This site is 100% ad supported. Please add an exception to adblock for this site.

Zoonotic Gram Negative Bacteria (Hull)


undefined, object
copy deck
The zoonotic bacteria are gram ______, and thus they (do/don't) have endotoxin (lipid A).
gram negative bacteria, do have endotoxin (lipid A)
What's the good news and bad news about these zoonotic infections?
Good: They are relatively rare causes of disease in the US (except for Rocky Mountain Spotted Fever being the most common)
Bad: If your patient does indeed have one of these, you aren't going to be thinking about these infections first off the bat
What 3 groups are the Rickettsia broken up into?
Coxiella, Ehrlichia, and Rickettsia
What is the causative agent of Rocky Mountain Spotted Fever? And where is this disease most common?
Rickettsia rickettsii. Most common in the Appalachia, Piedmont area, and Oklahoma
What is unique about the hemorrhagic skin lesions seen with Rocky Mountain Spotted Fever?
They are all over the body, but moreso they are characteristically located on the palms of the hands and soles of the feet (one of the few bacteria that have this ability).
What is the causative agent of Typhus fever?
Rickettsia prowazekii
What is the reservoir of rickettsia prowazekii (causes Typhus fever)? The vector?
reservoir = humans
vector = body louse
Why is Typhus fever a disease of war and famine?
Because during these times, there are huge displacements of people forced to wear the same clothes for long periods of time (ie flee from their homes with nothing but the clothes on their back). The body louse loves to live in the seams and folds of clothing, and will spread quickly under such conditions. Also, when these people die (those infected), others around may steal their clothes, helping propagate the spread of infection
What is the causative agent of Ehrlichiosis? And what is this becoming an increasingly recognized cause of?
*Ehrlichia chafeensis
*FUO = Fever of unknown origin
What happens to the body louse in Typhus fever that does not happen to the ticks that transmit Rocky Mountain Spotted Fever (Rickettsia rickettsii) or Ehrlichiosis (Ehrlichia chafeensis)?
The body louse itself gets infected and dies, therefore it cannot transmit the agent transovarily, whereas the ticks that give the other two do NOT die, and CAN transmit transovarily to their progeny.
With the 3 groups of Rickettsia, are the antibodies diagnostic? protective?
YES, YES!!!! The antibodies are both diagnostic and protective. Usually though, you have to wait around to see the Ab titer rise, and when you want to know sooner you just do a PCR test for the diagnosis.
What are the reservoirs of Rickettsia rickettsii (causes Rocky Mountain Spotted Fever)? Vectors?
*Reservoirs - dogs, rodents
*Vectors - ticks
What is the reservoir of Coxiella burnetti? Vector?
*Reservoir - cattle mainly, sheeps, and goats too
*Vector - inhalation
What is the causative agent of Q fever?
Coxiella burnetti
Why do we see a rise in Houston of Q fever around this time of the year?
Because of the rodeo, and people inhaling the Coxiella burnetti from the cows/bulls at the rodeo
Of the Rickettsia, which one causes a patchy pneumonia?
Coxiella burnetti causes a patchy pneumonia, that is actuall pretty much self limiting (will cure itself)
Infection from the zoonotics follows 3 scenarios...
1) direct contact with infected animal
2) direct contact with infected animal products (ie milk, cheese, etc)
3) bite of an arthropod that has fed upon an infected animal
How must you target the treatment of zoonotic infections and what is the only exception to this and why?
No penicillin, because you MUST target intracellular parasites with your antibiotics, therefore you need antibiotics that cross the eukaryotic cell membrane. The exception is wit Pasteurella multocida which can happily live in the bloodstream and spread this way, and in this case you could use penicillin to treat.
Which is the only zoonotic gram negative organism that isn't preferential to be an intracellular parasite?
Pasteurella multocida
Give two characteristics Brucella and Mycobacterium TB share in common?
1) Both are facultative intracellular parasites
2) Produce antibody in both cases that is diagnostic, but NOT protective
Describe the disease manifestation in Typhus fever
Vasculitis that results in rash, involvement of all major organs with multiple organ failure, shock, death
Describe the cycle of infection by the Rickettsia
They absorb to cells and penetrate into the endothelial cells, where they start a cycle of proliferation, cel lysis, and reinfection of healthy cells; results in vasculitis, occlusion of small vessels, microthrombi, and microhemorrhages (from damaging the endothelium)
What is the causative agent of Trench fever during WWI? And more recently, this has been implicated in endocarditis especially with homeless and malnourished persons
Bartonella quintana
What is a recognized agent in cat scratch disease? What another that is present in the oropharyngeal flora of cats?
Bartonella henselae (agent causing cat scratch disease) also can get infection from cat licking an already open wound, and Pasteurella multocida is a major oropharyngeal flora of cats and implicated also in cat scratch (cats licking paws then scratching) and also in cat bites.
Bartonella henselae causes characteristic skin lesions in AIDS pateints called...
Bacillary angiomatosis - basically looks like a tumor full of blood vessel growth
What are the reservoirs of Brucella?
goat (main one from story he told of the British soldiers in Malta who got sick from goat milk), cows, pigs, and dogs
Why/how does Brucella infection give an undulating fever?
During periods of growth inside the macrophages, there is no fever and patient is fine, but when they lyse and break out of cells looking to reinfect get a rise in the fever again along with subsequent remission when they enter cells again
What might you find in goat milk that can give you Malta fever?
Why were ranchers in Wyoming pissed off at Yellowstone?
Because the bison were carrying Brucella abortus, roamed out of the park, gave the disease to the ranchers' cattle, and the Brucella abortus in cattle causes fetal abortions (didn't have their calves).
Why were some people with Brucella being sent to psychiatric wards?
Because the symptoms with it are so broad and general, nothing really characteristic of Brucella (tough diagnosis to make... headache, depression, fatigue, malaise)
How infectious are Brucella? Francisella tularensis?
Both extremely infectious, takes only 10 bacteria to cause infection!
Why are people concerned of Francisella tulaensis as a means for biological terrorism?
Because it takes only 10 bacteria to infect (low infectious dose), and it has plague like symptoms (though fatality rate is much lower)
Francisella tularensis causes...
tularemia or rabbitt fever
Why is an image of a hunter commonly depicted with Francisella tularensis infection?
Because can contract the organism while skinning animal (may cut self and get the bacteria in their), or may get it on their hand then rub their eye (for oculoglandular presentation)
What is the most common presentation of Francisella tularensis?
ulceroglandular (ulcer with swollen nearest lymph node)

Deck Info