Gastroentritis Study Guides

GAST ROENT RIT IS Epidemiology • • • Disease burden o >2 million paediatric deaths per year from gastroenteritis o 76 million cases of food poisoning per year ▪ 325000 hospitalizations & 5000 deaths per year o 34 million travellers to non-industrialized countries per year ▪ Up to 50% will experience diarrhoea ▪ Up to 10% will experience dysentery Predominantly oral-faecal transmission o Risk of gastroenteritis inversely correlates with sanitation Host risk factors o Age ▪ Very young & very old are most vulnerable ▪ Young adults at greater risk due to greater risk taking o Immune compromise e.g. HIV, malnutrition, cytotoxic drugs o Achlorhydria ▪ Loss of protective gastric acid (eg gastrectomy; drugs) o Recent antibiotics (within 4 weeks) Causes • • • Viruses – rotavirus, notavirus Bacteria o ETEC; Bacillus cereus; Staphylococcus aureus o Campylobacter species; Salmonella enterica Parasites o Giardia intestinalis; Entamoeba histolytica o Cryptosporidium parvum Diagnosis • • History o Type of diarrhoea – watery? Presence of blood/mucus? o Host factors – immune compromise? Recent antibiotics? o Risk factors – diet (incubation from suspect food), travel (destination, incubation from date of return), contacts (institution based, shared meals) Examination o Must assess fluid status, especially in children ▪ HR, BP, mucous membranes, skin turgor, neck veins etc. o Check for sepsis (enteric fever) o Inspect diarrhoea ▪ PR exam for blood/mucous (unless neutropaenic) o Abdominal examination for complications • • • • • Stool microscopy o Request OCP if parasites suspected o WCC and RBC suggest inflammatory cause Stool culture/PCR o Request culture for Yersinia or Vibrio if suspected Copra-antigens o Clostridium difficile toxin, rotavirus, adenovirus, Giardia, Cryptosporidium etc. Blood cultures (enteric fever) Radiology (complications) Treatment • • • • • • Supportive o If possible eliminate any reversible predisposing factors o Fluid & electrolyte replacement is the mainstay of therapy ▪ If unable to maintain oral intake (vomiting), hospital admission & IV fluids ▪ Oral re-hydration solutions (Gastrolyte, Hydralyte, etc) ▪ Avoid making an oral re-hydration solution (error prone) ▪ Avoid caffeine (including soft drinks eg Coca Cola) since pro- secretory Symptomatic o Avoid dairy foods and fatty foods short term o Anti-motility agents (eg loperamide, codeine, etc) ▪ Avoid in dysentery and inflammatory diarrhoea ▪ Risk of ileus, toxic megacolon & perforation ▪ Restrict to mild, non-inflammatory diarrhoea for short term symptom control ▪ Never use in children Antibiotics are generally not indicated o Gastroenteritis usually resolves without antibiotics o Antibiotics do not benefit viral gastroenteritis (most cases) o Can cause diarrhoea (pro-motility, Clostridium difficile) – Contra-indicated in EHEC due to risk of HUS o Prolongs carriage of Salmonella if this is the cause Consider antibiotics only in invasive disease (enteric fever), non-resolving gastroenteritis (diarrhoea >2 weeks), shigellosis (because highly contagious) or pseudomembranous colitis Usual antibiotics o Campylobacter species: azithromycin 500mg daily po; ciprofloxacin 500mg bd po o Enteric fever: azithromycin 1g daily po/IV; ciprofloxacin 500-750mg bd po; ceftriaxone 2g daily IV o Shigella species: ciprofloxacin 500mg bd po; co-trimoxasole 160/800mg bd po o Clostridium difficile: metronidazole 400mg tds po; vancomycin 125mg qid po o Traveler’s diarrhoea (ETEC): azithromycin 1g stat po; followed prn by azithromycin 500mg daily po or ciprofloxacin 500mg bd po for up to 3 days Other o Probiotics – evidence is variable (beneficial from no effect to harmful), may shorten symptom duration o Zinc supplementation in paediatric patients ▪ WHO recommendation & Cochrane review (2008) ▪ 10-20mg of a zinc salt (sulfate, acetate or gluconate) daily po ▪ ▪ ▪ ▪ Prevention • • • • • Reduces duration of symptoms Reduces likelihood of subsequent gastroenteritis (2-3 months) No proven benefit if age <6 months Not proven to reduce mortality or hospitalisation rate Behaviour modification o Hand washing o Cleaning before food preparation o Avoid raw, un-cooked or under-cooked foods o Peel fruit o Boil water (>1 minute; >3 minutes at altitude) o Bottled/canned drinks (check seals) o Avoid ice in drinks Vaccination o Rotavirus vaccine for children o Consider oral cholera vaccine if traveling to area endemic for Vibrio cholera o Consider Salmonella serovar Typhi vaccine if traveling to area endemic for typhoid (does not protect against paratyphoid or non-Typhi serovars of Salmonella) Pro-biotics o Usually Lactobacillus containing o Theory is to prevent colonisation or proliferation of pathogenic bacteria (eg ETEC during travel; Clostridium difficile on antibiotics) o Some small studies show benefit in prophylaxis or reduced severity (shorter symptom duration) but results are inconsistent o Await further evidence Prophylactic antibiotics o Case for giving prophylactic antibiotics is even weaker than the case for giving therapeutic antibiotics o No evidence for benefit except in traveler’s diarrhoea but numerous reasons not to use ▪ Self-limiting infection; does not prevent viral gastroenteritis; prohibitive expense to give to all travelers; promotes antibiotic resistance; risks unnecessary side effects o Consider in vulnerable persons (eg immune compromised; type 1 DM; IBM; heart/kidney failure) for travel <3 weeks ▪ norfloxacin 400mg daily po; ciprofloxacin 500mg daily po Infection Control & Public Health o Public sanitation (treated sewage separate from a clean water supply) o Surveillance ▪ Outbreak notification to Public Health ▪ Laboratory notification of gastrointestinal pathogens to Public Health o In hospitals, single rooms with dedicated toilets; PPE; hand-washing