shigella
Post on 25-May-2015
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T. Dolgorsuren T. Dolgorsuren
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Shigella
Belong to Enterobacteriaceae
Non motile, non capsulated
Deoxycholate citrate agar (DCA) selective media (pale color colonies)
Gram negative bacilli
4 SPECIES/SUBGROUPS BASED ON
BIOCHEMICAL AND SEROLOGICAL CHARACTERS /
SHIGELLA DYSENTERIAE SHIGELLA FLEXNERI SHIGELLA BOYDII SHIGELLA SONNEI
Classifications
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Shigella species
Non Fermentation Fermentation
S dysentriae S flexneri
S boydii
S sonnei
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Epidemiology and Clinical Syndromes
Major cause of bacillary dysentery
Estimated 15% of pediatric diarrhea in U.S.
Leading cause of infant diarrhea & mortality
in developing countries
Epidemics of S. dysenteriae type 1 have occurred in Africa and Central America with case fatality rates of 5-15%.
Common in Pediatric age group (1-10 yrs)
Developed world – S sonnei,
developing world – S flexneri
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Shigellosis = Generic term for disease
Transmission by fecal-oral route
Incubation period = 1-3 days
Watery diarrhea with fever; changing to dysentery
Bacillary Dysentry
Passing blood & mucus in the stool
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Infection cycle of Shigella
Shiga toxin exacerbate inflammation by causing ischemia & hemorrhage
Ulcers
Rarely lead to bacteremia
Organisms adhere to colonic lymphoid follicles
Undergo parasite directed phagocytosis
Resist intracellular killing
Move directly from cell to cell
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Pathogenesis Two-stage disease
Early stage
Second stage
Fever attributed to neurotoxic activity of toxin
Dysentery due to adherence and tissue invasion of large intestine (cytotoxic activity of Shiga toxin)
Watery diarrhea attributed to the enterotoxin activity of Shiga toxin in the small intestine
Enterotoxic, neurotoxic and cytotoxicShiga toxin
04/12/23 Dr B V Navaneeth, Dept of Microbiology 10
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Clinical manifestation
Fever
Abdominal cramping & tenderness
Diarrhea / Dysentry
Tenesmus (straining at stools)
Sigmoidoscopy: ulceration Shigellosis in the cecum tissue
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Lab Diagnosis of Dysentry
Specimens Stool, rectal swab from an ulcer
In Xylose lysine deoxycholate agar(XLD) they appear pinkish to reddish colonies while in Heaktoen Enteric Agar (HEA), they give green to blue green colonies
Growth on Selective Growth on Selective MediumMedium
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Treatment
Oral vaccines of Shigella hybrids or Shigella mutants offers immunity for six months to one year
For adults:
Rehydration if necessary
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For childrenCo-trimoxazole or ampicillin + rehydration
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Yet No Licenced
Vaccine
Preventation
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Hand Washing Can Still Save Hand Washing Can Still Save Many from ShigellosisMany from Shigellosis
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www.wikipedia.comwww.slideshare.comwww.polioeradication.orgwww.webmd.comhealthrecent.blogspot.comconxz.blogspot.comwww.findarticles.comEnglish Mongolian medical dictionary“ Халдварт өвчин судлал ” Я. Дагвадорж“ Анагаах ухааны бичил амь судлал”
Sources
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Thank you for
your attention 04/12/23 20
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