1. © 2004 Wadsworth – Thomson Learning Chapter 23 Infections of the Digestive System

2. © 2004 Wadsworth – Thomson Learning The Digestive System Figure 23.1

3. © 2004 Wadsworth – Thomson Learning Dental diseases Caries –S. mutans produces glucan –mesh for dental plaque lactic acid –damages enamel Periodontal disease –gingivitis inflammation of gums –periodontitis damage to tissue Bacteriodes gingivalis, B. intermedius Figure 23.2

4. © 2004 Wadsworth – Thomson Learning Mumps Mumps virus –inflammation-salivary gland/other organs bilateral parotitis –pathogenesis: incubation up to 18 days upper respiratory tract move into salivary glands –complications--spread to other areas orchitis (testes) deafness –vaccine (MMR)

5. © 2004 Wadsworth – Thomson Learning Shigellosis Shigella species bacillary dysentery Pathogenesis –penetrate mucosa cells--phagocytosis –produce toxin--Shiga toxin intense inflammation –bleeding/ulceration mucous and blood in excreta –normally self-limiting recovery in 2-7 days –severe dehydration--shock/death in children Figure 23.5

6. © 2004 Wadsworth – Thomson Learning Typhoid Fever Salmonella typhi Pathogenesis –contaminated food or water –infections at other sites –low infectious dose –involve lymphatic and circulatory systems Symptoms –about a month –severe fever/headache –apathy, weakness, abdominal pain and rash Figure 23.6

7. © 2004 Wadsworth – Thomson Learning Salmonellosis Salmonella species –pili adhere to GI tract –invasive growth epidemiology –ingestion of contaminated food –poultry/eggs/meats/other foods –inadequate cooking –improper thawing symptoms –abdominal pain, fever, diarrhea, last 3-5 days –complications in old, young, immunosuppressed Figure 23.8

8. © 2004 Wadsworth – Thomson Learning Escherichia coli Many strains nonpathogenic Enteroinvasive strains –Diarrhea in all ages Enteropathogenic strains –diarrhea in infants Enteroaggregative strains –Chronic diarrhea in infants Enterotoxigenic strains –Traveler’s diarrhea Enterohemorrhagic strains –E. coli O157:H7 –hemolytic uremic syndrome bloody diarrhea severe anemia kidney failure –shigalike toxin

9. © 2004 Wadsworth – Thomson Learning Cholera Vibrio cholerae –Asia, S. America, Africa Pathogenesis –multiply within small intestines –enterotoxin produce symptoms production of cyclic AMP in mucosal cells –secretion of water/electrolytes into lumen –loss of liters in hours sudden nausea, vomiting, abdominal pain, diarrhea rice-water stools severe dehydration –need IV to replace fluids –oral rehydration therapy Figure 23.9

10. © 2004 Wadsworth – Thomson Learning Gastrointestinal infections Vibrio parahaemolyticus Gastroenteritis –self-limited diarrhea or cholera-like illness –fish from contaminated waters Yersinia enterocolitica Enterocolitis –acute abdominal pain –resemble appendicitis cause of unnecessary appendectomy

11. © 2004 Wadsworth – Thomson Learning Gastrointestinal infections Campylobacter spp. –Campylobacteriosis –Bloody diarrhea –abdominal pain –fever Clostridium difficile –result of antibiotic therapy –usually resolves when therapy ends –cause of nosocomial infection

12. © 2004 Wadsworth – Thomson Learning Peptic Ulcer Disease Helicobacter pylori –gastric and duodenal ulcers growth in stomach damage to mucosal lining--specific products –survival in low pH organism produces urease –urea-->ammonia –increases pH in microenvironment –allows growth –Treatment antibiotics

13. © 2004 Wadsworth – Thomson Learning Staphylococcal food poisoning S. aureus (enterotoxin) –absorbed in bloodstream (via digestive tract) –1-6 hours after eating –nausea, vomiting, abdominal pain, diarrhea –epidemiology from skin of food handlers incubate and grow –custard-filled bakery goods –dairy products –processed meats –potato salad –various canned goods

14. © 2004 Wadsworth – Thomson Learning Other food poisoning Clostridium perfringes –less severe –absorption of toxin –cooked meats and gravy spores not killed by cooking meat spores germinate when gravy incubates –heat lamps, warmers toxin produced –symptoms appear with 10-24 hours recovery within 24 hours

15. © 2004 Wadsworth – Thomson Learning Other food poisoning Bacillus cereus –spore former –vegetative cells incubate –two different enterotoxins heat-stable: vomiting –rice heat-labile: diarrhea –meat and vegetables

16. © 2004 Wadsworth – Thomson Learning Rotavirus Gastroenteritis –damages intestinal epithelial –watery diarrhea fever vomiting nausea –fecal/oral route infants and children

17. © 2004 Wadsworth – Thomson Learning Norwalk agents Gastroenteritis –fecal-oral route –symptoms nausea vomiting diarrhea crampy abdominal pain –older children and adults –incubation--48 hrs self-limiting disease

18. © 2004 Wadsworth – Thomson Learning Protozoan infections Amoebic dysentery –Entamoeba histolytica invasive colitis extraintestinal amoebiasis –widespread infection bloody mucoid stools fever abdominal pains Giardiasis –Giardia lamblia –transmission of cyst contaminated water person-person contact

19. © 2004 Wadsworth – Thomson Learning Protozoan infections Balantidiasis –Balantidium coli invade epithelium of colon diarrheal stools –blood and pus Cryptosporidiosis –Cryptospridium abdominal pain watery, bloodless diarrhea municipal outbreaks

20. © 2004 Wadsworth – Thomson Learning Helminthic infections Pinworm –small, white, roundworm –females leave intestine to lay egg Ascaris lumbricoides –roundworm –lifecycle includes intestine, blood, lungs Hookworm –suck blood from host Strongyloides stercoralis –warm, moist climates –multiple reinfection

21. © 2004 Wadsworth – Thomson Learning Helminthic infections Whipworm –Trichuris trichiura –whiplike roundworm Trichinosis –Trichinella spiralis –fever, muscle pain, malaise –larvae migrating through tissues Tapeworms –Taenia spp. –Flatworms

22. © 2004 Wadsworth – Thomson Learning Hepatitis A virus –RNA virus –fecal-oral spread –infectious hepatitis

23. © 2004 Wadsworth – Thomson Learning Hepatitis B virus DNA virus –three antigens HBsAg HBcAg HBeAg –three forms Dane particles –full virion spherical –empty envelope tubule –empty envelope Figure 23.17

24. © 2004 Wadsworth – Thomson Learning Hepatitis B virus –serum hepatitis contaminated blood or blood products 50% no symptoms most survive fulminant hepatitis –total liver failure –associated with liver cancer –prevention HBV vaccine –recombinant HBsAg

25. © 2004 Wadsworth – Thomson Learning Other Hepatitis viruses Hepatitis C –Blood or sexual contact –long incubation period six months 50% develop hepatitis Hepatitis Delta agent –coinfection with Hepatitis B Hepatitis E virus –infectious hepatitis –serious during pregnancy

26. © 2004 Wadsworth – Thomson Learning Helminthic Infections Liver Fluke –Fasciola hepatica –sheep liver fluke –Opisthorchis sinensis –Chinese liver fluke Fig 23.18