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41 Cards in this Set

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  • Back
define zoonoses
infectious agent usually infects an animal, but human has gotten in the way as an accidental host; basically we are the dead end hosts
what is the morphology and physiology of Listeria monocytogenes?
gram pos facultative intracellular pathogen. CAN GROW AT 4 deg C!!!
what are the symptoms and disease caused by L. monocytogenes?
mild flu like in healthy ppl, but in immunocompromized, neonates, and pregnant women it can cause serious disease like meningitis
what are the reservoirs of Listeria?
ubiquitous in soil, water, vegetation, intetines of mammals, birds, fish, insects, note that our intestines are asymptomatic carries
how is Listeria transmitted?
ingesting contaminated food products, can be raw veg too... but need like 10^9 to be infected. can be transfered from mom to child transplacentally or in infected birth canal. rare cross infection in NI nurses...
what is the epidemiology of Listeria?
worldwide, has declined as food regulations have tightened
what is the route of infection in Listeria?
ingestion - crosses mucosal barrier at peyer's patch, invades mesenteric lymph nodes - blood stream - targets liver to replicate within hepatocytes - neutros come in, hepatocytes lyse, prolonged bacteremia, placenta and brain are exposed
describe the clinical disease of Listeria in neonatal infections.
CMI is mildly impaired, this is probly why preg women can get infected. if infects child in womb can get abscesses and granulomas in multiple organs resulting in stillbirth or neonatal death. early onset from aspiration of infected amnionic fluid leads to sepsis. late onset from colonization of neonate by org in vagina can cause meningitis
describe the adult clinical disease of listeria.
asymptomatic, flu like, some GI symptoms - all self limiting. Listeria likes the brainstem and meninges... and will give meningitis to immunocompromised and preg women. bacteremia can occur and can kill immunocompromised and neonates as well as cause preg women to abort. brain stem encephalitis can occur which has a high mortality and infects healthy adults (unusual thought), brain abscesses and endocarditis can also occur.
describe the pathogenesis of Listeria
facultative intracellular, epi cell invasion by internalin A, phagocytosis by professional phagocyte, listeriolysin O and phospholipase lyse vacuole membrane and bac gets into cytoplasm and stays there. ActA promotes movement of bac to cell surface via actin polymerization, then promotes filopodia of cells so it can be taken up by another cell. Need CMI to get rid of this bad boy bc he stays intracellular for so long
what are the treatment and prevention of Listeria?
for at risk individuals avoid soft cheeses, reheat ready to eat foods, wash raw veggies, cook raw food from animals, penicillin or ampicillin with or without gentamycin. Early antibiotic treatment of infected preg women can increase chances of delivering healthy child... no vaccines
what are the properties of Pasteurella multocida?
gram neg coccobacilli, facultative, encapsulated, extracellular
what is the epidemiology of pasteurella?
worldwide with a reservoir in the oropharynx and GI of healthy dogs, cats, and other animals
how does one become infected with pasteurella?
bite/scratch from animal, cat scratch is most common.
describe the clinical diseases caused by Pasteurella.
skin, joints, and soft tissues can become inflamed, some may have regional lymphadenopathy, rarely an abscess, and even more rarely septic arthritis. Resp tract infections are second in frequency to above, can cause upper and lower tract infections, usually pneumonia is seen when pt has another lung disease. CNS infections are infrequent, usually neonates and elderly, meningitis, most do not have invasive injury
what are the virulence factors of pasteurella? treatments?
fimbrae to adhere to upper resp epi cells, antiphagocytic capsule, leukotoxin impairs cellular response in lung tissue. treat with penicillin, if spetic arthritis, may need frequent drainage and antimicrobial therapy
what are the basic properties of brucella?
intracellular, nonencapsulated, gram neg aerobe, lotsa animal reservoirs and causes nonspecefic symptoms of serious disease
what does Brucella do in its reservoirs?
stays as a chronic lifelong infection. replicates within the reproductive organs, causing sterility and abortion, large numbers shed in milk.
how can ppl aquire Brucella?
breaks in skin, inhalation of animal tissue, ingestion of unpasteurized dairy products
what is the progression of Brucellosis?
enter body through abrasion or mucosa, macs ingest them, replicate in the macs, macs go to the lymph nodes, other macs become infected, spreads via lymphatics and blood, serum can opsonize it but the cidal activity is not effective, thus it can grow in the blood stream, organs become seeded with brucella
how would you get spontaneous resolution of brucellosis?
