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  • 1. Institute for Microbiology, Medical Faculty of Masaryk University and St. Anna Faculty Hospital in Brno Agents of digestive system infections – II
  • 2. Bacterial agents of diarrhea and dysentery – I
    • Escherichia coli
    • Most E. coli strains are component (approx. 1 %) of normal intestinal flora
    • - important
    • - essential
    • - beneficial
    • - non-pathogenic in the intestine
    • Only some E. coli strains are pathogenic even in the intestine
  • 3. Escherichia coli www2.mf.uni-lj.si/~mil/bakt2/bakt2.htm
  • 4. Bacterial agents of diarrhea and dysentery – I I
    • Escherichia coli strains causing diarrheal disease:
    • ETEC (entero t oxic E. coli ): children in developing countries, traveller´s diarrhea; 2 enterotoxins (heat-labile and heat-stable)
    • EPEC (entero p athogenic E. coli ): O55, O111; small infants; disruption of microvillus structure
    • EIEC (entero i nvasive E. coli ): similar to Shigella ; invasion of colonic cells
    • EHEC (entero h aemorrhagic E. coli ): O157:H7; 2 cytotoxic Shigatoxins, destruction of microvilli; hemorrhagic colitis & hemolytic-uremic syndrome
  • 5. E. coli types http://microbewiki.kenyon.edu/index.php/Escherichia
  • 6. Bacterial agents of diarrhea and dysentery – II I
    • Salmonella
    • Taxonomical remarks:
    • There are >4.000 salmonella serotypes
    • Official names of them are inconvenient :
    • The most frequent salmonella:
    • Salmonella enterica subspecies enterica serotype enteritidis
    • The most important salmonella:
    • Salmonella enterica subspecies enterica serotype typhi
    • Instead of them we can use more useful names:
    • Salmonella Enteritidis
    • Salmonella Typhi
  • 7. Salmonella - MAL agar Photo O. Zahradníček.
  • 8. Bacterial agents of diarrhea and dysentery – I V
    • Two types of salmonella infections:
    • Systemic infections (enteric fever): S. Typhi, S. Paratyphi A – C
    • Gastroenteritis (salmonellosis): remaining >4.000 serotypes
    • Pathogenesis of both starts with the invasion of intestinal epithelia
    • In 1) invasion continues and infection becomes generalized -> little or no diarrhea, but pronounced fever & other general symptoms
    • In 2) infection is localized to ileocaecal region -> diarrhea , nausea & vomiting, abdominal pain, temperature may be elevated
  • 9. Bacterial agents of diarrhea and dysentery – V
    • Diagnosis & treatment of salmonella infections:
    • Enteric fever (reservoir: human beings only):
    • Detection of salmonellae in blood, urine and stool (on special media), later detection of antibodies ( Widal reaction), in suspected carriers examination of duodenal fluid
    • Treatment: antibiotics ( chloramphenicol , fluorochinolones, ampicillin, cotrimoxazol)
    • 2) Gastroenteritis (reservoir: poultry & animals):
    • Examination of stool only
    • Treatment: symptomatic only, no antibiotics
  • 10. Bacterial agents of diarrhea and dysentery – V I
    • Campylobacter jejuni
    • As common as salmonella (or even more); invades jejunal epithelium ; reservoir: poultry
    • Cultured on a special medium, in an atmosphere of reduced oxygen, at 42 °C
    • Shigella sonnei, S.flexneri, S.boydii, S.dysenteriae
    • Very low infectious dose -> epidemic outbreaks
    • Transmitted only among human beings
    • Invasion of cells of colon and rectum
    • The disease is called bacterial dysentery
  • 11. Campylobacter jejuni www.cdc.gov/ncidod/eid/vol5no1/altekruseG.htm.
