Git1
- 1. Institute for Microbiology, Medical Faculty of Masaryk University and St. Anna Faculty Hospital in Brno Agents of digestive system infections – I
- 2. Digestive system „ a fruitful microbial garden “ Its both ends are the „buggiest“ parts of the body in the colon: approx. 10 12 bacteria/g Normal colonic flora : 99 % anaerobes (Bacteroides, Fusobacterium , Clostridium , Peptostreptococcus ), only 1 % enteric bacteria (mostly E. coli ) & enterococci
- 3. Mouth cavity – I Normal flora: viridans (= α-haemolytic) streptococci (e.g. Streptococcus salivarius ) oral neisseriae (e.g. Neisseria subflava ) haemophili of very low pathogenity (e.g. Haemophilus parainfluenzae ) D ental plaque: adherent microbial layer at the tooth surface made up from living and dead bacteria and their products together with components from the saliva In essence, dental plaque is a biofilm It cannot be washed off, only mechanically removed
- 6. B i ofilm Bacteria can regulatethe quantity of their population by regulative compounds Process – quorum sensing More resistant to desinfectants antibiotics immune rection A product of normal flora (which is positive) and pathogens as well Foto: Veronika Holá
- 8. Mouth cavity – II Dental caries: chronic infections caused by normal oral flora -> localized destruction of tooth tissue Etiology: mouth microbes (mostly Strept. mutans ) making acids from sucrose in food Thrush (in Latin soor): Candida albicans It occurs mostly in newborns Herpetic stomatitis: primary infection with HSV 1 Ludwig´s angina: polymicrobial anaerobic infection of sublingual and submandibular spaces ( Porphyromonas , Prevotella etc.)
- 12. Oesophagus Infections never in previously healthy individuals Only in severely immunocompromised persons (AIDS): Candida albicans Cytomegalovirus (CMV)
- 13. Stomach Stomach = a sterilization chamber killing by means of HCl most of swallowed microbes Exception: Helicobacter pylori It produces a potent urease and b y splitting tissue urea it i n creases pH around itself (1 molecule of urea -> 1 C O 2 + 2 NH 3 ) H. pylori causes chronic gastritis peptic ulcers (Nobel price in 2005)
- 16. Biliary tree & the liver – I Acute cholecystitis (colic, jaundice, fever): obstruction due to gallstones Etiology: intestinal bacteria ( E. coli etc.) Complication: ascending cholangitis Chronic cholecystitis: the most important is Salmonella Typhi (carriers of typhoid fever) Granulomatous hepatitis: Q fever, tbc, brucellosis
- 17. Biliary tree & the liver – II Parasitic infections of the liver: Amoebiasis ( Entamoeba histolytica : liver abscess) Malaria (the very first, clinically silent part of the life cycle of malaric plasmodia) Leishmaniasis ( Leishmania donovani : kala-azar, L. infantum ) Schistosomiasis (eggs of Schistosoma japonicum , less often S. mansoni )
- 18. Systemic infections which start in the digestive tract Enteric fever (typhoid fever and paratyphoid fever): Salmonella Typhi, Salmonella Paratyphi A, B and C Listeriosis : Listeria monocytogenes Peritonitis : colonic flora ( Bacteroides fragilis + other anaerobes + mixture of facultative anaerobes) Viral hepatitis : HAV, HBV, HCV, HDV, HEV
- 19. Small and large intestine Bacterial overgrowth syndrome: After surgery, depressed peristalsis, or gastric achlorhydria bacteria may overgrowth in the small intestine -> steatorrhea, deficiency of vitamin B 12 , diarrhea , malabsorption of vitamins A and D Diarrhea : increase in daily amount of stool water – common intestinal response to many agents Dysentery : acute inflammation of the colon -> abdominal pain & small-volume stools with blood, pus and mucus
- 20. Diarrheal disease Infectious: Bacterial (most frequent) Viral Parasitic Mycotic Non-infectious: Food poisoning
- 21. „ Homework 1 “ What is the name of the picture and of its author?