4. Agents of digestive system infections – II

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4. Agents of digestive system infections – II Institute for Microbiology, Medical Faculty of Masaryk University and St. Anna Faculty Hospital in Brno Miroslav Votava 4. Agents of digestive system infections – II Lecture for 3rd-year students 10th October, 2014

Digestive system – revision a microbiologist´s dreamland a fruitful microbial garden its both ends are the „buggiest“ parts of the body in the colon: approx. 1012 bacteria/g normal colonic flora: 99 % anaerobes (above all Bacteroides, Fusobacterium, Clostridium, Peptostreptococcus), only 1 % Enterobacteriaceae (mainly E. coli) & enterococci

Mouth cavity – revision I Normal flora: viridans (= α-haemolytic) streptococci (e.g. Streptococcus salivarius) oral neisseriae (e.g. Neisseria subflava) haemophili of very low pathogenicity (e.g. Haemophilus parainfluenzae) Dental plaque: adherent microbial layer at the tooth surface consisting of 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

Mouth cavity – revision II Dental caries: chronic infection 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.)

Oesophagus – revision Infections of oesophagus never occur in previously healthy individuals Oesophagitis can be seen only in severely immunocompromised persons (in AIDS or after a chemotherapy) Etiology: Candida albicans Cytomegalovirus (CMV)

Stomach – revision Stomach = a sterilization chamber killing most of the swallowed microbes by means of HCl Exception: Helicobacter pylori It produces a potent urease and by hydrolyzing tissue urea it increases pH around itself (1 molecule of urea NH2-CO-NH2 + H2O → → 1 molecule of CO2 + 2 molecules of NH3) Helicobacter pylori causes: chronic gastritis peptic ulcers (Warren & Marshall, Nobel price in 2005)

Biliary tree & the liver I – revision Acute cholecystitis (colic, jaundice, fever): obstruction due to gallstones Etiology: intestinal bacteria (E. coli etc.) Complication: ascending cholangitis Chronic cholecystitis: the most dangerous agent is Salmonella Typhi (carriers of typhoid fever) Granulomatous hepatitis: Q fever, tbc, brucellosis

Biliary tree & the liver II – revision 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)

Infections which start in the digestive tract – revision Enteric fever (typhoid fever and paratyphoid fever): Salmonella Typhi, Salmonella Paratyphi A, B and C Listeriosis: Listeria monocytogenes (dangerous for the fetus) Peritonitis (e.g. after appendicitis or an injury): colonic flora (Bacteroides fragilis + other anaerobes + mixture of facultative anaerobes) Viral hepatitis: HAV, HBV, HCV, HDV, HEV

Small and large intestine - revision Bacterial overgrowth syndrome: After surgery, during depressed peristalsis or gastric achlorhydria bacteria may overgrow in the small intestine → steatorrhoea, deficiency of vitamin B12, diarrhoea, 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

Etiology of diarrhoeal disease – revision Infectious etiology: Bacterial (the most frequent) Viral Parasitic Mycotic Non-infectious etiology: Food poisoning - - -

Bacterial agents of diarrhoea and dysentery – I Escherichia coli Most E. coli strains are a 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 (see the next slide)

Bacterial agents of diarrhoea and dysentery – II Escherichia coli strains causing diarrhoeal disease: ETEC (enterotoxic E. coli): children in developing countries, traveller´s diarrhea; 2 enterotoxins (heat-labile and heat-stable) EPEC (enteropathogenic E. coli): O55, O111; small infants; disruption of microvillus structure EIEC (enteroinvasive E. coli): similar to shigellae → dysentery-like disease ; invasion of colonic cells EHEC (enterohaemorrhagic E. coli): O157:H7; 2 cytotoxic shigatoxins, destruction of microvilli; hemorrhagic colitis & hemolytic-uremic syndrome (HUS); in 2011 strain O104:H4

Bacterial agents of diarrhoea and dysentery – III Salmonella Taxonomical remarks: There are >4.000 salmonella serotypes Official names of them are very inconvenient: The most frequent salmonella: Salmonella enterica subspecies enterica serotype enteritidis The most important salmonella: Salmonella enterica subspecies enterica serotype typhi Instead we can use more useful names: Salmonella Enteritidis Salmonella Typhi

Bacterial agents of diarrhoea and dysentery – IV Two types of salmonella infections: Systemic infections (enteric fever = typhoid 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 diarrhoea, but pronounced fever & other general symptoms In 2) infection is localized to ileocaecal region → diarrhoea, nausea & vomiting, abdominal pain, temperature may be elevated

Bacterial agents of diarrhoea 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

Bacterial agents of diarrhoea and dysentery – VI Campylobacter jejuni Even more common then salmonella; it invades jejunal epithelium ; reservoir: poultry Cultured on a special medium only, 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

Bacterial agents of diarrhoea and dysentery – VII Yersinia enterocolitica gastroenteritis, in children also mesenterial lymphadenitis (mimicking acute appendicitis) vector: contaminated food the microbe 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

Diarrhoea during antibiotic therapy Common after tetracyclines; from excessively multiplied Staphylococcus aureus, Pseudomonas aeruginosa or Candida albicans (the example of diarrhoea 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

Viral agents of diarrhoea Generally: small, acid- and bile-resistant non-enveloped viruses Rotaviruses (Reoviridae family) serious diarrhoea 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

Parasitic agents of diarrhoea 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)

Other intestinal parasites not causing diarrhoea (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)

Food poisoning 1. Intoxication due to a toxin preformed in the food: 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 the infection with an invasive microorganism: Salmonella gastroenteritis ETEC and EHEC (e.g. O157:H7) Listeria monocytogenes - - -

Homework 3 – solution Paulus Peeter Rubens (1577-1640): Goddess of health Hygiene (1615)

Homework 3 – detail Paulus Peeter Rubens (1577-1640): Goddess of health Hygiene (1615)

Successful homework solver: Homework 3 Paulus Peeter Rubens (1577-1640): Goddess of health Hygiene (1615) Successful homework solver: Again, Sacheen Nathwani Congratulation!

Homework 4 Who painted this picture and what is its name?

Thank you for your attention Answer and questions The solution of the homework and possible questions please mail to the address mvotava@med.muni.cz Thank you for your attention