gastroenteritis Flashcards
definition of gastroenteritis
acute inflammation of lining of the GI tract due to enteric infection
manifested by nausea, vomiting, diarrhoea and abdominal discomfort
types of aetiology of gastroenteritis
virus
bacteria
protazoa
toxins contained in contaminated food or water
viruses causing gastroenteritis
- rotavirus
- adenovirus
- astrovirus
- clacvirus
- norwalk virus
- small round structured virus
- norovirus
- sapovirus
- cmv
bacteria causing gastroenteritis
- campylobacter jejuni
- E coli - particularly 0157
- salmonella
- shigella
- vibro cholerae
- listeria
- yersinia enterocolitica
- staph aureus
- clostridium perfringes
- yersinia entercolitica
- bacillus cereus
protazoal causes of gastroenteritis
entamoeba histolytica
cryptosporidium parvum
giardia lamblia
cyclospora cayetanensis
trichinella
trichuriasis
intestinal flukes
toxins that cause gastroenteritis
from staphylococcus aureus, clostridium botulinum, clostridium perfringens, bacillus cereus, mushrooms, heavy metals, seafood
commonly contaminated food causing gastroenteritis
improperly cooked meat - s aureus, c perfringens
old rice - B cereus, S aureus
eggs and poultry - salmonella
milk and cheese - campylobacter, listeria
canned food - botulinism
non-inflammatory mechanisms of gastroenteritis
V cholerae, enterotoxigenic e coli
produce enterotoxins that cause enterocytes to secrete water and electrolytes
inflammatory mechanism of gastroenteritis
shigella, enteroinvasive E coli
release cytotoxins and invade and damage epithelium
with greater invasion and bacteraemia in the case of salmonella typhi
epidemiology of gastroenteritis
common
under reported
serious cause of morbidity and mortality in the developing world
sx of gastroenteritis
sudden onset nausea, vomiting and anorexia
diarrhoea - bloody or watery
abdo pain/dyscomfort
fever and malaise
enquire about recent travel, AB use and recent food intake - how cooked, source and whether anyone else is ill
time of onset - toxins = early ie 1-24hr. Bacterial/viral/protazoal 12hr or later
effect of toxin:
- botulinism = paralysis
- mushrooms = fits, renal or liver failure
signs of gastroenteritis
diffuse abod tenderness
abdo distension
increased bowel sounds
if severe - pyrexia, dehydration, hypotension and peripheral shut down
investigations for gastroenteritis
- blood
- FBC
- blood culture - help identify bacteraemia
- UE - dehydration
- stool
- faecal microscopy for polymorphs, parasites, oocusts, culture, electron microscopy (used to dx viral infections)
- analysis for toxins, particularly for pseudomembranous colitis (C diff toxin)
- AXR or US
- exclude other causes of abdo pain
- sigmoidoscopy
- often unnecessary unless IBD needs to be excluded
management of gastroenteritis
bed rest, fluid and electrolyte replacement with oral rehydration soln (containing glucose and salt)
IV rehydration in severe vomiting
most infections are self limiting
AB treatment only needed if severe or the infective agent has been identified eg cuprofloxacin against salmonella, shigella, campylobacter
thyphoid fever management
boulinism - botulinum antitoxin IM and manage in ITU
public health - often a notifyable disease, educate on basic hygeine and cooking
complications of gastroenteritis
dehydration
electrolyte imbalance
prerenal failure
secondary lactose intolerance - particualry in infants
sepsis and shock - particularly salmonella and shigella
haemolytic uraemic syndrome - associated with toxins from E coli 0157
Guillian-Barre syndrome may occur weeks after recovery from campylobacter gastroenteritis
botulinism - resp muscle weakness or paralysis
prognosis of gastroenteritis
generally good
majority of conditions are self limiting
different definitions of diarrhoea
acute diarrhoea >= episodes partially formed or watery stool/day <14days
dystentry - infectious gastroenteritis with bloody diarrhoea
persistent diarrhoea - acutely starting diarrhoea lasting >14d
traveller’s diarrhoea - starting during or shortly after foreign travel
food poisening - disease (infection/toxin) caysed by consumption of food/water - notifyable disease
causative organisms of diarrhoea w/o blood ie enteritis
norovirus
rotavirus
astrpovirus
enteric adenovirus
enterotoxigenic E coli
