Git2
- 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
- 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
- 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
- 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
- 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
- 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?