Bacterial GI Pathogens Flashcards
Are the e.colis that cause diarrhea the same ones that cause UTIs?
NO, we pathogen type e. colis
What are the 3 types of e.coli pathogen types?
- Commensal/symbiotic : no disease
- Extraintestinal disease (UTI, pneumonia, mastitis)
- Intestinal disease (diarrhea, vomiting)
What are the two major groups of intestinal e. coli pathogenecity?
Non-Toxigenic
Toxigenic
What are the Non-toxigenic E. coli pathotypes?
Enteropathogenic (EPEC)
Adherent and Invasive (AIEC)
What are the two types of Toxigenic E.coli pathotypes?
Enterotoxigenic (ETEC)
Shiga Toxin (STEC)
What species do EPECs infect?
All species including humans
What is the characteristic of EPECs?
Attaching and effacing lesions formed; EPEC attaches via intimin and injects effector proteins –> conformational change and decrease in surface area causing malabsorption
What is the mechanism of action of AIEC?
Invade enterocytes and survives within vacuoles of enterocytes
What are some characteristic pathologies of AIEC?
proliferative lesions associated with chronic inflammation
How do you diagnose AIEC?
Biopsy + FISH
What causes boxer dog colitis?
AIEC
What is the major cause of primarily neonatal diarreah in calves, lambs, and piglets?
ETEC
Why type of diarrhea do you see with ETEC infection?
Watery and non-bloody
what ate the 2 major toxins produced by ETEC
Heat liabile (HT)
Heat Stable (HS)
How does the Heat Labile toxin cause diarrhea?
Activates adenylate cyclase –> intracellular cAMP increased –> Prevent Na absorption & increase Cl excretion –> water follows salt
How does the Heat Stable Toxin cause diarrhea?
Activates guanylate cyclase
How do Shiga toxins work?
They bind to Gb3 (receptor on endothelial cells –> endocytosis –> removes and adenine from ribosome and halts protein synthesis –> host cell death
What type of diarrhea do Shiga toxins cause?
Bloody diarrhea
What is E. coli enterotoxemia?
Pig edema disease; causes edema, lateral recumbency, padding
Enterohemorrhagic E. coli (EHEC)
O157:H7 is the ptototype EHEC
What does EHEC do?
causes disease in humans… usually associated with fast food
What type of bacteria is Salmonella?
Aerobic (facultative anaerobic), gram negative bacilli, lactose non-fermenter on MacConkey agar
Salmonella is acid sensitive.. What does that mean?
Requires a very high infectious dose
What salmonella is the subspecies associated with mammalian or birds?
Salmonella entericay subsp. enterica
What salmonella is the subspecies associated with reptiles?
Salmonella enterica subsp. arizonae
What is the salmonella associated with typhoid fever in humans?
Salmonella enterica serovar Typhimurium
How is salmonella spread?
Fecal oral transmission
True/False: Salmonella is the leading bacterial foodborne pathogen
True
What is the most important risk factor in pets for salmonella?
Raw food diets
Have there ever been salmonella outbreaks in people from feeding raw food diets?
Yes
Can animals colonize salmonella and have no disease present?
Yes
What are the clinical signs of salmonella for NON host specialist strains?
-Clinical signs are variable
- Acute episodes of fever, malasia, anorexia, vomiting, abdominal pain, diarrhea
How to diagnose salmonella
isolation of bacterial from feces; let lab know you are particularly interested in salmonella and they will culture on enrichment broth in specialized media/PCR run on broth
Does a single negative test of salmonella rule out salmonella?
No, because it is shed intermittently
Can salmonella be harbored asymptomatically?
Yes
What is the treatment for salmonellosis with d+ only?
Supportive therapy; drug treatment an induce resistant strains and prolongs convalescent shedding… NO ABX
What is treatment for systemic disease of salmonellosis?
TMs, chloramphenicol, 3rd gen cephalo
What does campylobacter look like on a gram stain?
seagull
What is this
campy
What animals are the reservoir for campylobacter?
Birds; campy is commensal in the intestines of birds
How is Campylobacter transmitted?
VERY easily; fecal oral route, very low infectious dose as low as 500 cells
What are the two main species of Campylobacter?
C. jejuni – chicken, cattle, dogs
C. coli – pigs/dogs
What are the clinical signs of campylobacter?
may be asymptomatic, acute diarrhea, can be chronic diarrhea
What animals are most susceptible to campy infection?
Young puppies
How do we treat Campylobacter
Tylosin, erythromycin, azithromycin
