Gastroenteritis Flashcards
what are 3 crucially important pathogens?
1) campylobacter
2) salmonella
3) E. coli 0157
what are 6 GI infection risk factors?
1) malnutrition (micro-nutrient) deficiency
2) closed/semi-closed communities
3) exposure to contaminated food/water/travel
4) winter congregating/summer floods
5) age<5, not breastfeeding
6) older age
what are 4 other risk factors?
1) acid suppression
- yersinia enterocolitica, helicobacter pylori tolerant of acid
- C. difficile more common with acid suppression
- Vibrio cholera, non typical salmonella, campylobacter, E. coli
2) immuno-suppression
- salmonella, campylobacter, shigella shed for longer
- other organisms that are uncommon in immune competent
3) micro-biome
4) genetics
- IL8 promoter variant & servere C. difficile
- O blood group& vibrio cholera
what are 6 bacterial factors involved in GI infections?
1) adherence/attached to GI mucosa
2) cellular invasion
3) production of exotoxins
4) changes in epithelial cell physiology
5) loss of brush border digestive enzymes, and/or cell death
6) increased intestinal motility, next fluid secretion, influx of inflammatory cells, and/or intestinal haemorrhage
describe innocuous size that makes picking up GI infections likely.
- low infectious doses make spread easier
- pH affects required dose
what is diarrhoea?
= >3 unformed stools/day
= no the cause
- exclude laxative use/abuse & use of drugs/stimulants
- departure from normal bowel habits
- use Bristol stool char
what is gastro-enteritis?
= inflammation of intestines, particularly colon, causing diarrhoea, associated with blood and mucosa
what are 2 examples of bacteria that could cause gastro-enteritis?
- shigella
- campylobacter
what systemic things is gastro-enteritis associated with?
- fever
- abdominal pain
- rectal tenesmus (sense of incomplete defaeceation)
describe the duration of gastro-enteritis?
acute duration < 2 weeks
if gastroenteritis affects the large bowel describe the volume affected?
smaller volume
what can mimic appendicitis and why?
= yersinia enterocolitica
- as it may invade mesenteric nodes
what 4 things does bacteria need to multiply?
- Time
- temperature
- food source
- moisture
what can survive adverse conditions?
= spores
what happens in the kitchen that promotes bacteria growth?
- cross contamination of raw & cooked food
- preparation food too far in advance
- inadequate heating & cooling
- contaminated environment & equipment
- poor personal hygiene
what is gastroenteritis caused by?
= eating food contaminated with micro-organisms, toxins, poisons
e. g. bacteria, viruses, parasites
- invasion of tissue +/- toxin production
what effect does cholera have on volume of diarrhoea?
= large volume of diarrhoea
describe the history most commonly associated with gastroenteritis?
- diarrhoea, blood, mucus, time course
- other GI symptoms
- travel, contacts = human and animal
- food history = storage, re-heating, washing
- age of patients
- co-morbitidites
describe what infections would be common with foreign travel, recent camping, recent antibiotics, daycare exposure, exposure to raw seafood, anal sex, HIV positive status and outbreaks.
Foreign travel
- travellers diarrhoea = enterotoxigenic E. coli
- Southeast Asia = vibrio species
- South America, Africa, Asia = rotavirus
Recent camping
= giardia
= aeromonas
= cryptosporidium
Recent antibiotics
= C. difficile
Daycare exposure
= rotavirus
Exposure to raw seafood
= non-cholera vibrio
Anal sex
= shigella
= campylobacter
= salmonella
HIV positive statua
= mycobacterium avium-intracellular complex, mixrosporidia, cytomegalovirus, giarida
Outbreaks
- cruise ships = noro
- contaminated water, food = salmonella, E. coli, campylobacter
what 2 bacterias have a short incubation time of 1-6hours?
1) bacillus cereus (gram + bacillus)
- starchy foods
- heat resistance spores
- profuse vomiting
- reheating rice
2) staphylococcus aureus (Gram + coccus)
- performed toxin in food, rapid absorption
- acts on vomiting centre in bran
- foods left in room tempt
- milk/meat/fish
what do all stooges get tested for?
= salmonella = shigella = campylobacter = E. coli 0157 = cryptosporidium
All > 4years stools get;
= C. difficile
what are the 4 groups associated with Shigella sp?
group A
= S. dysenteriae
group B
= S. flexneri
group C
= S. boydii
group D
= S. sonnei
what does shiga toxins do?
- binds to receptors on renal cells, RBC and others
- inhibiting proteins synthesis
- causes cell death
what toxin can produce E. coli?
= shiga-toxin producing E. coli
what symptom is associated with E. coli 0157 infections?
= bloody diarrhoea
= bloody per rectum
describe how one would acquire E. coli 0157?
