Lecture 10. Infections of the Nervous System 1

what is the most common cause of listeria

listeria monocytogenes

etiology of listeria monocytogenes

gram-positive, facultative anaerobic, non spore forming rod bacteria that is temperature and pH tolerant and hydrolases esculin

the hemolytic colonies formed on blood agar of listeria monocytogenes appear what color when illuminated

blue-green

when enzyme tested, listeria monocytogenes is positive for....

1. catalase

2. CAMP (w/ S. aureus)

listeria monocytogenes

what bacteria is this

listeria ivanovii is commonly associated with what c/s

abortions in sheep and cattle

listeria monocytogenes can sometimes be known to cause what in addition to neural form in sheep, cattle, and goats

ocular form

what are the different forms of listeria

1. neural: meningoencephalitis leading to circling

2. visceral: neonate septicemia

3. abortions: sporadic abortions

what cranial nerves are affects by the neural form of listeria monocytogenes

V, VII, VIII

the neural form of listeria monocytogenes is sometimes also referred to as

silage disease

isteria monocytogenes

c/s of listeria monocytogenes neural form

1. ADR and neurological signs

2. microabscesses on perivascular and lymphocytic cuffing in brain stem

where do microabscesses occur in the visceral form of listeria

heart, liver, kidneys

how is listeria monocytogenes transmitted

1. fecal oral (environment and other animals GIT)

2. fecal oral (poor silage)

3. transplacental sometimes

how do listeria monocytogenes avoid being phagocytized (virulence factor)

listeriolysin (hemolysin)

what do listeria monocytogenes do after they avoid being phagocytized in order to infect surrounding cells (virulence factor)

polymerize actin into tails

how does listeria monocytogenes actually cause disease

penetrate M cells in Peyer's patches and spread via lymph and blood

what additional ways can CNS listeria monocytogenes occur

1. bacteriemia

2. invasion through dental pulp followed by trigeminal nerve infection

how do we Dx. listeria monocytogenes

1. C/s

2. Specimens specific to form of disease (CSF, uterine discharge, liver etc..)

3. histo of brain to see microabscesses

microabscesses of listeria monocytogenes

what does this histology slide reveal

what is the drug of choice for listeria monocytogenes

high doses of penicillin

what form of feed can discourage listeria monocytogenes growth

immature corn + grass w/ additives (more acidic pH)