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Listeriosis. PREP, May 2004 Nelson, 17 th ED. Historical perspective. L. monocytogenous, why? Previously a rare cause of infection but today is isolated more frequently, why? Refrigerators. Highly processed food. Extended shelf life of foodstuffs.

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listeriosis

Listeriosis

PREP, May 2004

Nelson, 17th ED

historical perspective
Historical perspective
  • L. monocytogenous, why?
  • Previously a rare cause of infection but today is isolated more frequently, why?
  • Refrigerators.
  • Highly processed food.
  • Extended shelf life of foodstuffs.

However it usually doesn’t cause disease.

microbiology
Microbiology
  • Facultatively anaerobic G , non spore forming motile bacillus/ coccobacillus/ diplococci,or diphtheroids like.
  • It can tolerate low temperatures (4), high pH, high salt conc. So can replicate in soil, water, sewage, … & contaminated refrigerated foods.
  • Destroyed by pasteurization & most disinfecting agents.
microbiology4
Microbiology
  • L. monocytogenous is the commonest of the 7 species of the genus Listeria in causing disease.
  • On a semisolid media, demonstration of a tumbling motility, umbrella-type formation, hemolysis, & typical cAMP test are sufficient to establish a presumptive diagnosis of L mono.
epidemiology
Epidemiology
  • Important cause of zoonoses.
  • F- O transmission in animals.
  • Usually food- borne.
  • Animal to human by direct contact.
  • Vertical or horizontal transmission.
  • Cross- infection in a neonatal unit through contact with a contaminated mineral oil used to bathe infants.
epidemiology6
Epidemiology
  • IP 3 weeks-30 days.
  • 5% of healthy adults have Listeria species in their stool (usually<1 mo).
  • Infectious dose 10*4- 10*6 / gram of ingested product & lower in special situations.
  • 0.7/100,000 general; 10/100,000 infants; 1.4/100,000 elderly.
  • Males more.
pathogenesis
Pathogenesis
  • It causes granulomatous reactions & micro abscesses.
  • Translocations in animals.
  • It can cross the intestinal mucosal barrier & once in the blood stream, the bacteria may disseminate hematogenously to any site but mostly to the CNS or placenta, liver, & spleen.
pathogenesis8
Pathogenesis
  • It has the ability to escape from antibodies, complement, & neutrophils.
  • Intercurrent GI infection with another pathogen, as shigella sp., may enhance invasion in individuals infected with L monocytogenous. & it may enhance the transfer of intraluminal m.o across the intact intestinal mucosa.
immunity
Immunity
  • T cell mediated.
  • It is prevented through routine prophylaxis for Pneumocystis carinii in HIV patients.
  • Complement, opsonizing antibodies ?
clinical aspects
Clinical Aspects
  • The enteric phase is usually asymptomatic, then the bacteria crosses the intestinal barrier to be transmitted inside the macrophages to any organ but mostly to the spleen & liver.
  • Disease & its severity depends on several factors.
intrapartum disease
Intrapartum Disease
  • Listeriosis in pregnancy: documented mostly in the 3rd trimester.

Early: abortion.

Second & third trimester: flu like

illness or GI, rarely meningitis with/without

fetal involvement ; stillbirth,

premature labour (mortality rate 50-

90%). It may resolve after delivery even

without treatment.

neonatal disease early onset
Neonatal DiseaseEarly Onset
  • 1.5 days (<5 days), mostly through the placenta (can be ascending).
  • Strong association with maternal disease.
  • Septic like picture predominates, but can be ARD, Pneumonia, Meningitis, Myocarditis.
  • Granulomatosis infantisepticum which are widely disseminated granulomas present in severe listerial disease (skin, liver, placenta).
late onset
Late Onset
  • Symptoms are several days to weeks after birth, usually at 14.3 days (5-30) of age.
  • Transmission is vertical or nosocomial.
  • Mostly as meningitis, in a term infant.
  • Less common.
  • Mothers are culture negative.
nonperinatal disease
Nonperinatal Disease
  • Most common M.O as a cause of meningitis in patients with lymphoma, organ transplant recipients, in those receiving corticosteroids, & in the elderly.
  • Risk factors include DM., Liver disease, chronic renal disease, collagen vascular disease, iron overload, & diminished gastric acidity. However 54% of children have no apparent immunocompromising condition.
nonperinatal disease15
Nonperinatal Disease
  • After the neonatal period 30-55% present with meningitis. 30% will have neurologic sequelae (MR, hydrocephalus, e.t.c.)
  • Rhombencephalitis in healthy adults diagnosed by MRI.
  • Bacteremia in immunocompromised.
  • Infection in other body organs.
diagnosis
Diagnosis
  • It should be included in the differential diagnosis of infection in pregnancy, neonatal sepsis, meningitis.
  • CBC.
  • Gram stain.
  • Culture / 36 hr incubation/ blood, CSF, cervix, vagina, placenta.

Alert the lab not to discard as a contaminating diphtheroids.

diagnosis17
Diagnosis
  • CSF. Glucose, Blood Culture, Gram Stain, Protein.
  • Rapid detection by MA/ NAH.
  • PCR: not available commercially.
  • Anti-listeriolysin O, a hemolysin mediates lysis of vacuoles & is responsible for the zone of hemolysis when grown on blood containing solid media.
  • Serological test: not available.
  • Detect contact with animals.
management
Management
  • No available controlled trials about the exact drug or duration of treatment but a minimum of 2 weeks is needed.
  • Many factors make treatment difficult.
  • Antibiotics.
prevention
Prevention
  • Food-borne listeriosis: keeping uncooked meat separate from vegetables. Washing hands, knifes, & cutting boards after exposure to uncooked food. Regular cleaning & disinfection of the insides of refrigerators. At risk patients should avoid soft cheeses, reheat ( until steaming hot) leftover & ready to eat foods, avoid cold cuts if unable to reheat thoroughly.
prevention20
Prevention
  • Zero tolerance policy.
  • Prophylaxis.
  • Vaccine.
  • It is a reportable disease.