- very low infectious dose
- food (raw milk, water)
- person to person
- animal contact
= children and elderly at risk of complications
describe the incubation time for E. coli 0157?
= 1-14 days
what can E. coli 0157 produce?
= verotohxin (VTEC)
what is HUS?
= haemolytic uraemic syndrome (HUS)
what is HUS associated with?
- abdominal pain
- fever
- pallor
- petechiae
- oliguria
- bloody diarrhoea
describe the cell count that would be found in HUS?
- high white cells
- low platelets
- low HB
- red cell fragments
- LDH > 1.5
- may develop after diarrhoea stopped
how would you investigate HUS?
- send stool cultures samples
- send U&E, FBC, film, LFT, clothing, urine, dehydrogenase
Gastroenteritis 2
Gastroenteritis 2
what are 4 other E. coli pathotypes?
1) enterotoxigenic (ETEC)
2) enteropathogenic (EPEC)
3) enteroinvasive (ELEC)
4) enteroaggregative (EAIC)
describe enterotoxigenic (ETEC).
- produces heat labile and heat stable toxin
- heat stable toxin similar to choler and yersinia toxins
- travel related
describe enteropathogenic?
- attaching and affecting lesions = no toxins, not invasive - synthesises, secretes & inserts its own receptor into cell membranes - non breastfed children - can be asymptomatic
describe enteroinnvasive?
= watery diarrhoea, rare dysentry
- demonstrates invasion
- sereny test
describe entero-aggregaive?
- travellers diarrhoea
- cryogenic, secretogenic, pro-inflammatory
True or false. All diarrhoea (blood or not) is infectious?
False.
describe the incubation times for campylobacter?
- 16-48hours
describe how campylobacter is spread?
- spread sporadically (rarely outbreaks)
- food:poultry
- small pathogen number
- food, hygiene (raw poultry especially)
- macrolide
- less likely to spread person to person
- invasive
- pain, blood, fever
= most common
what are some campylobacter human pathogenic strains (enteric)
- C jejunisubspeciesjejuni
- C jejunisubspeciesdoylei
- Campylobacter coli
- Campylobacter upsaliensis
- Campylobacter lari
- C fetussubspeciesfetus
- Campylobacter hyointestinalis
- Campylobacter concisus
describe the incubation time for salmonella enteritidis?
= 12-48hours
how is salmonella enteritidis spread?
- food: poultry, meat, raw egg
- animal gut, multiplies in food
- toxin and invasion
- D&V, blood, fever
describe the serotyping of salmonella?
- > 1500 different types: group A to Z based on antigen of body (O antigen)
= a serotype helps pinpoint source of infection
= groups B, C and D are most commonly locally
describe the incubation time for listeria monocytogenes?
= 9-48hours
describe the incubation time for listeria monocytogenes?
= 9-48hours
describe the symptoms of listeria monocytogenes?
- fever
- muscle aches
- diarrhoea
= pregnant women may have mild symptoms
how would one acquire listeria monocytogenes?
- unpasteurised milk products, deli counter
describe the invasiveness of listeria monocytogenes?
- 2-6weeks
- immunosuppressed
- aged > 50
- pregnant
- meningitis/bacteraemia
what type of bacteria is listeria monocytogenes?
gram + rod
how is listeria monocytogenes spread?
- food borne transmission
- mother to child
- rarely other
describe monocytosis in listeria monocytogenes?
- extract of cell membrane causes monocytosis in rabies, rarely in humans
- but 67% cases of listeria monocytogenes have neutrophils
what are 2 important viruses in viral gastroenteritis?
- rotavirus
- noravirus
describe rotavirus.
= most common cause in kids <3years
- all kids get it before 5
- person to person, faecal oral spread (direct & indirect)
- usually in winter
- moderate fever
- vomiting
- diarrhoea
- not bloody
- selt limiting
- lasts a week
describe the infectious dose of rotavirus?
= low infectious dose
- 100-1000particles
= faecal-oral
- survives in environment
- billions shed in faeces when diarrhoea
- affects absorption & secretion in bowel
what may children with rotavirus have?
= post infection malabsorptions
- leading to more diarrhoea
what is the key to managing rotavirus?
= hydration
describe the rotavirus vaccine?
- oral
- live attenuated
- excreted in faeces
- 2 doses = 2 and 3 months
describe norovirus?
= winter vomiting disease
- affects all ages (HIGHLY infectious)
= 5 billions viruses per gram of faeces - faecal-oral/droplet routes of spread
- person to person
- environmental survival on fomites for days-weeks
describe diagnosis and treatment of norovirus?
Diagnosis
= PCR on stool, takes 6hours
treatment
= self-limiting (unpleasant)
- hydration is key
describe diagnosis and treatment of norovirus?
Diagnosis
= PCR on stool, takes 6hours
treatment
= self-limiting (unpleasant)
- hydration is key
