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Gastroenteritis

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Gastroentritis its causes, symptoms and control.

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Gastroenteritis

  1. 1. GASTROENTERITIS
  2. 2. Gastroenteritis • Inflammation of stomach or intestines – Inhibits nutrient absorption and excessive H2O and electrolyte loss • Bacterial • Viral • Parasites • Poisoning by microbial toxins – food borne intoxication
  3. 3. • Signs and Symptoms: – General features: diarrhea, loss of appetite, abdominal cramps, nausea, vomiting and possibly fever – Dysentery – Typically self Limiting • Enteric fevers – Systemic with severe headache, high fever, abscesses, intestinal rupture, shock and death
  4. 4. • Epidemiology – Occurs worldwide – Oral to fecal route of transmission • Water common reservoir • Overcrowding & poor sanitation are risk factors • Animals may be source of infection
  5. 5. • Prevention – Hand washing – Proper food handling and complete cooking – Pasteurization of milk and juices – Adequate sanitation – Safe water supplies • Treatment – Rapid replacement of fluids and electrolytes – Anti-nausea medication – Antimicrobials may be used in severe cases
  6. 6. Bacterial Gastroenteritis • 3 groups of gram negative bacteria account for most bacterial intestinal infections: – Vibrio cholerae (Cholera) – Enterics (Salmonella, Shigella, E. coli) – Campylobacter jejuni
  7. 7. Cholera • Causative agent: Vibrio cholerae • High infectious dose – Bacteria sensitive to stomach acid – Adheres to small intestine and multiply – Bacteria don’t enter cells
  8. 8. • Cholera toxin – Potent exotoxin – Causes intestinal cells to rapidly pump out electrolytes – Passive osmotic H2O loss follows – Metabolic acidosis – Shock
  9. 9. • Heavy loss of fluid – “rice-water stool” • Up to 20L of fluids lost per day • May discharge 1 million bacteria per ml of feces • Untreated cases potentially fatal – Fluid/electrolyte replacement – Tetracycline reduces toxin production
  10. 10. Shigellosis • Causative Agent: Shigella sp. – S. dysenteriae, S. flexneri, S. boydii, S. sonnei • Low infecting dose – Bacteria not sensitive to stomach acid – Characterized by fever and dysentery
  11. 11. •Infects cells of large intestine and initiates intense inflammatory response •Dead cells slough off •Produces areas covered with pus and blood
  12. 12. • All species produce enterotoxin and type III secretion systems • S. dysenteriae produces powerful endotoxin – shiga-toxin • Ciprofloxacin, rifampin or azithromycin may reduce duration and infectivity
  13. 13. Traveler’s Diarrhea • Causative Agent: Escherichia coli – Multiple antigenic strains (O, H, K) – Virulent strains have fimbriae, adhesions and multiple toxins • Enterotoxigenic E. coli – Enterotoxins – Type III secretion system – Typically self limiting
  14. 14. • Enterohemorrhagic E. coli – O157:H7 – Produce potent Shiga-like toxins and type III secretion systems • Antimicrobials cause increase in toxin production
  15. 15. Salmonellosis and Typhoid Fever • Causative agent: Salmonella enterica – 2000 strains (serotypes) – Typhimurium and Enteritidis commonly cause Salmonellosis – Typhi and Paratyphi cause Typhoid Fever
  16. 16. • Common intestinal flora of many animals • Contaminated animal products are reservoir • Reptiles, eggs and undercooked poultry
  17. 17. •Virulent strains tolerate stomach acid and pass to intestines •Toxin induces phagocytosis in intestinal cells •Pathogen reproduces inside phagosome killing host cell •Bacteria (Typhi) may pass倠䁝 through intestinal cells into bloodstream
  18. 18. Campylobacteriosis • Causative agent: Campylobacter jejuni – Leading cause of bacterial diarrhea in United States – Estimated 1million cases annually with ~100 deaths • Associated with poultry – Low infecting dose
  19. 19. • Virulent strains possess adhesions, cytotoxins and endotoxin – Induce endocytosis in cells of intestine and initiate inflammation and bleeding lesions • Non-motile mutants are avirulent • Severe cases treated with ciprofloxacin or azithromycin
  20. 20. Bacterial Food Intoxication • Staphylococcus aureus – Halotolerent; grows well in foods at room temp – Associated with cafeterias and social functions
  21. 21. • 5 heat stable enterotoxins: – 1000 for up to 30 min – Stimulate muscle contractions, nausea and intense vomiting, diarrhea and cramping – Acute and self limiting • symptoms begin 4-6 hrs after consumption and end within 24 hrs
  22. 22. Botulism • Causative agent: – Clostridium botulinum • Obligate anaerobic, Gram +, spore forming bacillus – Produce 7 different neurotoxins • One of most deadly toxins known
  23. 23. • Signs & Symptoms – Dizziness, dry mouth, blurred vision – Abdominal symptoms include pain, nausea, vomiting and diarrhea or constipation – Progressive paralysis • Paralysis of respiratory muscles most common cause of death
  24. 24. • 3 forms of botulism: – Food-borne botulism – progressive paralysis of all voluntary muscles due to toxin production – Wound botulism – similar symptoms – Infant botulism – bacteria grow in the intestines, producing non-specific symptoms • “floppy baby syndrome”

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