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Micro - Listeria (esp L Monocytogenes) (intro (opportunistic (pregnant…
Micro - Listeria (esp L Monocytogenes)
intro
gram +ve bacillis
non-sporing
aerobic/facultative anaerobic
tumbling motility @ 25 degrees
ubiquitous (water, soil, animal faeces, plants)
grows in wide temp range (2-37) - can grow in refrigerated food!
increased incidence in warm months (more salad eaten)
most infections in healthy adults are asymptomatic/mild ILI/diarrhoea
opportunistic
pregnant women (esp 3rd trimester - less cell/mediated immunity)
also neonates. lymphoma, transplant recipients, DM, high dose steroids, haemosiderosis, HIV, splenectomy
causes community-acquired neonatal/congenital meningitis, meningoencephalitis (meninges + brain) + rhombencephalitis (inflamm of hindbrain - medulla, pons, cerebellum)
transmission
animal contact
ingesting contaminated milk, soft cheese, paté, veg
vertical
mother -> child
vagina infected via GIT
Pathogenesis
ingestion - can cross mucosal barrier - dissemination
can survive + multiply in macrophages
human infection uncommon
can move from cell to cell without exposing itself to extracellular environment
T cells needed for intracellular killing
Perinatal listeriosis
esp in 3rd trimester
ILI
fever
myalgia
backache
headache
arthralgia
complications
IU death
premature labour
miscarriage
newborn infection (neonatal listeriosis)
Neonatal listeriosis
early onset
in 1st 2 days of life
IU acquistion - ascending infection
40-50% mortality
septicaemia, granulomatous pneumonia, CR distress, hepatosplenomegaly, abscesses, CNS involvement
late onset
2-5 days old
acquired from birth canal
more common
12% mortality
meningitis, meningoencephalitis, rarely septicaemia
Symptoms
in immunocompromised
pneumonia
brain abscess
endocarditis
PUO
septicaemia
meningoencephalitis
in healthy adults
ILI
gastroenteritis-like illness
diarrhoea, headaches, fever, chills
Dx
mother
blood culture, urine/stool, vaginal/placental swab
neonate
blood, CSF, meconium
adult
blood, CSF
Tx
combination Tx for synergy
high dose ampicillin + aminoglycoside (gentamycin)
inherently cephalosporin-resistant
Prevention
high risk people shouldn't eat raw/partially cooked animal produce, paté, soft cheese, unwashed veg
immigrant pop @ risk - communication around safe eating NB