Shigellosis. Differential dinosis of colitis.

Question 1

what are the DIFFERENT PATHOGENS CAUSING SHIGELLOSIS?

Answer 1

Shigella dysenteriae,

Shigella flexneri,

s bodii - most severe

Shigella sonnei (most common) 
classified by their o antigens

Question 2

EPIDEMIOLOGY OF SHIGELLA ?

Answer 2

Humans are the only hosts and reservoir

Question 3

what are the CHARACTERISTICS OF SHIGELLOSIS?

Answer 3

family enterobacteriaceae (Gram-)

gram negative rods
produce - SHIGA toxin (ENTEROTOXIN)

and endotoxin

gram negative rods

very low infective dose required such as 10 or more bacteria

SHIGA toxin (ENTEROTOXIN)
hus - acute renal failure - thrombocytopenia , microangiopathic anemia
- hypertension

Question 4

what is the TRANSMISSION OF SHIGELLOSIS ?

Answer 4

fecal oral
oral anal
food contaminated
contaminated water

affects the terminal ileum or colon

Question 5

PATHOGENESIS OF SHIGELLA ?

Answer 5

ingestion

Shigella invade colonic
and rectal cells, including M cells of the follicle-associated epithelium, macrophages, and epithelial cells;

intracellular multiplication:
Shigella lyse the phygocytic vacuole & start replicating in
cytoplasm, UNLIKE SALMONELLA WHICH replicate inside the vacuole
and destruction of colonic mucosa

spread of infection to adjacent cells - via actin filaments (no hematogenous spread) - invade the immune system.

shigella
toxin leads to hemorrhages because it destroys the
endothelium

Question 6

what is the INCUBATION PERIOD OF SHIGELLOSIS ?

Answer 6

0-2 days

very low infective dose required such as 10 or more bacteria

Question 7

what are the CLINICAL FEATURES OF SHIGELLOSIS ?

Answer 7

duration is 2-7 days

high fever
tenesmus
abdominal cramps
inflammatory mucoid bloody diarrhea

vomiting

there is also formation of ulcer - causing the bleeding

s sonnei - mild

=====
shigella is self limiting - 3 days to 1 week

Question 8

whata the COMPLICATIONS OF SHIGELLOSIS ?

Answer 8

HEMOLYTIC UREMIC SYNDROME
nephritic syndrome - this is due to the shiga toxin

intestinal complication -
toxic megacolon ,
colonic perforation ,
intestinal obstruction

febrile seizures

Question 9

DIAGNOSIS OF SHIGELLA ?

Answer 9

fecal leukocytes and erythrocytes

stool culture - because bacteria undergoes lysis
PCR test

mcconkey agar
shigella agar

Question 10

what is the DD OF SHIGELLOSIS ?

Answer 10

ecoli ecoli - 0157:H7
amoebias
salmonella
campylobacter

Question 11

what is the TREATMENT OF SHIGELLOSIS ?

Answer 11

rehydration therapy

and only in severe cases antibiotics - 
first line - 
fluroquinilones - cipro
or 
3rd gen cephalosporins - ceftriaxone

all 3-5 days