Shigella

Question 1

General Characteristics (4)

Answer 1

NON-MOTILE
NON-CAPSULATED
LACTOSE NON-FERMENTER (S.sonnei is late lactose fermenter after 24h incubation)
Closely related to E.coli

Question 2

Species (4)

Answer 2

Shigella dysenteriae
Shigella flexneri
Shigella boydii
Shigella sonnei

Question 3

Disease

Answer 3

Bacillary dysentery

S.dysenteriae (particularly serotype 1) causes very severe disease, and S.sonnei causes mild disease

Question 4

Virulence Factors (4)

Answer 4

1- INVASION and MULTIPLICATION of COLONIC MUCOSA producing ULCER
2- Invasion mediated by INVASION PLASMID which encodes invasion plasmid antigens (Outer membrane proteins)
3- Production of ENTEROTOXINS (ShET 1 and 2) which mediate WATERY DIARRHEA preceding DYSENTRY
4- S.dysenteriae 1produces SHIGA TOXIN similar to that or EHEC resulting in HUS

Question 5

HUS (6)

Answer 5

Progressive renal failure, hemolytic anemia, thrombocytopenia
MOST COMMON cause of ACUTE KIDNEY INJURY in CHILDREN
Classified into TWO MAIN categories, depending on whether it is associated with Shiga toxin
Predominantly occurs in infants and children after PRODROMAL DIARRHEA
SUPPORTIVE treatment
Bacterial infections many include: S.dysenteriae, E.coli, S.typhi, C.jejuni, Y.pseudotuberculosis

Question 6

Transmission

Answer 6

Person to person

Question 7

Reservoir

Answer 7

Humans (main)

Nonhuman primates (monkeys, chimpanzees)

Question 8

Developing countries

Answer 8

S.dysenteriae

Question 9

Developed countries

Answer 9

S.sonnei