Shigella spp

Enterobacteria

family of shigella spp

Gram negative bacilli

gram stain and shape of shigella

Fecal oral or direct person person

method of shigella transmission

Four

serogroups that contain serotypes each with unique biochemical and virulence characteristics

s. flexneri

most common cause of diarrhea among serogroups (endemic in LMICs)

s. boydii and s. dysenteriae

least common cause of diarrhea shigella infections

s sonnei

most common cause of watery diarrhea / travelers diarrhea in high income countries

s flexneri and s dysenteriae

s flexneri and s dysenteriae

shigellosis

characterized by acute inflammatory colits and bloody diarrhea, self limiting resolves in 5-7 days and can be prlonged in immunocomp people

HUS

can occur in certain strains

Type 1 infection

Colonic perforation, intestinal obstruction, and toxic megacolon occur in a ____

Gastric acid

shigella spp. are more resistant to ____ (than other GI pathgoens)

GadAB

part of the glutamate decarboxylase system in shigella acid resistance

AtpAD

part of the ATP synthase system

GadAB and AtpAD

combine to control proton flow and tune intracellular pH used for resistance to gastric acid

Shigella enterotoxin 1 (ShET1)

predominantly produced by s flexneri, iron dependent AB toxin encoded on chromosome, responsible for early phase of diarrhea

Shigella enterotoxin 2 (ShET2)

produced by almost all shigella spp, causes early phase diarrhea

Shiga toxin

AB subunit toxin produced by dysenteric strains, retrograde trafficks to ER, deactivates 28S rRNA, leads to apoptosis and necrosis of cells, responsible for HUS and hemorrhagic colitis

T3SS

shigella use this ss by the mxispa locus on the 220 kb plasmid

IcsA

facilities initial association w NWASP on host cell in shigella invasion

IpaD

blocks pore until cholesterol and sphingomyelin are sensed in shigella invasion

IpaB and IpaC

recruited and form pore in host cell in shigella invasion

IpaBCD

release and bind alpha5B1 integrin to mediated actin rearrangement in shigella invasion

IpgD

dephosphorylates PIP2 into PI5P during phagosome escape of shigella

PI5P

leads to TOM1 recruitment that inhibits endosomal maturation, promotes actin rearrangement to induce more invasion, activates Akt to promote cell survival and promotes recruitment of Rab11 to the point it leads to vacuole rupture during phagosome escape of shigella

Cell cell spread

T3SS gets reactivated when ____ is needed

IcsA

attaches to the old pole of the cell and mimics Cdc4 to recruit NWASP and Arp2/3 to function as actin polymerization complex to mediate propulsion to adjacent cells

Supportive care

treating shigella infections

No

are antibiotics recommended for treating shigella infections?