GI Infections Flashcards
What is dysentery? (as a symptom)
Diarrhoea with blood, pus and mucous
What bacteria are associated with bacterial diarrhoea? (5)
Camplyobacter Salmonella Shigella E.coli - various types Vibrio cholerae
Key toxins associated with GI infections? (toxin already formed in food) (4)
Clostirdium perfringens
Bacillus cereus
Staph aureus
Clostridium botulinum
Agent involved in antibiotic associated diarrhoea? (1)
Clostridium difficile
Viruses associated with GI infections? (2)
Norovirus
Rotavirus
Parasites associated with GI infections? (2)
Cryptosporidium
Giardia
What bacteria causes cholera?
Vibrio cholerae
Which virus is the the winter vomiting disease?
Norovirus
What virus causes diarrhoea in children and kills people in the undeveloped world?
Rotavirus
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
Are salmonella gram +ve or -ve? rods or cocci?
-ve rods, enterobacteriacae
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
How is salmonella diagnosed?
Culture or PCR
Tx for salmonella?
-ve rod
Ciprofloxacin or cefotaxime
Morphology of Shigella
Gram -ve rods enterobacteriacea
Shigella route of transmission, incubation period, symptoms, epidemiology, site
Strictly human only, spread by faecal oral route
Very infectios
Shigellosis symptoms: dysentry
Tx of Shigella diarrhoea?
ONLY for SEVERE diarrhoea
-ve rod
Ciprofloxin or azithromycin
Morphology of E coli
-ve rods- enterobacteriacae
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)