CMI will use ACTIVATED macs, brucella can replicate in normal macs
describe the clinical disease of brucellosis.
non specefic symptoms and very hard to diagnose, can see unusual symptoms like depression, neuroses, strange taste in mouth. any organ may be involved, systemic symptoms, GI, inability to concentrate. acute or chronic symptoms may recur for months or years
what are the complications of brucella?
GI (most of pts), liver (almost all pts), skeletal system (less than half) including arthritis and osteromyelitis, CNS (rare): meningitis, encephalitis, brain abscess
what causes the majority of fatalities in brucella?
endocarditis (even though its only in 2% of cases)
what brucella orgs cause the most clinical disease?
B. melitensis and suis
what are the brucella virulence factors?
replicate within phagocytic cells, polysaccharide linked LPS (needed for survival in phagocytic cells), can block lysosomal fusion, type IV secretion
how do you diagnose brucella?
blood specimens plated on blood agar, gram neg non motile aerobic rod shaped bac seen on stain, serology via agglutination to look for IgG
how do you treat brucella?
doxycycline with rifampin for 6 wks or trimeth/sulfa and rifampin in preg women or chiodren. no human vaccine and cattle/goat vaccines are virulent for humans.
what are the basic properties of Francisella tularensis
gram neg coccobacillus, lipid capsule, aerobe, rare, facultatively intracellular, ID is 10 to 50 if inhaled, 108 + via ingestion, can be aerosolized, spread by a arthropod that feeds on rodents, can get it from arthropod bite or rodents, biowarfare
distribution and reservoirs of Francisella?
worldwide, hundreds of dif vertebrates, in US it is seen in wild rodents
how is Francisella transmitted?
arthropod bite (blood feeding flies, ticks, mosquitoes), contact with infected animal parts, ingestion of contaminated water, no uman to human spread
describe the clinical disease caused by Francisella that is not tularemia or the ulceroglandular form.
begins with fever, chills, headache, malaise, anorexia, and fatigue. see recurring fever without treatment that averages for a month, diagnosis is difficult bc about 1/4-1/2 of pts do not recall animal exposure
describe the ulceroglandular form of the disease caused by Francisella.
few days after bite, bac multiplies, papule formed, ulceration a few days later, bacs go to regional nodes, tender lymphadenopathy, bacteremia, PMNs and macs recruited but are ineffective, necrosis of lungs and nodes, as necrose expands the adjacent BV's may thrombose, recovery depends on CMI.
describe pharyngeal tuleremia.
variant of ulceroglandular, invades through oropharynx, severe throat pain, exudative pharyngitis, tonsilitis, ulcers
describe pneumonic tularemia.
dominated by pulmonary infection, inhalation of infectious aerosols or secondarily hematogenous spread to lung, high morbidity and mortality, secondary pneumonia may complicate other syndromes,
describe typhpoidal tuleremia
febrile, no prominent lymphadenopathy, no apparent portal of entry, difficult to diagnose, most pts have serious underlying medical condition, diarrhea is common, dramatic presentation including systemic symptoms, nause, vomiting, sore throat, headache, systemic signs of sepsis
describe oculoglandular tuleremia
eye contamination from aerosol, fingers, etc. painful conjunctivitis and regional
describe the pathogenesis of Francisella
resistant to serum killing, intracellular of reticuloendothelial system (lives in macs), resistant to neutro killing, inhibits phagosome-lysosome fusion, lipid capsule associated with virulence, host rely on CMI
what are the outcomes of tuleremia?
suppurtion of lymph nodes when involved if they are not treated. can lead to months of debility and persistant fatigue like brucella, death rate is only 4% due to antibiotics
what are the lab techniques for diagnosing Francisella
need biohazard hoods when working around this fella, tell the lab bc they need cysteine blood agar/glucose cystein agar, slow growth of 1 wk +, agglutinates with antibiotics, direct fluroescent antibody stain
what are the treatment, control, and prevention methods for Francisella?
streptomycin is drug of choice - watch out for toxicity, gentamycin is a good alternative, wear gloves when chopping up wild animals, insect repellants, remove those ticks, work in biosafety cabinent when working with the org, there is a live attenuated vaccine that can lessen severity of the disease that is administered to lab workers but not to the general public