exam 2 Flashcards
1. There is a draining abscess of a cow, what are you differential diagnosis? A. mastitis due to stapylococcus aureus B. Mastitis due to Trueperella pyogenes C. mastitis due to corynebacterium pilosum D. A and B E. all of the above
answer : D
A. mastitis due to stapylococcus aureus (top dx for mastitis)
B. Mastitis due to Trueperella pyogenes (gave a picture given nasty lesions in udder and pyogenous means pus)
C. mastitis due to corynebacterium pilosum (causes UTI - not part of DDX)
- from the previous case, the cow mammary abscess picture.
you isolate 2 organisms, the first one is an obligate anaerobic gram negative bacteria consistent with Fusubacterium necrophorum. the second one is gram positive, faculative anaerobe, nonmotile, catalase negative diphteroids. (telling you its organism associated with lesions as before!) you immediately think of _______as the second agent.
a. staph aureus
b. corynebact. pseudo.
C. trueperella
D. streptococcus agalactiae
E. Listeria monocytogenes
Answer : E
a. staph aureus (is not a diphteroid, but it is catalyase positive. catalase is second test you do when there are gram positive cocci. catalayse positive are staph and negative are strep.)
b. corynebact. pseudo. (catalase positive. assocaited with mastitis? maybe. phagocytic intracellular orgainsims. most of these are catalase positive.)
C. trueperella (catalase negative)
D. streptococcus agalactiae ( not diphterpoid)
E. Listeria monocytogenes (is motile and is not dipteroid, is a rod)
key is the catalyase test because its distinguishes the two diphteroids. phagocytic intraceullular organism - most are catalayse positive bc it mandated destruction on hydrogen peroxide
Listeria is motile at what temperature?
25 celcius
T/F Listeria is a classic intracellular phagocytic organism
True
Which animal group are most frequently affected by Listeria?
a. avian
b. canines
c. ruminants
d. equine
c. ruminants
There are two important pathogens of Listeria.
L. monocytogens test postive in CAMP test with what bacteria?
L. invanovii test positive in CAMP test with what bacteria?
L. monocytogens : CAMP+ with S. aureus
L. invanovii : CAMP+ with R. equi
what type of cells does Listeria like to persist in?
hepatocytes
and epithelial cells/endotheial
but soto stressed hepatocytes
Which of the following is NOT a classical presentation of Listeria?
a. respiratory infection
b. septicemia
c. encephalitis
d. abortions
a. respiratory infection
these are classical signs of Listeria:
b. septicemia
c. encephalitis
d. abortions
T/F In studying Listeria, we have also discovered NK cells, cytotoxic T-cell activity, and activated macrophage response.
TRUE!
these are 3 of the MOST important cells in CMI.
Listeria has been a perfect model of the study of CMI
What is actA produced by Listeria?
protein that aids in intracellular movement by actin. Listeria hijacks actin inside the host cell.
remember motile at 25 celcius
T/F Listeria requires flagella once inside the cell
FALSE
because the actA protein allows Listeria to hijack actin from the host cell to use for intracellular movement
Listeria produces Internalins.
What are they?
surface proteins responsible for adhesion and entry to target cells. allows Listeria to penetrate cells.
T/F Listeria induce phagocytosis
True.
they want to be phagocytosed
What is the main virulence factor of Listeria bacteria?
LLO - Listeriolysin
it allows Listeria to break out of cells. releases the bact from phagosome into the cytosol.
activated at low pH
What is most likely the natural habitat of Listeria bacteria?
decomposing pant matter!
hence how ruminants are the most affects…from eating contaminated silage!
what is Silage disease?
ingestion of silage contaminated with Listeria, poor quality.
how ruminants get infected.
T/F up to 70% of humans are asymptomatic fecal carriers of Listeria.
True!
There are two routes of entry for Listeria.
what are they?
intestinal and CNS
What is the pathogenesis of the intestinal Listeria?
