Listeriosis

1
Listeriosis

• PREP, May 2004
• Nelson, 17th ED

2
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 doesnt cause disease.

3
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.

4
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.

5
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.

6
Epidemiology

• IP 3 weeks-30 days.
• 5 of healthy adults have Listeria species in
  their stool (usuallylt1 mo).
• Infectious dose 104- 106 / gram of ingested
  product lower in special situations.
• 0.7/100,000 general 10/100,000 infants
  1.4/100,000 elderly.
• Males more.

7
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.

8
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.

9
Immunity

• T cell mediated.
• It is prevented through routine prophylaxis for
  Pneumocystis carinii in HIV patients.
• Complement, opsonizing antibodies ?

10
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.

11
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.

12
Neonatal DiseaseEarly Onset

• 1.5 days (lt5 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).

13
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.

14
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.

15
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.

16
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.

17
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.

18
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.

19
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.

20
Prevention

• Zero tolerance policy.
• Prophylaxis.
• Vaccine.
• It is a reportable disease.

21
THANK YOU