- Most common cause of significant adult gastroenteritis world-wide is bacterial infection.
- Organisms to be discussed:
- S. enteritidis and S. typhimurium .
- Commensals in poultry and chicken.
- Transmitted via contaminated foodstuffs and water.
- Affects large and small bowel.
- Typical symptoms starts between 12–48 hours after infection.
- Spontaneous resolution usually occurs in 3–6 days.
- Young children and elderly at risk of significant dehydration.
- Treat with ciprofloxacin 500mg po bd reduced duration and severity of symptoms.
- Occur world-wide mainly in India and Africa.
- Typhoid by Salmonella typhi.
- Parathyphoid by S. paratyphi A, B or C.
- Incubation period is 10–14 days.
- Invades small bowel (peyer’s patches) to regional LN to blood.
- Scanty maculopapular rash (‘rose spots’).
- (Usually in 3 rd week of illness)
- After clinical recovery they become convalescent carriers.
- Usual site of carriage is the gall bladder
- Culture of S. typhi or S. paratyphi from the patient.
- Blood culture is positive in most cases in the first 2 weeks.
- Bone marrow culture is more sensitive than blood culture, but is rarely required.
- Ciprofloxacin 500 mg twice daily) are now the treatment of choice.
- Azithromycin if resistant.
- A common cause of childhood gastroenteritis in developing countries.
- Affects small and large bowel.
- Incubation period 2-4 days.
- Self limiting in 3-5 days.
- If severe treat with azithromycin 500mg po od.
- Causes classical bacillary dysentery .
- S. dysenteriae, S. flexneri and S. sonnei.
- Only small numbers needed to be ingested to cause illness (<200).
- Symptoms start 24–48 hours after ingestion
- Frequent small-volume stools containing blood and mucus.
- Self-limiting in 7–10 days.
- Resistance to antibiotics is widespread.
Entero haemorrhagic Escherichia coli (EHEC)
- Secretes a toxin ( Shiga-like toxin 1 ) which affects vascular endothelial cells in the gut and in the kidney.
- Incubation period of 12–48 hours.
- Patient may develop TTP or HUS .
- Avoid antibiotics as may precipitate HUS.
- Vibrio cholera-next slide.
- Vibrio parahaemolyticus causes acute watery diarrhoea after eating raw fish or shellfish that has been kept for several hours without refrigeration.
- Self limiting up to 10 days.
- Pure enterotoxigenic diarrhoea .
- Gram-negative bacillus, Vibrio cholerae .
- Common in Bangladesh, India and South East Asia.
- Transmission is by the faeco-oral route
- Proliferates in the small intestine .
- Releases exotoxin which produces massive secretion of isotonic fluid into the intestinal lumen.
- Releases serotonin (5-HT) from enterochromaffin cells in the gut, which activates a neural secretory reflex in the enteric nervous system.
- Incubation period few hours to 6 days.
- Majority have mild illness.
- profuse painless diarrhoea
- Children may present with convulsions owing to hypoglycaemia.
- Diagnosis is largely clinical.
- Demonstration of organism in stool not diagnostic .
- Stool and rectal swabs should be taken for culture to confirm the diagnosis.
- Mainstay of treatment is rehydration.
- Tetracycline or erythromycin x 3/7.
- Help to eradicate infection, decrease stool output, and shorten the duration of the illness.
- However, a single dose of ciprofloxacin or azithromycin (each 1 g) is a better choice.
- Prevention by good hygiene and improved sanitation.
- Human disease arise either via contaminated food products,ie: pork, or direct animal contact.
- Watery diarrhoea, dysentery and mesenteric adenitis.
- Self-limiting but ciprofloxacin may shorten the duration.
- Y. pseudotuberculosis causes mesenteric adenitis and terminal ileitis .
- Produce a heat-stable toxin ( enterotoxin B ) which causes massive secretion of fluid into the intestinal lumen.
- Onset of symptoms is rapid , often within 2–4 hours of consumption.
- Causes violent vomiting, followed within hours by profuse watery diarrhoea.
- Symptoms have usually subsided within 24 hours.
- One causes diarrhea the other causes severe vomiting.
- Clostridium difficile causes antibiotic-associated diarrhoea, colitis and pseudomembranous colitis.
- Gram-positive,anaerobic, spore-forming bacillus.
- Normal flora in 3-5% general population.
- Up to 20% in hospitalized patients.
- Almost all antibiotics have been implicated but the present increase has been attributed to the overuse of quinolones (e.g. ciprofloxacin ).
- Diarrhoea can begin anything from 2 days to a month after taking antibiotics.
- The colonic mucosa is inflamed and ulcerated and can be covered by an adherent membrane-like material (pseudomembranous colitis).
- Detecting A or B toxins in the stools by ELISA techniques.
- Discontinue causative antibiotic.
- Treat with metronidazole 400 mg po tds or
- Oral vancomycin 125 mg po QID.
- Isolation of patients with C. difficile.
- Clostridium perfringens infection is due to inadequately cooked food .
- Releases enterotoxin causing watery diarrhoea with severe abdominal pain, usually without vomiting.
- By which mechanism does vibrio cholera cause gastroenteritis?
- Name 3 organisms causing watery diarrhea and profuse vomiting.
- Clinical features of thyphoid fever.
- In thyphoid, when does complications develop?
- Common site for carriage of s.thyphi?
- What is the most common cause of childhood gastroenteritis in developing countries.
- A person had only eaten very small amount of food at a stall, becomes unwell with diarrhea. Passing frequent small-volume stools containing blood and mucus. Most likely organism?
- Consequence of infection from EHEC?
- Which toxin does EHEC secrete?
- A person becomes very unwell with profuse painless diarrhoea, ‘ rice water’ stool , vomiting and ended up in ICU with hypovolemic shock. Most likely organism?
- Which organism has the potential to cause mesenteric adenitis?
- A person becomes unwell with vomiting and diarrhea only after several hours of eating dinner. Most likely organism?
- A person eats fried rice takeaway and becomes sick afterwards. Most likely organism?
- A person took ciprofloxacin a month ago and now develops diarrhea. Most likely organism? Treatment choice?
- What is the most common organism in Traveller’s diarrhea?