enteropathogenic E coli
toxin producing staph aureus
cholera
clostridium perfringens
giardia
cyrptosporidium
cyclospora cayetaenensis
causative organisms of diarrhoea with blood ie dysentry
shigellosis - bacillary dysentery
enterohaemorrhagic E colu
campylobacter enterocolitis
c diff
yersinia enterocolitis
entamoebic histolytica (amoebic dysentery)
trichuriasis (whipworm0
CMV
summarise traveller’s diarrhoea
affectes 20-60% travellers
high risk areas: south asia, central and south america, africa
major cause - enterotoxigenic E coli
prevention - boil water, cook thoroughly, peel fruit and veg. Avoid ice, salads adn shellfish. Drink with a straw. Hand wash with soap
Sx - during 1st week of travel
- enterotoxigenic E coli = watery diarrhoea, preceded by cramps and nausea
- giardia lamblia = upper GI symptoms eg bloating, belching
- campylobacter jejuni and shigella = colitic symptoms, urgency, cramps
Rx
- oral rehydration - clear fluid or oral rehydration salts
- antimobility ageents eg loperamide, bismuth subsalicyclates - avoid if severe pain or bloody diarrhoea as may indicate invasive colitis
- AB - not usually indicated - considered if rapid cessation of diarrhoea needed and/or limited access to sanitation or healthcare
AB prophylaxis
- not recommended - severe disease is rare and risk of c diff
- consider in immunosuppressed, GI pathology or increased risk of dehydration (sickle, CKD)
persistant diarrhoea
- investigate if >14d or dysentry
- FBC, UE, LFT, CRP, ESR, stool microscopy for ova, cysts, parasites
- molecular testing for pre-defined microbes
- ddx of persistant diarrhoea = giardia, entamoeba histolytica, shigella
- post infectious OBS is a dx of exclusion
summarise norovirus
sigle stranded RNA virus
highly infectious
transmission - contact with infected people, env, food (approx 10%)
most common cause of infectious GI disease (approx 600000 cases in eng/yr)
Sx - 12-48hr after exposure, lasting 24-72hr. Acute vom, watery diarrhoea, cramps, nausea
virus shed in stool even if asymptomatic
numerous genotypes and unknown longevity of immunity therefore repeat infection happens
Ix - clinical, stool sample reverse transcriptase PCR
Rx - supportive, anti-motility agents, usually self limiting
summarise rotavirus
double strand RNA virus
wheel like appearance on EM
commonest cause of gastroenteritis in children
Sx - incubation 2d, watery diarrhoea and vom for 3-8d, fever, abdo pain
Ix - clinical, ag in stool
Rx - supportive
routine vaccine in UK
virus shed in stool post vaccine = careful hygiene if immunocomprimised and changing nappies
live vaccine therefore delay vaccination if in utero biologic agents with active transfer across the placenta eg infliximab, adalimumab
enterotoxigenic E coli
gram -ve anaerobe
disease due to heat stable or heat-labile toxin which stimulates NaVL na dwater efflux into gut lumen
20% of all infective diarrhoea, 80% of traveller’s diarrhoea
sx - incubation of 1-3d, watery diarrhoea, cramps, lasts 3-4d
dx - clinical, stool culture to identify toxin
Rx - supportive
clostridium perfringes (type A)
gram +ve anaerobe
produces enterotoxin
spores survive cookung and germinate during unrefriginated storage
2-30 outbreaks/yr in the UK
Sx - sudden onset diarrhoea, cramps, <24hr
Ix - stool toxin, quantification of faecal bacteria
Rx - supportive
B toxin of C perfringens type C can cause necrotozing enteritis with fuliment disease, pain, bloody diarrhoea, septic shock
B toxin is sensitive to trypsin proteolysis so increased risk with trypsin inhibition by sweet potatoes, ascaris infection therefore occurs in New Guinae (pigbel), central/south america, south east asia, china
cholera
gram -ve, aerobic comma shaped flagellated motile vibrating/swarming rod
found in faecally contaminated water
serovars 01 and 0139 cause disease
approx 190000 cases in 2014
sx - incubation 2h-5d, approx 75% asymptomatic but shed bacteria, profuse (1L/hr) diarrhoea (rice-water stool), vomiting, dehydration, metabolic acidosis, circulatory collapse, death
dx - clinical - death due to watery diarrhoea = dehydration age >5 or any watery diarrhoea >5 during known epidemic. Identification of serovars 01 or 0139 in stool. Rapid dipstick testing available but culture confirmation is recommended
