shigella and camplyobacter and helicobacter.ppt

Gram negative bacteria

1. SHIGELLASHIGELLA
Disease:
dysentery

2. Important propertiesImportant properties
Shigellae are non-lactose- fermenting, gram
negative bacilli.
All have O polysaccharide antigens, that are
used to divide the genus into 4 groups
A,B,C and D.

3. Shigellae differ from Shigellae differ from
Salmonellae in thatSalmonellae in that
1. Shigellae are non-motile.
2. They do not produce H2S.
3. They produce no gas from
the fermentation of glucose.

4. Important speciesImportant species
1. Shigella dysenteriae: causes
the most severe form of the
disease. Has 10 serotypes.
2. S. sonnei: causes mild disease.
Has one serotype.
3. S. boydii. Has 15 serotypes.
4. S. flexneri. Has 6 serotypes.

5. TransmissionTransmission
Shigellosis is only a human disease.
It is transmitted by the fecal-oral route:
through contaminated food or water.
The principal factors in transmission are
the four F’s:
Fingers
Flies
Food and
faeces

6. PathogenesisPathogenesis
The infectious dose is 100 organisms.
Is by invasion of the mucosal cells of
the distal ileum and colon.
Organisms do not penetrate deeper
than mucosa.
Some strains produce an
enterotoxin: shiga toxin.

7. Mucosal destructionMucosal destruction

8. InflammationInflammation

9. PseudomembranePseudomembrane

10. Clinical findingsClinical findings
The incubation period is 1-4 days.
 fever .
Abdominal cramps.
Diarrhoea : first watery, then bloody.
The disease is more severe in children and
the elderly.
It resolves in 2-3 days. Antibiotics can
shorten the course.
There is no chronic carrier state.

11. Laboratory diagnosisLaboratory diagnosis
Specimens: stool or rectal swab.
Microscopy: pus and RBCs.
Culture:
On MacConkey, DCA, Selenite F, and KIA.:
non-lactose fermenter, & no gas.
Motility test: negative.
Urease negative.
Serological tests for serotyping.
Antibiotic susceptibility test.

12. Pus cells in stoolPus cells in stool

14. NON-MOTILE BACTERIANON-MOTILE BACTERIA

16. SEROLOGIC TYPING FOR SEROLOGIC TYPING FOR
Shigella +veShigella +ve..

17. TreatmentTreatment
Fluid and electrolyte replacement.
In severe disease: ciprofloxacin or
septrin is indicated.
Antiperistaltic drugs are
contraindicated: because they
prolong fever, diarrhea and
excretion of the organism.

18. Have a fresh breathHave a fresh breath

19. Campylobacter Campylobacter
jejunijejuni
Disease: enterocolitis

20. Important propertiesImportant properties
Campylobacters are S- or
comma-shaped ,gram
negative bacilli.
They are microaerophilic
(5% O2). And can grow at
42°C.

21. Campylobacter gram stainCampylobacter gram stain

22. C .jejuniC .jejuni

24. TRANSMISSIONTRANSMISSION
Fecal-oral ,
through contaminated food or
water with animal feces eg,
Cattle
Chickens and
Dogs.

25. PathogenesisPathogenesis
Some strains produce
watery diarrhea by an
enterotoxin.
Other strains invade
tissues.

26. Clinical findingsClinical findings
Enterocolitis begins as foul-smelling
watery diarrhea,
Then followed by bloody diarrhea,
fever and abdominal pain.
Infection is associated with Guillian-
Barré syndrome: a common
autoimmune neuromuscular paralysis.

27. Laboratory Laboratory
diagnosisdiagnosis
Stool is cultured in Skirrow’s
medium ( blood agar+A/Bs) ,at
42°C in 5% O2 and 10% CO2.
Campylobacter is oxidase
positive.
And sensitive to nalidixic acid.

28. C .jejuniC .jejuni

29. C .jejuni on cultureC .jejuni on culture

30. TreatmentTreatment
Erythromycin or
ciprofloxacin.

31. Medicine is your home. Enjoy Medicine is your home. Enjoy
itit..

32. Helicobacter pyloriHelicobacter pylori

33. DiseasesDiseases
H. pylori causes:
1. Gastritis.
2. Peptic ulcers.
3. Is a risk factor for gastric
carcinoma.

34. H .pylori gastritisH .pylori gastritis

35. Important propertiesImportant properties
Are very similar to
campylobacters, but
they are urease positive.

36. H .pylori. Histopathological H .pylori. Histopathological
sectionsection

37. PathogenesisPathogenesis
The natural habitat of H.pylori
is the human stomach.
They attach to mucus-secreting
cells, produce ammonia from
urea,
And induce local inflammation.

38. H . Pylori on surfaceH . Pylori on surface

39. Clinical findingsClinical findings
Recurrent abdominal pain.
Gastrointestinal bleeding.

40. Laboratory Laboratory
diagnosisdiagnosis
1. Specimen: biopsy of gastric
mucosa.
2. Gram negative curved bacilli.
3. Cultured on the same media
as campylobacter.

41. H .pylori. HistopatholoyH .pylori. Histopatholoy

42. 4. Urease positive.
5. IgG in serum is evidence of
infection.
6. The urease breath test: by
ingesting radiolabeled urea and
detecting radioactivity in CO2.

43. TreatmentTreatment
Treatment of peptic ulcers
with amoxicillin +
metronidazole + bismuth
salts decreases the
recurrence rate.

44. When?When?
Soooooon.Soooooon.