Listeria

Question 1

Incidence of Listeriosis

Answer 1

Uncommon in Australia and NZ
0.3-0.56 per 100,000
18x more common in pregnancy

Question 2

Advice to prevent transmission of Listeria

Answer 2

1. Avoid High Risk Foods
   - unpasteurised milk / raw milk foods
   - pates, dips, soft cheeses
   - chilled pre-cooked seafoods
   - precooked meats / meats without further cooking / cold meats
   - uncooked / smoked seafood
   - pre-packed fruit salads and coleslaws
   - rockmelon
   - soft serve ice-cream
   - sprouted seeds and raw mushrooms
2. Safe Food Handling
   - wash hands
   - wash raw fruit and vegetables
   - thoroughly cook raw meat / seafood
   - freshly cooked foods
   - avoid dips (where raw vegetables previously dipped)
   - reheat food until steaming hot
   - separate cutting boards

Question 3

When is transmission of listeria in pregnancy highest and what is the fetal mortality rate?

Answer 3

Highest in third trimester.
Fetal mortality 25-50% in second/third trimesters.

Question 4

Rate of faecal carriage of listeria monocytogenes?

Answer 4

0.6-16% of population
Invasive disease is rare

Question 5

Incubation period for invasive listeria

Answer 5

0-70 days (median. 10)
Longer for pregnancy associated (≤6 weeks for 90%)

Question 6

L Monocytogenes

Answer 6

Gram positive rod
Facultative intracellular
Facultative anaerobic (survives in both)
Produces beta haemolysins
Flagella and motile <37 deg
Can survive in food even in the fridge

Question 7

Maternal illness (listeriosis)

Answer 7

Unwell, febrile, flu-like illness in third trimester
30% asymptomatic
30% flu-like illness
80% fever

Question 8

Perinatal transmission risk (listeria)

Answer 8

1. Most transmissions in third trimester
2. High rate of transmission (96% in Monalisa study)
3. > 29 wks or maternal hospital admission >2 days associated with fetal survival

Question 9

Rate of fetal or neonatal complications with listeria transmission

Answer 9

83%
- Fetal loss/miscarriage/stillbirth (13-24%)
- Overall perinatal mortailibty ~50%
- >29 weeks or maternal hospital admission >2 days associated with fetal survival

Question 10

Lab investigations for listeriosis

Answer 10

1. Culture from sterile site (blood culture 55% positive, CSF, placenta
2. Genital tract swab (may have asymptomatic carriage)

Question 11

Treatment for listeriosis

Answer 11

IV amoxicillin / ampicillin
≥14 days (blood stream)
≥21 days (meningitis)
Trimethoprim/sulfamethoxazole if pen allergy
Urgent delivery depending on severity of maternal illness and gestation

Question 12

Antenatal steroids in listeriosis

Answer 12

Not recommended if CNS listeria as survival lower (in MONALISA stuy)

Question 13

Mortality rates for infected neonates (listeriosis) born alive

Answer 13

20-60%

Question 14

Neonatal investigations (listeriosis)

Answer 14

1. Placenta MCS + histopath
2. Superficial swabs, blood culture, CSF
3. CXR
   4 FBC

Question 15

Clinical Findings in unwell Neonate (listeriosis)

Answer 15

1. Granulomatosis infantiseptica
2. Meconium stained liquor <34 weeks
3. Pneumonitis
4. Purulent conjunctivitis
5. Late onset disease can occur in term infants, 4-6 weeks post-partum (often meningitis, mortality 10-20%)