Rx - oral rehydration salts, safe water, adults might need 1L/hr initially - offer 100ml/5min. NG if vom. IV fluids if severly dehydrated: Ringer’s lactate or 0.9% saline plus ORS (beware low K+) up to 200mL/kg in first 24h. Antibiotics in severe dehydration to reduce diarrhoea - doxicycline or tetracycline
zinc shortens illness in children
prevention - clean water, oral cholera vaccines
shigella (sonnei, flexneri, dysenteriae, boydii)
gram -ve anaerobe
sx - wateryu or bloody diarrhoea, pain, tenesmus, fever 1-2days after exposure
lasts 5-7days - more in MSM
complications - bacteraemia, reactive arthritis, HUS
dx - stool culture, PCR.enzyme immunoassay
Rx - supportive. Green bananas (more short chain fatty acids in colon), zinc if <6yrs, vit A. AB if systemically unwell/immunocomp
avoid anti-diarrhoeal - risk of toxic dilatation
enterohaemorrhagic/shiga-toxin producing E coli (STEC) eg O157:H7
gram -ve anaerobe
produces veratoxins which are shiga like due to similarity with shigella dysentriae
sx - incubation 3-8d, diarrhoea, haemorrhagic colitis. HUS in up to 10%
Dx - stool culture. PCR/enzyme immunoassay for Shiga-toxin
Rx - supportive. NO AB - increase risk of HUS
campylobacter
gram -ve spiral shaped rod
Sx - incubation 1-10d (usually 2-5d). bloody diarrhoea, pain, fever, headache
complications - bacteraemia, hepatitis, pancreatitis, miscarriage, reactive arthritis, Guillain-Barre
dx - stool culture/ PCR/enzyme immunoassay
Rx - supportive, AB only in invasive cases
salmonella enterocolitis (non-typhoidal)
gram -ve, anaerobic motile bacilli
presentation - diarrhoea, cramps, fever, usually with 12-36hr of exposure
invasive infection (<10%) can cause bacteraemia/sepsis, meningitis osteomyelitis, septic arthritis
Dx - stool culture, PCR
Rx - supportive
consider AB in sever/extra-intestinal disease according to local sensitivities
yersinia enterocolitica
gram -ve rod
presentation - incubation 4-7d. Diarrhoea, fever, pain (may mimic appendicitis) vomiting. May last 1-3wk. erythema dodosum, reactive arthritis
dx - stool culture, agglutination titres
Rx - AB in severe disease
giardiasis
giardia lamblia is a flagellate protozoan
faecal-oral spread from infected drinking water/food/fomites
Sx - asymptomatic, incubation 1-3wk, diarrhoea, flatulance, bloating, pain, malabsorption. lasts 2-6wk. Most common dx if persistent traveller’s diarrhoea
dx - stool microscopy for cysts and trophozoites. Intermittent shedding so multiple samples (>3) may increase sensitivity. faecal immunoassay. PCR for dx/subtype. duodenal fluid aspirate analysis
rx - hygiene to prevent transmission. Metronidazole (treatment failure in up to 20%), tinidazole (single dose), albendazole (less SE, simultaneous treatment of other parasites)
lactulose intolerance develops in 20-40%
cryptosporidium
apicomplexan protozoan
ingestion of oocytes in infected water
asymptomatic or self-limiting diarrhoea in immunocompetent hosts
chronic/severe diarrhoea with immunosuppression - HIV, transplantation, hypogammaglobulinaemia, immunosuppressive therapy
amaebiasis
protazoan entamoeba haemolutica
10% worlds population, mortality 100000/yr
faecal oral spread
boil water to destroy cysts
sx:
- asymptomatic passaghe of cysts in 90% - luminal amoebiasis
- intestinal amoebiasis - dysentery (often insidious onset/relapsing), pain, colitis, appendicitis, toxic megacolon. Amoeboma - inflammatory abdominal mass, usually caecal/RIF +- obstruction
- extra-intestinal (invasive) disease - amoebic liver abscess in 1%. single mass containing anchovy-sauce pus. High swinging fever, RUQ pain/tenderness. LFT normal or high - cholestatic. 50% have no history of amoebic dysentry. Also peritonitis (rupture of colonic abscess), pleuropulmonary abscess cutaneous/genital lesions
dx
- microscopy of stool (cysts and trophozoites), aspirate or biopsy
- enzyme immunoassay - ag detection as adjunct to microscopy, Ab detection in extra-intestinal disease
- PCR can distinguish E histolytica from morphologically identical but non-invasive E dispar
Rx
- metronidazole/tinidazole for amoebic dysentry and invasive disease
- diloxanide furoate - luminal agent 10d course to destroy gut cysts, given in asymptomatic gut carriers adn symptomatic disease, in addition to other treatment.
