The document discusses bacillary dysentery caused by various Shigella species, including their biochemical properties, modes of transmission, and epidemiology. Key characteristics include the disease being primarily communicable through the fecal-oral route and marked by symptoms such as blood-stained stools, fever, and vomiting. Treatment involves fluid replacement, antibiotics for severe cases, and emphasizes the importance of sanitation practices.

2.  Clinical condition of multiple origin,
characterised by the frequent passage of
blood stained mucopurulent stools.
 Two common types:
 Bacillary
 amoebic

3. • Tribe – Escherechiae
• Genus – Shigella
• Species – S. flexneri – Flexner (1900),
S. sonne – Sonne (1915), S. boydii – Boyd
(1931)

4. •GN rods, non-motile, non-sporing, non-
capsulated, fimbriae may be present
•Aerobes and facultative anaerobes, 10–40°C
•Nutrient agar – 2–3 mm translucent colonies,
S. sonnei – larger and opaque

5. •MA – NLF, S. sonnei – LLF
•DCA – selective medium – colourless colonies
•XLD – xylose lysine deoxycholate – red
colonies
•SS – Salmonella, Shigella – colourless colonies

6. •Enrichment media – selenite F broth
•Transport medium – 30% buffer glycerol
saline solution
•Biochemical reactions
•MR +ve, reduce nitrates – nitrites, NLF/LLF,
VP, citrate −ve

7. • Mannitol non-fermenter, S. dysenteriae type 1
• 12 serotypes, type 1; only member that is Sh. shigae,
catalase negative
• Exotoxin – Shiga toxin
• 3 types of toxic activity have been demonstrated
• Neurotoxicity – blood vessels – CNS
• Enterotoxicity – induce inflammation of the epithelial
cells. By decreased secretion of interleukin-8
• cytotoxicity causes cytopathic changes in Vero cells.
Verotoxin it has two subunits B, A–A1 inactivates host
cell 60 s ribosome, interfering with protein synthesis

8. •Sh. schmitzi – indole +ve, ferments sorbitol
and rhamnose
•Serotypes 3-7 ; Large and Sachs (India)

9. •Flexner – mannitol fermenting Philippines
(1900)
•Antigenically most complex – six serotypes
(1–6) and several subtypes (1a, 1b; 2a, 2b;
3a, 3b, 3c; 4a, 4b; 5a, 5b), two antigenic
variants – X and Y are recognised which lack
the type specific antigens

10. •Boyd – India – 1931
•18 serotypes
•Isolated least frequently – bacillary dysentery
•Resembles Sh. flexneri biochemically not
antigenically

11. •Sonne (1915) – Denmark, LLF, L sucrose F,
indole –ve
•Antigenically homogeneous
•Two phases I and II – larger, flatter and
irregular colonies
•Mildest form – bacillary dysentery –
developed countries
•Serologically homogenous -Colicin typing –
26 types

12. •Epidemics – wars, Rwandian civil war 1994
•Britain – shigellosis – young children (asylum
dysentery) Sh. sonnei
•USA; Sh. sonnei – North, Sh. flexneri – South –
carrier rate 0.1–1%
•India; Sh. flexneri – predominant 50–80%, Sh.
dysenteriae – 8–25%, Sh. sonnei – 2–24%, Sh.
boydi – 0–8%
•Sh. dysenteriae type I – epidemics since
1980s, resistant to multiple drugs

13. •Mode of infection – ingestion/feco-oral route,
highly communicable disease
•Incubation period (1–7 days)
•Source of infection – case/carriers
•Infective dose; 10–100 bacilli
•Ingestion – infect epithelial cells in large
intestine – multiply – spread laterally to
adjacent cells – inflammatory reaction –
capillary thrombosis – necrosis – transverse
superficial ulcers

14. •Invasive property
•Exotoxin – less important – non-toxigenic
strains – dysentery
•Invasive property; ability to penetrate
cultured HeLa/Hep-2 cells
•Congo red binding test
•VMA ELISA

15. •Dysentery – loose scanty feces – blood and
mucus
•Fever and vomiting
•Arthritis, toxic neuritis, conjunctivitis,
parotitis, intussusception, hemolytic uremic
syndrome

16. •Isolation
•Specimen; fresh feces, mucus flakes
•Transport medium – Sach’s buffered glycerol
saline
•Enrichment – selenite F broth
•MacConkey and DCA; NLF colonies – motility
and biochemical tests
•Slide agglutination/monovalent and polyvalent

17. • Self-limiting
• Fluid replacement and ORT
• Antibiotics – toxic cases – nalidixic
acid/norfloxacin
• Control – environmental and personal
sanitation
• Five Fs – fingers, fomites, flies, feces and food