Shigella is a gram-negative rod bacteria that causes the infectious disease bacillary dysentery in humans. There are four species of Shigella - S. dysenteriae, S. flexneri, S. sonnei, and S. boydii - which are classified based on their O antigens. Shigella infection results in diarrhea, dysentery, fever, and abdominal pain and is transmitted through the fecal-oral route. In the lab, Shigella can be identified by culturing samples on nutrient agar, MacConkey agar, or Salmonella-Shigella agar where they form colorless colonies. Treatment involves fluid replacement and antibiotics. Vibrio bacteria are

1. PREPEARED BY;
UBAID ULLAH NAWAB
BS SURGICAL KMU-IPMS
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2. SHIGELLA
 Important points:
 Gram negative rods.
 Genus name .
 Present in enteric tract.
 Non lactose fermenting
 Non motile
 Do not produce H2S
 Only human is reservoir.
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3. SHIGELLA -SPECIES
 Shigella species are classified biochemically and serologically by their O
antigen.
 Shigella dysenteriae
 Shigella flexneri
 Shigella sonnei
 Shigella boydii
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4. DISEASE CAUSED BY SHIGELLA
 Shigella species caused enterocolitis.
 Enterocolitis caused by shigella is often called bacillary dysentery.
 Symptoms of enterocolitis:
 Diarrhea
 Dysentary
 Fever
 Tiredness
 Malaise
 Stomach pain
 Vomiting and nausea.
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5. PATHOGENESIS OF SHIGELLA
 Shigella produce shiga toxin which has two sub units. A and B sub
units. The B unit of S. Toxin binds with receptors( glycolipid
globotriaosylceramide (Gb3)) of endothelial mucosal cells and enter to
host cell where inhibit protein synthesis. Also mainly act on lining of
blood vessels, vascular endothelium so at the end hemorrhage
eventually occurs.
 Shigella also invade on lymphoid cells. entering the cells via
phagocytosis forming endosome. Also have the ability to lyse
endosome and replicate in their cytoplasm.
 Endotoxin which is heat stable and elicit variety of inflammatory
responses. O antigen is immunogenic and lipid A is pathogenic.
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6. PATHOGENESIS OF SHIGELLA
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7. LAB DIAGNOSIS
The species can be identified via culture test.
 Sample -----culture swab
 Culture ……nutrient agar
 macConky agar or SS agar.
 Colorless colony…….show salmonella or shegilla.
 Red/pink colony…….E.coli, klebsiella etc.
 macConky agar is superior over SS agar for isolation of shigella dysenteriae
type 1.
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8. TREATMENT
 Fluid and electrolytes replacement.
 Antibiotics are also prescribed.
 Note: it is transmitted through fecal-oral route.
 Prevention: hygienic condition.
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9. VIBRIO
 Gram negative rods.
 Genus name.
 Comma shaped.
 Associated with foodborne infection.
 Motile.
 cause disease in fishes such as shellfish and oyster etc.
 Zoonotic; a disease transmitted from animals to people.
 Mortality among marine life.
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10. VIBRIO
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11. VIBRIO CHOLERAE
 Causative agent of cholera .
 Transmitted by fecal oral route.
 Present in inadequate raw cooked food.
 Vibrio has GbpA (N acetyle glucosaminebinding protein) /CbpA (chitin
binding protein) which have binding capacity with chitin and intestinal
mucosa. It uses chitin as a source of nitrogen and carbon with the help of
chitinases.
 Vibrio cholerae secrete mucinase which dissolves glycoprotein coating
(mucin) over the intestinal mucosa.
 After adherering v.cholerae release enterotoxins (choleragin).
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12. PATHOGENESIS
 Choleragin consist of A and B sun units. the B sub unit which is pentamer
composed of five identical proteins, binds with ganglioside receptor on the
surface of enterocyte. A sub unit inserted to cytoplasm catalyses the addition of
ADP ribose to Gs protein due to which the receptor on Gs protein ,,on ,, so the
adenyle cyclate binds with Gs protein due to which adenyl cyclase become
activated and converted ATP to cAMP which in turn activates protein kinases
which phosphorylates cation channels in cell membrane and opened, resulting
in the loss of water and ions from cells. The watery efflux enters the lumen of
gut, resulting in a massive watery diarrhea.
 No red blood cells and white blood cells in the stool.
 Rice-water stool is a term applied for non blood fecal matter.
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13. PATHOGENESIS
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14. LAB DIAGNOSIS
 Sample…..culture swab
 Culture…..nutrient agar
 macConky agar
 Colorless colony……show vibrio cholerae
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15. VIBRIO PARAHAEMOLYTICUS
 Vibrio parahaemolyticus is a marine organism transmitted by ingestion of
raw and undercooked seafood.
 Like choleragen, it also release enterotoxin .
 Symptoms;
 Watery diarrhea
 Abdominal cramps
 Fever
 Malaise
 Nausea and vomiting
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16. VIBRIO PARAHAEMOLYTICUS
 Vibrio parahaemolyticus grow in 8% Nacl solution whereas vibrio
cholerae does not grow.
 No specific treatment is indicated, because the disease is relatively mild
and self-limited.
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17. VIBRIO VULNIFICUS
 Vibrio vulnificus is also a marine organism.
 Survive in warm salty water.
 It causes;
 Cellulitis: skin and soft tissue infection.
 Septicemia; when bacteria enter the body and circulates in blood and
replicates and the body shows immunological response to cause
inflammation.
 Sepsis; poisoning of blood. sepsis is serious complication of septicimia.
 Hemorrhage bullae; bubble like cavity filled with blood.
 Cirrhosis; chronic liver disease.
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18. VIBRIO VULNIFICUS DISEASES
Hemorrhage bullae Cellulitis10 Dec 2019 18

19. THANK YOU
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