- abscess may require (image guided) drainage
cyclospora
coccidean protazoan - cyclospora cayetanesis
approx 50 imported cases a yr
sx - flu like prodrome, watery diarrhoea, weight loss, marked fatigue, low grade fever in 35%. self limiting in 7-9wks
dx - autoflurescent oocytes in stool - appear blue-green under UV flurescence. PCR
treatment - co-trimoxazole
nematodes
roundworm - ascaris lumbricoides approx 1 billion affected. Tricinella spiralis - contaminated meat source
whipworm - truchuris trichiura, 600-800 million affected
hookworm - nector americanus, ancyclostoma duodenale approx 700 million affected
threadworm - strongloides stercoralis, 30-100million affected
one of the most common infections in the world - affects the poor and deprived
parasites live in intestines, producing 1000s of egg/day in faeces
humans infected by eggs (ascariasis, trichinosis) or larvae (ancylostoma) in contaminated food or via direct penetration of the skin - kookworm, strongyloides
sx - diarrhoea, abdo pain, blood/protein loss, impaired growth/cognitive development. pruritis/urticaria if migration involves skin (strongyloides). Lung invasion (ascarias, hookworm, strongyloides) –> loeffler-like syndrome (cough, SOB, wheeze, haemoptysis, consolidation, eosinophilia). other tissue invasion (trichinosis) - myalgia, conjunctivitis, photophobia, meningitis, encephalitis, neuropathy
dx - clinical, eggs in stool, eosinophilia
rx - anthelmintic drugs
taeniasis (tapeworm)
includes taenia solim (pork, 2-8m, 50000 eggs/worm) taemia saginata (beef 4-12m, 100000 eggs/worm), taemia asiatica (asian, 4-8m, millions of eggs)
sx - no or mild GI symptoms, tapeworm segments through anus/in faeces
dx - eggs/proglottids in faeces
rx - praxiquantel, niclosamide
thyphoid fever mx
Third-generation cephalosporins.
or quinolones and chloramphenicol.
Notifiable disease
summarise C difficile
gram +ve anaerobic bacillus
most common healthcare associated pathogen
part of flora in some people
coverts to vegetative (growth) state - production of enterotoxins A and B = colitis
happens when inhibition by competing flora is lost because of AB - consider in all diarrhoea with AB esp if neutrophilia
watery diarrhoea, mild -> fulminant colitis
ileus, toxic megacolon
ix - immunoassay for glutamate dehudrogenase (common ag), detection of toxin (toxin immunoassay, toxic gene nucleic acid amplification - distinguish infection from carrier
mx of c diff
SIGHT
- suspect
- isolate with 2hr
- gloves and aprons
- hand wash with soap
- test immediately
mild - metronidazole
severe (WCC >15x10(9)/L or AKI, or colitis, or >38.5 degrees) - vancomycin of fidaxomicin
non-responders - high dose vancomycin + IV metronidazole, fidaxomicin, IV immunoglobulin
recurrence - weaning vancomycin, fidaxomicin, faecal transplantation
staphylococcus aureus
coagulase +ve
toxin release = disease distant from infection - preformed toxin in food = sudden D and V
dx - +ve culture from relevant site
Mx - sepsis management, supportive
clues from Hx of pathogens causing gastroenteritis
C. Diff: Use of antibiotics, antiperistaltic drugs
Staph aureus: food, 1-6 hours after eating, short lived
Vibrio cholera: rice water diarrhoea, poor sanitation, shock
E. Coli: leafy vegetables
Bacillus cereus: reheated rice, can cause cerebral abscess
Salmonella: eggs, poultry may present with constipation, multiplies in Payer’s patches of the intestine
Campylobacter: uncooked poultry
Haemorrhagic E.coli: leafy vegetables - Bloody diarrhoea followed by haemolytic uraemic syndrome
Entamobea histolytica: poor sanitation, tropical places, MSM
Shigella: person-to-person contact, poor sanitation, MSM
Salmonella: eggs
