Listeria Monocytogenes Flashcards
what shape does listeria monocytogenes have?
rods
what Foods are associated with this bacteria *?
- Soft cheeses
- Deli meats
- Cabbages (coleslaw)
- Unpasteurized milk products
who is at high risk for severe infection with listeria?
weakened or immature immune system: *
- Developing fetus, newborn infants (via infected mother) *
- Older adults (65 yrs or older) *
- Individuals with defective cell-mediated immunity*
listeria monocytogenes is considered what type of organism?
Facultative Intracellular parasite *
is listeria motile?
yes
what type of motility does listeria have?
tumbling motility
in what temp. does listeria grow?
cold temp.
what is an example of a food where listeria grows?
hot dogs *
how does listeria transmit?
foodborne and from mother to fetus *
where will listeria attach to when ingeted?
to macrophages and intestinal epithelium
what will allow listeria to allows escape from phagosome of macrophages?
Listeriolysin-O*(hemolysin)
what will allow Listeria to spread from cytoplasm of one host cell to another host cell?
actin-jet filament → jet motility *
what tissues does listeria prefer?
placenta and central nervous system
how well do antibodies act towards listeria?
Antibodies to Listeria are ineffective due to being intracellular
what immunity is needed to attack listeria infection?
cell-mediated immunity
what can an infection with listeria cause in Pregnant women *?
miscarriage*
what can an infection with listeria cause in newborns* if infection occurs in early onset?
granulomatosis infantiseptica
what can an infection with listeria cause in newborns* if infection occurs in late onset?
Septicemia and meningitis
what can an infection with listeria cause in immunocompromised individuals and older adults?
Septicemia and meningitis
what is Granulomatosis infantiseptica* found in neonatal listeriosis?
disease acquired transplacentally that causes disseminated abscesses and granulomas *
How is Meningitis* acquired in neonatal listeriosis? What is it accompanied with usually?
- Transmission during delivery
- Usually accompanied by septicemia
how is listeria monocytogenes diagnosed?
1) Gram stain of CSF * and will find:
- Intracellular & extracellular short GPRs (coccobacilli)
- “Tumbling motility”**
2) Cold enrichment *
* put specimen in nutrient broth in refrigerator
what is the treatment for Treatment of Listeriosis?
- Penicillin / ampicillin + gentamycin * *
why can’t cephalosporins be used for listeria monocytogenes?
Cannot use cephalosporins (Listeria are naturally resistant)***
if a mother has antibodies against listeria and is pregnant, is her fetus at risk?
yes, and may lead to spontaneous abortion
