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Gastroenteritis

Gastroenteritis. Inflammation of stomach or intestines Inhibits nutrient absorption and excessive H 2 O and electrolyte loss Bacterial Viral Parasites Poisoning by microbial toxins food borne intoxication. Signs and Symptoms :

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Gastroenteritis

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  1. 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

  2. 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

  3. Epidemiology • Occurs worldwide • Oral to fecal route of transmission • Water common reservoir • Overcrowding & poor sanitation are risk factors • Animals may be source of infection

  4. 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

  5. BacterialGastroenteritis • 3 groups of gram negative bacteria account for most bacterial intestinal infections: • Vibrio cholerae (Cholera) • Enterics (Salmonella, Shigella, E. coli) • Campylobacter jejuni

  6. Cholera • Causative agent: Vibrio cholerae • High infectious dose • Bacteria sensitive to stomach acid • Adheres to small intestine and multiply • Bacteria don’t enter cells

  7. Cholera toxin • Potent exotoxin • Causes intestinal cells to rapidly pump out electrolytes • Passive osmotic H2O loss follows • Metabolic acidosis • Shock

  8. 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

  9. 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

  10. Infects cells of large intestine and • initiates intense inflammatory • response • Dead cells slough off • Produces areas covered with pus and blood

  11. 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

  12. 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

  13. Enterohemorrhagic E. coli • O157:H7 • Produce potent Shiga-like toxins and type III secretion systems • Antimicrobials cause increase in toxin production

  14. Salmonellosis and Typhoid Fever • Causative agent: Salmonella enterica • 2000 strains (serotypes) • Typhimurium and Enteritidis commonly cause Salmonellosis • Typhi and Paratyphicause Typhoid Fever

  15. Common intestinal flora of many animals • Contaminated animal products are reservoir • Reptiles, eggs and undercooked poultry

  16. 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 • through intestinal cells into • bloodstream

  17. Typhoid fever is an enteric fever • Macrophages carry bacteria to liver, spleen, bone marrow and gallbladder • Treated with ciprofloxacin or ampicillin • Surgical removal of gallbladder

  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. 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. Guillain-Barré Syndrome • Tingling of the feet leads to progressive paralysis of the legs, arms and rest of the body • 40% of cases preceded by campylobacteriosis • May be associated with autoimmune response • 80% recover completely; 5% mortality with treatment

  21. Viral Gastroenteritis • Common causative agents: • Rotaviruses and Noroviruses • Both naked RNA viruses Star-like Noroviruses Wheel -like Rotaviruses

  22. Epidemology • Infect intestinal cells causing cell death • Typically self-limiting • Norovirus epidemics cause 90% of cases • Rotaviruses responsible for 50% infant cases of serious diarrhea • 600,000 worldwide annual fatalities • Oral vaccine available

  23. Bacterial Food Intoxication • Staphylococcus aureus • Halotolerent; grows well in foods at room temp • Associated with cafeterias and social functions

  24. 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

  25. Botulism • Causative agent: • Clostridium botulinum • Obligate anaerobic, Gram +, spore forming bacillus • Produce 7 different neurotoxins • One of most deadly toxins known

  26. 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

  27. 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”

  28. Epidemiology • Food borne botulism • Commercial sterilization • Toxin destroyed by heating foods • Wound botulism • deep crushing wounds • Infant botulism • Inhalation or ingestion of spores • Commonly associated with honey or juices

  29. Prevention • Proper sterilization and sealing of canned food • No honey or unpasteurized juices for infants!! • Treatment • Antitoxin • Gastric washing and surgical removal of tissues • Artificial respiration may be required • Anti-microbials given to kill bacteria in infant and wound botulism

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