GI Infections Flashcards by Rebecca Rooney

What is dysentery? (as a symptom)

Diarrhoea with blood, pus and mucous

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What bacteria are associated with bacterial diarrhoea? (5)

Camplyobacter
Salmonella
Shigella
E.coli - various types
Vibrio cholerae

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Key toxins associated with GI infections? (toxin already formed in food) (4)

Clostirdium perfringens
Bacillus cereus
Staph aureus
Clostridium botulinum

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Agent involved in antibiotic associated diarrhoea? (1)

Clostridium difficile

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Viruses associated with GI infections? (2)

Norovirus

Rotavirus

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Parasites associated with GI infections? (2)

Cryptosporidium

Giardia

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What bacteria causes cholera?

Vibrio cholerae

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Which virus is the the winter vomiting disease?

Norovirus

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What virus causes diarrhoea in children and kills people in the undeveloped world?

Rotavirus

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Difference between intoxication and infection?

Intoxication is consuming premade toxins in food, infection is ingesting the bacteria themselves

Intoxication has shorter incubation 2-12 hrs

Infection has incubation of days

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Are salmonella gram +ve or -ve? rods or cocci?

-ve rods, enterobacteriacae

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Salmonella route of transmission, incubation period, symptoms, epidemiology, site

Symptoms: N and V, cramps, NON-BLOODY DIARRHOEA

Incubation: 6h-2d

Duration: a week

Transmitted to humans via contaminated food and person to person (and animals)

Both illeum and colon

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How is salmonella diagnosed?

Culture or PCR

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Tx for salmonella?

-ve rod

Ciprofloxacin or cefotaxime

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Morphology of Shigella

Gram -ve rods enterobacteriacea

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Shigella route of transmission, incubation period, symptoms, epidemiology, site

Strictly human only, spread by faecal oral route

Very infectios

Shigellosis symptoms: dysentry

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Tx of Shigella diarrhoea?

ONLY for SEVERE diarrhoea

-ve rod

Ciprofloxin or azithromycin

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Morphology of E coli

-ve rods- enterobacteriacae

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E coli route of transmission, incubation period, symptoms, epidemiology, site

6 types of e coli (this is enterohaemorrhagic e coli causing HUS)

Zoonotic spread from farm animals. Associated with eating undercooked mince, or raw milk

Causes BLOODY diarrhoea with abd. cramps but no fever

Outbreaks and sporadic cases

Test for e coli O157:H7

Stool test for shiga toxins which are produced by the bacteria

Complication of e coli O157:H7?

HUS

Haemolytic uraemia syndrome

Increased RBC breakdown leading to kidney failure and uraemia

Tx for e coli O157:H&?

NONE, diarrhoea will get worse or HUS will develop

Give fluids

Other types of e coli may be given antibiotics eg trimethoprim, fluoroquinolone

Morphology of Vibrio cholerae?

Gram -ve comma shaped bacteria

Vibrio cholerae route of transmission, incubation period, symptoms, epidemiology, site

Only in humans, has caused epidemics and pandemics,

Acquired from infected water supplies

Short incubation

Toxin causes excess fluid loss and painless, profuse, watery diarrhoea

Morphology of Campylobacter

Curved or S-shaped grame -ve rods

Campylobacter jejuni route of transmission, incubation period, symptoms, epidemiology, site

Most common cause of food related illness in UK Large animal reservoirs and spread in food chain IP: 3-10 days Causes FEVER, abd pain, BLOODY DIARRHOEA Can cause Guillan Barre syndrome

Tx of campylobacter enteritis

Frequently self limiting -ve rod Clarithromycin of ciprofloxacin

Morphology of C difficile

Gram POSITIVE, sporing, anaerobic rod

What toxins does C difficile produce?

Toxins A and B

What is pseudomembranous colitis?

Most sever form of C difficile, where there is a pseudomembrane present on the colon surface, made of inflammatory cells, fibrin and necrotic gut cells

Key diagnostic test for C difficile?

Stool sample for presence of toxin | however healthy individuals may carry the bacteria and be okay, so consider whole clinical picture

Tx of C difficile?

Nursing with barrier precautions Discontinue unnecessary abx Oral vancomycin or oral metronidazole

Morphology of cryptosporidium parvum?

Parasite

Cryptosporidia route of transmission, incubation period, symptoms, epidemiology, site

Moderate to severe diarrhoea Self limiting except in immunocompromised Transmission via drinking water (even chlorinated) contiminated by oocysts from humans or animals Only immunocompromised need treated

Morphology of Giardia lamblia

Parasite

Giardia route of transmission, incubation period, symptoms, epidemiology, site

Can cause chronic infection NO BLOOD IN DIARRHOEA Water/food/faecal oral

What causes traveller's diarrhoea?

E coli

Bacillus cereus route of transmission, incubation period, symptoms, epidemiology, site

Toxin in food (esp. fried rice) Vomiting 2-3 hours post ingestion (type 1) Diarrhoea 10-12 hours after ingestion

Staph aureus route of transmission, incubation period, symptoms, epidemiology, site

Enterotoxin A in food contaminated by human carriers Toxin acts on CNS to causes vomiting within 2-6 hours Vomiting not a feature Self limiting (24 hours)

Clostridium perfringens route of transmission, incubation period, symptoms, epidemiology, site

GI tract of animals and the environment as heat resistent spores. Grow in food at room temp eg meat sauces and gravies Watery diarrhoea

Botulism route of transmission, incubation period, symptoms, epidemiology, site

No nausea or diarrhoea Toxins in canned food Causes flaccid paralysis to progressive muscle weakness to respiratory arrest NEEDS ANTITOXIN

In camplobacter gastroenteritis, blood in faeces is rare

False, occurs in 50%

Importance of camplobacter gastroenteritis has only become well recognised in recent decades

True, began to be cultured in 1980s

Reactive arthritis is a recognised complication of salmonella infection

True

Most strains of E coli in the intestine have the potential to cause diarrhoea

False. Most do not (except enteropathic e coli, enterohaemorrhagice e coli etc)