Cholera, Campylobacter, Helicobacter Flashcards
vibrio cholerae
causes cholera
motile gram negative fermenter, comma shape, polar flagellum
what strain of v. cholerae cause epidemics
O1- 2 types- classical and hemolytic (responsible for all cholera in the last decade)
what effect does acid have on v. cholerae?
inactivates some but not all
how does v. cholerae infect?
enters small bowel and bind to epithelium
uses toxin coregulated pilus- causes agglutination w other bacteria
cholera toxin
endocytosed into epithelium- binds to GM1 ganglioside
neurominidase is an enzyme that modifies the host glycosugars to make better binding sites
stimulates cAMP causing massive fluid loss
how does cAMP cause fluid loss?
activates CFTR
villus cells- decreased NaCl absorpotion
secretory cells- increased Cl and HO3 secretion
cholera symptoms
painless, odorless profuse water diarrhea (rice water stool)
isotonic volume loss, dehydration, H2O
cholera treatment
rehydration
antibiotics can reduce duration from 5-10 to 1-3 days
doxycycline or azithromycin (children/pregos)
where is cholera a problem
associated w/ poverty and inadequate sanitation
endemic in south america, africa, south central/south east asia
currently a pandemic
what is the cause of the recent endemic in south america?
aid workers coming for relief of haiti earth quake brought from nepal
how is cholera generally contracted?
contaminated water, shellfish, seafood, rice
cholera vaccine
both inactive and live
inactivated- only 70% effective, not recommended for travel
live- unproven in field, only critical trials
what season causes cholera outbreaks
rainy seasons- spring and fall
vibrio paraemolyticus
invasive gastroeneteritis from contaminated shellfish
vibrio vulnificus
infections in wounds from contaminated shellfish/seawater in people w/ liver disease
what media should be used to isolate cholera
TCBS- high in salt, high in bile salts
cholera turn greenish d/t thiosulfate
campylobacter morphology
gram negative rod, curved
where does campylobacter infect?
contaminated food and water. infects small and large bowel and causes invasive inflammation
rarely enters the bacteremia
campylobacter epidemiology
zoonotic- transmitted from animals, especially poultry. human to human is rare
peak in summer and early fall
most common cause of diarrhea in the world
campylobacter is microaerophilic
ok
campylobacter incubation period
3-5 days
symptoms of campylobacter
prodrome fever, malaise, headache
then
abdominal pain and diarrhea lasting a week
guillaim-barre syndrome
1/1000 people develop autoimmunity to their own nerves
campylobacter infectious dose
500
