils, increased protein level, decreased glucose level • Positive gram stain showing gram-positive rods
Treatment • Fluid 0,9% NaCl• By antibiotics:• Ampicillin
• Children: 75 mg/kg/day• Adults: 150 mg/kg/day
• Trimethoprimsulfamethoxazole • Children: 2x100mg/day• Adults: 2x400mg/day
Prevention • Cook food properly at high temperature• Treating/pasteurizing fluids • Avoid food or fluids that might have been in contact with
animals or human waste
Sources • http://www.medicinenet.com/listeria/article.htm• Lange: medical microbiology• Andreas Russ: Arzneimittel pocket