  • 12. Bacterial agents of diarrhea and dysentery – VI I
    • Yersinia enterocolitica
    • gastroenteritis, in children also mesenterial lymphadenitis (mimicking acute appendicitis)
    • vector: contaminated food
    • multiplies in refrigerator even at 4 °C
    • Vibrio cholerae
    • Cholera toxin activates adenylate cyclase -> hypersecretion of water & electrolytes -> death by dehydration and electrolyte abnormalities
    • V. cholerae flourishes in water & causes epidemics
    • Vibrio parahaemolyticus : from raw fish & shell-fish
  • 13. Vibrio cholerae http://www.cs.dartmouth.edu/brd/Research/Bio/water-borne-bioterrorism.htm
  • 14. Diarrhea during antibiotic therapy
    • Common after tetracyclines; from excessively multiplied Staphylococcus aureus, Pseudomonas aeruginosa or Candida albicans (the only example of diarrhea of mycotic origin)
    • After lincomycin or clindamycin (but even after other ATB) -> dangerous pseudomembranous colitis caused by Clostridium difficile
    • Patients contaminate the hospital environment with resistant spores
    • Colitis can be treated by metronidazol
  • 15.
    • Direct proof of the toxin A as an antigen is essential because C. difficile can be found in healthy people
    Pr oof of the toxin A in C. difficile . Photo: MÚ archive
  • 16. Viral agents of diarrhea
    • Generally: small, acid- and bile-resistant non-enveloped viruses
    • Rotaviruses ( Reoviridae family)
    • serious diarrhea of young children, epidemics in winter
    • Noroviruses and sapoviruses (formerly agents Norwalk and Sapporo, Caliciviridae family)
    • epidemics in children and adults, too
    • Astroviruses (star-shaped virions)
    • Adenoviruses type 40 and 41
    • Small, round gastroenteritis viruses
  • 17. Rotavirus http://web.uct.ac.za/depts/mmi/stannard/emimages.html
  • 18. Parasitic agents of diarrhea
    • In previously healthy individuals:
    • Entamoeba histolytica : amoebic dysentery
    • Giardia lamblia : giardiasis
    • Cryptosporidium parvum : cryptosporidiosis
    • Cyclospora cayetanensis
    • In AIDS also:
    • Isospora belli (coccidium)
    • Enterocytozoon bieneusi (microsporidium)
    • Strongyloides stercoralis hyperinfection (helminth)
  • 19. Lamblia CD-ROM „Parasite-Tutor“ – Department of Laboratory Medicine, University of Washington, Seatle, WA
  • 20. Other intestinal parasites (helminths)
    • Small intestine:
    • Ascaris lumbricoides (human roundworm)
    • Ancylostoma duodenale (Old World hookworm)
    • Necator americanus (New World hookworm)
    • Strongyloides stercoralis (threadworm)
    • Fasciolopsis buski (giant intestinal fluke)
    • Taenia saginata (beef tapeworm)
    • Taenia solium (pork tapeworm)
    • Hymenolepis nana (dwarf tapeworm)
    • Diphyllobothrium latum (fish tapeworm)
    • Large intestine:
    • Enterobius vermicularis (pinworm)
    • Trichuris trichiura (whipworm)
  • 21. Ascaris lumbricoides egg CD-ROM „Parasite-Tutor“ – Department of Laboratory Medicine, University of Washington, Seatle, WA
  • 22. Food poisoning
    • 1. Intoxication due to a toxin preformed in the food
    • Staphylococcus aureus : heat-stable enterotoxin
    • Clostridium perfringens : heat-labile enterotoxin
    • Bacillus cereus : heat-stable enterotoxin and vomiting toxin (mostly in rice)
    • Clostridium botulinum : heat-labile neurotoxin
    • 2. Intoxication due to invasive microorganisms
    • Salmonella gastroenteritis
    • ETEC and EHEC
    • Listeria monocytogenes
  • 23. Thank you http://www.giantmicrobes.com/images/doll/salmonella.jpg
  • 24. Q1: Alpha-hemolysis
    • Murray:
    • Alpha-hemolysis = viridation = incomplete hemolysis
    • Hemoglobin converted to verdoglobin
    • Votava:
    • Incomplete hemolysis = a type of beta hemolysis
  • 25. Q2: Anaerobes Colonizing bacteria – a key factor in development of parodontal diseases, anaerobic environment
  • 26. Homework 1 – solution Harmenszoon Rembrandt van Rijn ( 1606-1669 ) Anatomy Lecture of Doctor Tulp (1632)
  • 27. Homework 2 Who is the author of this drawing and what is its name?

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