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

2. Respiratory viruses – revision
The most important and most common:
influenzavirus A a B
adenoviruses
RSV and metapneumoviruses
parainfluenzaviruses (type 1+3 = Respirovirus, type 2+4 = Rubulavirus)
rhinoviruses
coronaviruses (incl. SARS agent)

3. Other respiratory agents of virological interest – revision
Bacterial agents causing atypical pneumoniae (but diagnosed in virological laboratories):
Mycoplasma pneumoniae – the most common
Coxiella burnetii – Q-fever
Chlamydia (Chlamydophila) psittaci – agent of ornithosis & psittacosis
Chlamydia (Chlamydophila) pneumoniae

4. Etiology of epiglottitis – revision
Epiglottitis acuta:
Serious disease – medical emergency
The child may suffocate!
Practically one and only important agent:
Haemophilus influenzae type b

5. Etiology of laryngitis and tracheitis – revision
Respiratory viruses again but other than agents of nasopharyngitis:
parainfluenza and influenza A viruses & RSV
Bacteria:
C. pneumoniae, possibly Mycopl. pneumoniae, secondarily: S. aureus and Haem. influenzae
laryngotracheitis pseudomembranosa (croup): Corynebacterium diphtheriae

6. Etiology of bronchitis – revision
Acute bronchitis:
Viruses: influenza, parainfluenza, adenoviruses, RSV
Bacteria, secondarily after viruses: pneumococci, Haem. influenzae, Staph. aureus, moraxellae (again “the gang of four”)
Bacteria, primarily: Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis
Chronic bronchitis (cystic fibrosis):
Pseudomonas aeruginosa, Burkholderia cepacia

7. Etiology of bronchiolitis – revision
Isolated bronchiolitis in newborns and infants only:
Pneumovirus (= respiratory syncytial virus = RSV)
Metapneumovirus

8. Different types of pneumoniae – revision
Acute – community-acquired pneumonia
in originally healthy
adults
children
in debilitated persons
after a contact with animals
Acute – nosocomial pneumonia
– VAP = ventilator-associated
early
late
– others
3. Subacute and chronic pneumonia

9. Etiology of pneumoniae I – revision
Acute, community-acquired, in healthy adults
bronchopneumonia and lobar pneumonia:
Streptococcus pneumoniae
Staphylococcus aureus
Haemophilus influenzae type b
atypical pneumonia:
Mycoplasma pneumoniae
Chlamydia pneumoniae
Influenza A virus (during an epidemic only)

10. Etiology of pneumoniae II – revision
Acute, community-acquired, in healthy children
bronchopneumonia:
Haemophilus influenzae type b ( vaccination!)
Streptococcus pneumoniae
Moraxella catarrhalis
In newborns: Streptococcus agalactiae
enterobacteriae
atypical pneumonia:
respiratory viruses (RSV, infl. A, adenoviruses)
Mycoplasma pneumoniae
Chlamydia pneumoniae
in newborns: Chlamydia trachomatis D-K

11. Etiology of pneumoniae III – revision
Acute, community-acquired, in debilitated individuals:
pneumococci, staphylococci, haemophili
Klebsiella pneumoniae (alcoholics)
Legionella pneumophila
In more serious immunodeficiency:
Pneumocystis jirovecii
cytomegalovirus (CMV)
atypical mycobacteria
Nocardia asteroides
aspergilli, candidae

12. Etiology of pneumoniae IV – revision
Acute, community-acquired, after a contact with animals:
Bronchopneumonia
Pasteurella multocida
Francisella tularensis (tularemia)
Atypical pneumonia
Chlamydia psittaci (ornithosis)
Coxiella burnetii (Q-fever)

13. Etiology of pneumoniae V – revision
Acute, nosocomial:
VAP (ventilator-associated pneumonia)
early (up to the 4th day of hospitalization):
sensitive community strains of respiratory agents („gang of 4“)
late (from the 5th day of hospitalization):
resistant hospital strains
Other nosocomial pneumoniae
viruses (RSV, CMV)
legionellae

14. Etiology of pneumoniae VI – revision
Subacute and chronic:
aspiration pneumonia and lung abscesses
Prevotella melaninogenica
Bacteroides fragilis
peptococci and peptostreptococci
lung tuberculosis and mycobacterioses
Mycobacterium tuberculosis
Mycobacterium bovis
atypical mycobacteria (e.g. the complex M. avium–M. intracellulare)
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15. Digestive system a microbiologist´s dreamland
a fruitful microbial garden
its both ends are the „buggiest“ parts of the body
in the colon: approx bacteria/g
normal colonic flora: 99 % anaerobes (above all Bacteroides, Fusobacterium, Clostridium, Peptostreptococcus), only 1 % Enterobacteriaceae (mainly E. coli) & enterococci

16. Mouth cavity – 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 (by the toothbrush)

17. Mouth cavity – II
Dental caries: chronic infection caused by normal oral flora → localized destruction of tooth tissue
Etiology: mouth microbes (mostly Strept. mutans) making acids from food sucrose
Thrush (in Latin soor): coating of Candida albicans; in newborns & debilitated persons
Herpetic stomatitis: primary infection with HSV 1
Ludwig´s angina: polymicrobial anaerobic infection of sublingual and submandibular spaces (Porphyromonas, Prevotella etc.)

18. Oesophagus
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)

19. Stomach
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)

20. 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 dangerous agent is Salmonella Typhi (carriers of typhoid fever)
Granulomatous hepatitis: Q fever, tbc, brucellosis

21. 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)

22. 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 (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

23. Small and large intestine
Bacterial overgrowth syndrome:
After surgery, during depressed peristalsis or gastric achlorhydria the bacteria may overgrow in the small intestine → steatorrhea, deficiency of vitamin B12, 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 (shigellae or amoebae)

24. Etiology of diarrheal disease
Infectious etiology:
Bacterial (most frequent)
Viral
Parasitic
Mycotic
Non-infectious etiology:
Food poisoning
. . .
(to be continued in the next lecture)

25. Homework 2 – solution Leonardo da Vinci (1452-1519): Fetus in the Womb (between 1510-1512)

26. Successful homework solver:
Homework 2 – solution Leonardo da Vinci ( ): Fetus in the Womb (between )
Successful homework solver:
Sacheen Nathwani
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27. Homework 3 Who painted this picture and what is its name?

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Answer and questions
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