GI tract infections

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  • Created by: Amh
  • Created on: 08-04-16 17:39
What are gut defence mechanisms
Acidic pH in stomach, phagocytosis, and IgA in the gut, peristalis of the gut, and normal microflora
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When are gut defecnces comprimised
Age illness drugs
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What are the clinical features of GI infections
Diarrhoa maybe dysrentery, nausea, comitting, abdominal pain, fever headache
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What type of campylobacter commonly cause GI infections
C jejuni C coli
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whee do get campylobacter infections from
eating undercooked poultry
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What is the clinical manifestation of a campylobacter infection
Causes bloody diarrhoea with fever and abdominal pain 2 – 5 days after ingestion
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What is the appearance of campylobacter
gram negatice rod seagull
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Is campylobacter fastidious
yes requires charcole cefoperazone, desoxycholate, amphotericin agar and microaerophillic incubation at 42 degreees cent
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What species of salmonella cause GI infection
S enteritidis S typhi S paratyphi
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outline typhoid fever
Incubation period 2 weeks, Septicaemia, high fever, constipation rather than diarrhoea – ‘Rose spots’ on skin - rash
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How do you diagnose Salmonells
First use selenite broth then culture onto XLD
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How salmonella appear on XLD
red colonies black centres because they produce H2S
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Does salmonella ferment lactose
No
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What serologies do you do to confirm salmonella
Poly ‘O’ and ‘H’ antisera • Specific antsera for O and H types • Kauffmann – White Scheme
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What are some key shigella species
S. sonnei, dysenteriae, flexneri, boydii
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why does shigella spread so easily
there is a very small infective dose
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How does shigella appear on XLD
Red no black dots
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What are the characteristics of clostridia perfringens
Anaerobic gram positive rods sporulate and release enterotoxins
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What are the symptoms of clostridia perfringens infections
Watery diarrhoea – Abdominal cramps – Vomiting – Fever.
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How do we demonstrate presence of toxin
Nagler plate
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Is Clostridium difficile part of our normal flroa?
yes
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When does C difficile become an issue
when antibiotics deplete the other flora and produces toxins A and B
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What are the severe complications of C fifficile colitis
– progressing to pseudomembranous colitis – Toxic megacolon Colonic perforation, acute abdomen, sepsis, death
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What is Bacilus cereus also known as
Chinese Restaurant Syndrome
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what is the disease caused by
cells vegetating and releasing toxins, we ingest toxins
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What are the symtoms of this disease
Severe vomiting 1 – 5 hrs later (emetic toxin) • Followed by diarrhoea 8 – 16 hrs later (diarrhoeal toxin)
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What are the characteristics of B cereus
is grows aerobically as blue colonies on B. cereus agar
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What is another toxin mediated disease
S aureus
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How long does it take to see symptoms from S aureus
1-6 hours
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How do you diagnose S aureus GI infection
clinically can use PCR for enterotoxin
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What forms of e coli can cause diseases
Enteropathogenic E. coli (EPEC) – Enterotoxigenic E. coli (ETEC) • Travellers diarrhoea – Enteroinvasive E. coli (EIEC) – Enteroaggregative E. coli (EAEC) – Diffusely adherent E. coli (DAEC) • Verotoxigenic E. coli (VTEC)
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What does verotoxigenic ecolicause
Shiga like toxin, Haemolytic uraemic syndrome
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What does Haemolytic uraemic syndrome lead to
haemorrhagic colitis, acute renal failure, thromobocytopenia
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What is E coli asscoiated with
undercooked beef burgers
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What is the commonest strain of VTEC
0157
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Does 0157 ferment sorbitol
no
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Which comma shaped gram negative bacteria is another toxin mediated disease
Vibrio species
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What are 2 types of vibrio that cause disease
V. Cholerae • V. parahaemolyticus
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Where are you most likely to get V. parahaemolyticus from
Shellfish
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How do you culture and identify vibrio
on TCBS media (yellow colonies) gram negative
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How does the cholera toxin cause disease
it deregulates cell membrane causing an elecktrolye efflux
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Why is it hard to culture and identify pathogen microorgansims
Because we use stool samples which have a great deal of normal flora, shigell and salmonella are both eneterobacteriaceae, and many need different enrichment and media
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What is a common cause of viral gastroenteritis
NoRovirus
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Are viral GI infections serious
not usually
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What is the treatment for gi infections
rehydration, maintain electrolytes, Ciprofloxacin / erythromycin
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How do you trea C dif
stop antibiotics, faecal transplant / Metronidazole / vancomycin
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Can you vaccinate against gi infections
yes against ETEC and rotavirus
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When are gut defecnces comprimised

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Age illness drugs

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What type of campylobacter commonly cause GI infections

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whee do get campylobacter infections from

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