Gastroenteritis
<ul><li>Most common cause of significant adult gastroenteritis world-wide is bacterial infection. </li></ul><ul><li>Organi...
Mechanisms
 
Salmonella <ul><li>S. enteritidis and S. typhimurium .  </li></ul><ul><li>Commensals in poultry and chicken. </li></ul><ul...
Enteric Fever <ul><li>Occur world-wide mainly in  India and Africa. </li></ul><ul><li>Typhoid by Salmonella typhi. </li></...
Clinical features <ul><li>Invades small bowel (peyer’s patches) to regional LN to blood. </li></ul><ul><li>In early stages...
Complications <ul><li>(Usually in 3 rd  week of illness) </li></ul><ul><li>meningitis </li></ul><ul><li>lobar pneumonia </...
Diagnosis <ul><li>Culture of S. typhi or S. paratyphi from the patient.  </li></ul><ul><li>Blood culture is positive in mo...
Management <ul><li>Ciprofloxacin 500 mg twice daily) are now the treatment of choice. </li></ul><ul><li>Azithromycin if re...
Campylobacter jejuni <ul><li>A common cause of  childhood gastroenteritis  in developing countries. </li></ul><ul><li>Affe...
Shigella <ul><li>Causes  classical bacillary dysentery . </li></ul><ul><li>S. dysenteriae, S. flexneri and S. sonnei. </li...
Entero haemorrhagic   Escherichia coli  (EHEC) <ul><li>Also known as VTEC. </li></ul><ul><li>Secretes a toxin ( Shiga-like...
Vibrio <ul><li>Vibrio cholera-next slide. </li></ul><ul><li>Vibrio  parahaemolyticus  causes acute watery diarrhoea after ...
Cholera <ul><li>Pure enterotoxigenic diarrhoea . </li></ul><ul><li>Gram-negative bacillus,  Vibrio cholerae . </li></ul><u...
<ul><li>Incubation period few hours to 6 days. </li></ul><ul><li>Majority have mild illness. </li></ul><ul><li>In severe c...
Treatment <ul><li>Mainstay of treatment is rehydration. </li></ul><ul><li>Tetracycline or erythromycin x 3/7. </li></ul><u...
Yersinia <ul><li>Yersinia enterocolitica. </li></ul><ul><li>Human disease arise either via contaminated food products,ie: ...
Staphylococcus aureus <ul><li>Produce a heat-stable toxin ( enterotoxin B ) which causes massive secretion of fluid into t...
Bacillus cereus <ul><li>Produces two toxins. </li></ul><ul><li>One causes diarrhea the other causes severe vomiting. </li>...
Clostridial infections <ul><li>Clostridium difficile  causes  antibiotic-associated  diarrhoea, colitis and pseudomembrano...
Clinical features <ul><li>Diarrhoea can begin anything from 2 days to a month after taking antibiotics. </li></ul><ul><li>...
Diagnosis <ul><li>Detecting A or B toxins in the stools by ELISA techniques. </li></ul>
Treatment <ul><li>Discontinue causative antibiotic. </li></ul><ul><li>Treat with  metronidazole  400 mg po tds or  </li></...
<ul><li>Clostridium perfringens  infection is due to  inadequately cooked food . </li></ul><ul><li>Releases enterotoxin ca...
Travellers Diarrhea
 
 
Possible questions <ul><li>By which mechanism does vibrio cholera cause gastroenteritis? </li></ul><ul><li>Name 3 organism...
<ul><li>What is the most common cause of childhood gastroenteritis in developing countries. </li></ul><ul><li>A person had...
<ul><li>A person becomes very unwell with  profuse painless diarrhoea,  ‘ rice water’ stool ,  vomiting and ended up in IC...
<ul><li>A person took ciprofloxacin a month ago and now develops diarrhea. Most likely organism? Treatment choice? </li></...
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Gastroenteritis

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Gastroenteritis

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