Bacterial infections of the GI Tract Flashcards
H/o frequent vomiting early in the course of a GI tract disease indicates what usually?
Viral infection
High fever, lack of vomiting, abdominal pain with bowel movements, and the presence of gross blood and mucus in the stool suggest what type of cause?
Bacterial
What is the bacteria that is associated with improperly canned food?
Clostridium botulinum
Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? : Clostridium botulinum
Anaerobic
Gram positive
Rod
Spores
What is the MOA of botulinum toxin?
Inhibit the release of Ach from synaptic vesicles
Exotoxin or endotoxin: botulinum
Exotoxin
What are the ssx of botulinumism?
Descending weakness and paralysis
Dysphagia
Diplopia
Is the botulinum toxin heat stable or labile?
Will denature at 100 C for 15 minutes
What is the treatment for botulinum intoxication? What is the prognosis?
IV antitoxin (horse antibodies). This only binds to active toxin however, and thus it is a slow recovery
Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? : Clostridium difficile
Anaerobic
Gram Positive
Spore forming
Rod
What is the most common nosocomial cause of diarrhea?
Clostridium difficile
What abx is the most common cause of C.diff infections?
Cephaolsporins
True or false: C.diff does not invade intestinal tissue
True (well, rarely anyway)
What is the MOA of the exotoxin that C.diff produces?
Exotoxins A and B are enzymes that glycosylate a G protein involved in actin polymerization
What are the gross features of pseudomembranous colitis caused by C.diff?
White-yellow plaques
Is C.diff diarrhea bloody?
No
What is the treatment for C.diff?
Oral Metronidazole or vancomycin
Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? Lactose fermenter?: Shigella dysenteriae
Gram negative enteric rods
Non-lactose fermenting
What is McConkey agar used for? What are the results?
Tests for lactose fermentation
Color change = lactose fermenter
How do you differentiate Salmonella from Shigella?
Shigella:
- Produce no gas from fermentation
- Do NOT produce H2S gas
- They are non-motile
What type of diarrhea does shigella produce: bloody or not? Why?
Bloody– invasion of the intestinal epithelium causes blood and pus to form
What is the MOA of shigella? (does it produce a toxin? Does it invade cell walls)?
Produce a toxin and invade intestinal cell walls
What is the MOA of shigella toxin?
binds to ribosomes and halts transcription
What is the treatment for shigellosis?
IVF and lytes
If severe, fluoroquinolones (e.g. cipro)
Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Motile? Lactose fermentation?: Salmonella?
Gram negative rods
NO lactose fermentation
Produce H2S
Motile
What are the two species of Salmonella that cause few GI symptoms?
S. Typhimurium
S. Enteritidis
What are the three types of Salmonella infections?
Enterocolitis
Enteric fever
Enteritidis
Which bacteria are not susceptible to HCl?
Shigella**
Campylobacter jejuni