- cow eats infected silage. people drink infected milk
- attachment, entry, survival in cells
- dissemination
Which of the following is NOT route that Listeria can disseminate?
a. cell to cell
b. intestinal
c. bloodstream
d. phagocytes
b. intestinal
that is just a way it gets in!
Outline the pathogenesis of Listeria in the CNS.
- entry via a wound
- to trigeminal nerves
- CNS - meningitis
T/F Listeria is one of the top 5 causes of meningitis transferred from milk, in humans.
TRUE. ew.
T/F Listeria is not zoonotic.
FALSE
remember…in the milk…meningitis…
In a neurologic animal, where is the best place to sample to test for Listeria?
The spine!
It is in the CNS. will be cloudy fluid.
In a dead animal we would take sample of the brain, it is in the brain stem.
If you have a pt that is septic and suspect it may be infected with Listeria, where is the best place to get a sample for testing?
the Liver!
If you see a sheep circling in one direction and head pressing, you will be thinking?
um why is it doing that.
and maybe it is infected with Listeria and has encephalitis.
T/F in the encephalitis form of Listeria, on histology it will be common to see perivascular cuffing.
true!
T/F Histology will be an effective method to DX Listeria.
FALSE!
often hard to see a lot of Listeria bacteria.
should also do serology
T/F It is safe for a pregnant woman to be working around cattle that may be infected with Listeria.
Hell no.
False
What will commonly be seen in ruminants with septicemia due to Listeria infection?
Abortions
mainly in young.
bact can be in placentomes and cross to amniotic fluid
T/F Listeria can cause subclinical mastitis.
True
and then people drink their milk and get it!
so drink pasteurized milk….
T/F Purulent multifocal hepatitis is common with Listeria infections.
True!
and the liver is a good place to get tissue samples!
T/F chinchillas are quite susceptible to listerial septicemia
apparently so…TRUE
Please explain “cold enrichment”
listeria can do it!
so in general, you collect bact samples and place them in the fridge to slow replication.
but NOT with Listeria because remember it likes colder temps for replication.
What is the most common manifestation of Listeria in humans?
Meningitis!
from drinking that unpast. milk
What is a classic source of Listeria infection? (where does it like to be when outside host)
contaminated silages!
so if you suspect an outbreak, test the silage.
What type of immune response do we want the host to have against Listeria?
CMI
remember it is a facultative intraceullar organism
T/F Live attenuated vaccines show some potential in cattle
FALSE! in sheep
What technique can be used to help grow Listeria?
cold enrichment
Under what conditions does Listeria grow best?
a. increased O2, decreased CO2
b. decreased O2, increased CO2
b. decreased O2, increased CO2
it doesnt like oxygen all that much
T/F L. monocytoegenes tests CAMP negative when cross-streaked with S. aureus
FALSE, its CAMP POSITIVE
remember :
L. monocytogens : CAMP+ with S. aureus
L. invanovii : CAMP+ with R. equi
T/F Erysipelothrix rhusiopathiae is coagulase positive.
True
T/F Most gram+ bacteria can not persist in the environment for a long time.
FALSE
most gram+ can persist in environment because of their peptidoglycan layer!
What species is most common to be infected with Erysipelothrix rhusiopathiae?
swine! oink oink!
What age of swine is most commonly infected with Erysipelothrix rhusiopathiae?
3months - 3 years
this is a period where swine is pushed for production. change diet, crowded - stress!
pigs 3mo have developed immune system
In Turkeys and sheep, which gender is more frequently infected with Erysipelothrix rhusiopathiae?
Males! because they are stupid and fight
In Erysipelothrix rhusiopathiae, what benefit is the capsule?
protects them from being killed by phagocytic cells and allows for intracellular replication.
- anti-pahgoctyic
- allows intracell rep
In Erysipelothrix rhusiopathiae, what is the purpose of neuraminidase?
adherence!
It cleaves sialic acid resideson endothelial cells, so bact can bind and then bact can break off to cause thrombus, endocarditis, meningitis