Bacterial Infections of the GI Tract 3 Flashcards
1
Q
Vibrio spp:
- Gram stain
- Aerobic abilities
- Shape
- Free living in _ ?_
5. _ _ temperature range of growth
- Requires _ _ _ _ for growth (compound)
- Grow at a _ _ range of pH
- Susceptibility to stomach acid
A
- Gram negative
- Facultative anaerobes
- Comma (curve shaped)
- Free living in water
- **Broad ** temperature range of growth
- Requires sodium chloride for growth
- Grow at a wide/broad range of pH
- Definitely susceptible to stomach acid which is why a high infectious dose is needed to cause illness
2
Q
Vibrio cholerae
- Symptom range
- Incubation period
- Duration
- Key symptom
- How much fluid can a patient lose?
- What does the diarrhea look like
- What actually kills the patient?
A
- Symptoms range from asymptomatic to severe watery diarrhea
- Incubation is 2-3 days
- Duration is up to 7 days…unless it kills you
- 5-25% of patients develop severe watery diarrhea
- Can lose up to 250ml/kg body weight/day
- Diarrhea looks like rice water
- Dehydration can kill within hours
3
Q
Vibrio cholerae
- How does cholera spread?
- Long-term immunity?
- Associated with what?
- Typing is based on what?
- What type caused the first 6 cholera pandemics?
- Which one is causing the 7th?
A
- Spreads through contaminated water
- Long-term, O antigen specific immunity
- Associated with epidemics, pandemics, and natural disasters
- Typing is based on O antigens (O1-O200)
- Type O1 caused the first 6 pandemics
- El Tor biotype is causing the 7th
4
Q
Vibrio Cholerae
- How does v. cholerae adhere to intestinal epithelial cells?
- How does the cholera toxin work?
- Pathogenesis is similar to what other disease?
A
- Toxin co-regulated pilus (TCP) helps v. cholerae adhere to intestinal epithelial cells
- Cholera toxin is an AB toxin. The toxin causes an activation of adenylate cyclase which increases the amount of cAMP. An increase in cAMP causes massive efflux of sodium, chloride, potassium, water, and bicarbonate.
- Very similar to ETEC LT toxin
5
Q
Vibrio Cholerae
- Diagnosis method and what requirements are being tested for
- Treatment
- How high is the mortality rate without rehydration therapy
A
- Diagnosis made by culture on differential media. Vibrio Cholerae is a facultative anaerobe, has a wide temp and pH growth range, and requires sodium chloride
- Treatment is rehydration therapy (oral and IV)
- Mortality rate can reach 90% without adequate rehydration
6
Q
Vibrio parahaemolyticus
- Inflammatory or not so much?
- Primary symptoms (5)
- Virulence/pathogenesis
A
- Definitely inflammatory
- Common symptoms are explosive watery diarrhea, nausea, vomiting, abdominal cramps/discomfort, and a low grade fever
- Kanagawa** hemolysin** induces chloride secretion so watery diarrhea
7
Q
Vibrio parahaemolyticus
- Vibrio parahaemolyticus is the most common cause of _ _ _ _ in Japan and SE Asia
- _ _ associated _ _ in the U.S.
- Associated with the consumption of _ _ _ _
A
- Vibrio parahaemolyticus is the most common cuase of **bacterial gastroenteritis **in SE Asia
- Seafood associated gastroenteritis in the U.S.
- Associated with the consumption of raw shellfish
8
Q
Vibrio parahaemolyticus
- Treatment and Prevention
A
Vibrio parahaemolyticus is self limiting. Prevention would be properly cooking shellfish
9
Q
Yersinia enterocolitica
- Gram stain
- Shape
- Most isolates are virulent or avirulent?
- Spread by ingestion of contaminated _ _ and _ _ especially, _ _
A
- Gram negative
- Shape is coccobacilli
- Most isolates are avirulent
- Spread by ingestion of contaminated water and food, especially pork
10
Q
Yersinia enterocolitica
- Range of symptoms
- Duration of disease
- Treatment
A
- Range of symptoms is from fever, abd cramps, and watery diarrhea all the way to explosive, bloody diarrhea
- Duration is 1-2 weeks
- Treatment: disease is usually self-limiting. If not then TMP-SMZ or aminoglycosides. That last part wasn’t part of the lecture
11
Q
Yersinia enterocolitica
- Pathogenesis
- Pathogenesis is similar to what other disease
- Produces what type of toxin?
- Diagnosis
A
- Pathogenesis is poorly understood but it does attack M-cells
- Process is similar to Salmonella but injects YOPs (yersinia outer proteins) via T3SS mechnism rathat than SPSs
- Produces a heat-stable enterotoxin
- Diagnosis is via stool culture
12
Q
Clostridium difficile
- Where does C. diff do its dirty work?
- Gram stain
- Aerobic abilities
- Invasive or not so much?
- Inflammatory or not so much?
- What does C. diff do that explains why is spreads to easily and why it is so hard to kill?
A
- C. diff does its dirty work in the large intestine
- *Gram stain positive*
- Anaerobic
- Non-invasive
- Definitely inflammatory
- C. diff is spore forming which makes it so difficile…HAHAHAHA!
13
Q
Clostridium difficile
Describe the symptom varying and degrees of virulence
How does someone usually acquire C. diff?
A
Asymptomatic carriage < CDAD (C. diff associatied diarrhea) < pseudomembrane colitis < fulminant colitis with toxic megacolon
Typically a patient is hospitalized and a few things happen: they come into contact with a contaminated HCW after receiving broad spectrum antibiotics which usually happens after surgery. The normal gut flora are killed off and, if immunosuppressed, C. diff with raise its ugly head
14
Q
Clostridium difficile
Pathogenesis: which toxins produced (2) and how do they work
Diagnosis
Treatment
Prevention
A
- Toxin A and Toxin B produced which cause damage to intestinal mucosa by disrupting cellular cytoskeletons which causes diarrhea
- Diagnosis is via ***TOXIN* **detection in stool. Culture is basically useless
- Treatment is ORAL vancomycin or metronidazole
- Prevention/Treatment is fecal transplant
15
Q
Enterohemorrhagic E. coli (EHEC)
- Gram stain
- Aerobic abilities
- Typical animal reservoir
- How does it normally pop up? Associated with which contaminated food?
A
- Gram negative
- Facultative anaerobe
- Usually cattle
- Sporadic cases and outbreaks in developed world. Typcially associated with contaminated beef or vegetables (because washed with contaminated water)
