what are some epidemiological factors associated with shigella?
- S.flexenei mostly in underdeveloped countries
- S.sonnei mostly in developed countries
- Day cares are important setting for outbreak
- fecal and oral route
- mostly pediatric
- low dose required
- contaminated food
- no seasonal variance
what are some characteristics associated with shigella?
- lactose negative
- H2S negative on TSI
- Grouped according to O antigen
- Have capsule K antigen
what are some clinical characteristic associated with shigella?
- might be asymptomatic
- early onset ( 1-3)
- Abdomenol cramps
- Bloody stool
- self limiting
what are some ways to diagnose shigella?
- very fragile in vivo
- culture rectal swab or stool
- use of selective media (HE, XLD which inhibits gram +)
- use of biochemical test
what is the general mechanism of infection and replication in listeria and shigella?
Actin base motility
what does shigella toxin do?
- cleaves 28S rRNA in 60S ribosomal unit
- disrupts protein synthesis
- Lead to cell death
what are factors contributing to pathogonicity of shigella?
- Endotoxin/ lps
- incasion ( IpaA, B, C,D)
- entrotoxin ( induces cell death of macrophage and cell to cell spread) also escape from phagosome
- exotoxin which mediates endothilial damage leading to hemolitic colitis also in some cases hymolytic uremic syndrome
what are some ways to treat shigella?
- antibiotic treatment
- in vitro suseptibility
- start with ampicilin/ trimtroprim and sulfometadoxazole
- treat carriers
- proper swage disposal
- proper hygene
- water chlorinatin
- there is no vaccine
what are some general characteristics of uersinia
- short or clumpy rods
- lactose negative
- grouped according to O antigen
- capsular K antigen
what are some routes of transmission in yersinia?
- host is animal
- Y. pestis which is mostly found in rodents, this is a vector borne disease transmitted bu bite of flea
- pulmonary pleauge which is highly infectious , transmitted person to person and it is arosel.
what are some ways of disease manifestation?
- . bubonic pleauge
- onset after 2 to 6 days
- enlarged tender lymph node, fever and chill
- .septimatic plegue
- fever, chill, abdominal pain, bleeding into skin and other organs
- * both of above can lead to pneumonic plegue
what are some treatments for the plegues?
- chemotherapy ( streptomycin and chloramophonical)
- avoiding rodants
- pest control
- monitoring plegue in rodant population
- use of insectisides
- drug treatment
- no vaccine!!
what mechanism does yersinia use for invasion?
what is the role of YOP in yersinia?
- it help avoid host cell macrophage
- YOP H inhibition of phagocytosis
- YOP J induction of appotosis
what are some factors contribution to pathogenesis of yersinia?
- Endotoxin/ LPS
what is enteric yersinia infeciton mostly associated with?
- intake of contaminated food
- it is more common in winter
- zoonotic > pigs
- mostly in young children
- 4-7 days after exposure
- last 1-3 weeks
- fever, abdominal pain on right side and bloody diarrhea
- usually self limiting
- use TMS or aminoglycoside
where and how does Y.enterocolitis grow and what does it cause?
- it grows at 4C
- also grows on large scale on contaminated blood sample
- cause bacteremia after blood transfusion and septic shock