1. PATHOGENESIS

2. Shigella cause bacillary dysentery
There are two types of dysentery
They are : a) Amoebic dysentery
b) Bacillary dysentery

3. Incubation period is long Insidious onset Local abdominal tenderness
AMOEBIC DYSENTERY
BACILLARY DYSENTERY
Incubation period is long
Insidious onset
Local abdominal tenderness
Moderate tenesmus
Fever absent
Short
Sudden onset
Generalised
severe
present

4. Stool consists of blood,mucus,necrotic cells&feacal matter
Frequency less
Volume copious
Blood,mucus,hardly any fecal matter
More
Small

5. LAB DIAGNOSIS Numerous Discrete not agglutinated Absent Few pus cells
AMOEBIC DYSENTERY
BACILLARY DYSENTERY
MICROSCOPY
Few pus cells
RBC agglutinated
Trophozoites present
Charcoat layden crystals present
Numerous
Discrete not agglutinated
Absent

6. Bacilli not demonstrated in stool culture
Mild leucocytosis in blood smear
Serum agglutination negative
Can be demonstrated
Marked leukocytosis
positive

7. Source-infected human beings Mode of transmission
Direct
Fomites
Water
Contaminated food
Flies
In young male homosexuals

8. Minimum infective dose is low
Pathogenecity resemble that of EIEC

9. MECHANISM OF ACTION.
Bacilli infect the epithelial
cells of villi in LI
multiplication
Inflammatory reaction with
capillary thrombosis
Necrosis of epithelial cells

10. VIRULENCE MARKERS ANTIGENS
Sh.dysenteriae type 1 forms an exotoxin.
CONGO RED BINDING TEST.
VIRULENCE MARKERS ANTIGENS
Virulence test.

11. CLINICAL MANIFESTATIONS

12. Incubation period-1 to 7 days. SYMPTOMS
Frequent passage of loose scanty stools containing blood & mucus
Abdominal cramps
Tenesmus
Fever & vomiting

13. In severe cases- bacteremia
COMPLICATIONS.
Arthritis
Toxic neuritis
Conjunctivitis
Parotitis
HUS

14. Severity ranges from mild diarrhoea to acute fulminating dysentery
The whole spectrum of infection is termed as SHIGELLOSIS.
Of 10,000 people ingested with Sh.flexneri
25% asymptomatic
25% transient fever
25%fever with watery diarrhoea
25% typical dysentery

15. EPIDEMIOLOGY

16. Epidemics always accompanies wars,poverty,lack of sanitation.
Source-humans
Cases
Less often carriers

17. ASYLUM DYSENTERY.
In USA
North-Sh.sonnei
South-Sh.flexneri.

18. In INDIA ,all age groups
Flexneri 50-85%
Dysentriae 8-25%
Sonnei 2-24%
Boydii 0-8%

19. In recent years,suddenly Sh. Dysentriae became virulent epidemic form.

20. LAB DIAGNOSIS.

21. Diagnosis depends on isolating bacilli from feaces. 1. SPECIMENS
Diagnosis depends on isolating bacilli from feaces.. 1.SPECIMENS. -fresh stool -rectal swab -ideal specimen -direct swab of an ulcer.

22. 2.TRANSPORT.
Sach’s buffered glycerol saline.
3.DIRECT MICROSCOPY.
Saline & Iodine preparations.
4.CULTURE.
MacConkey’s agar
DCA

23. 5.COLONY MORPHOLOGY&STAINING
NLF
Gram negative
Motility
6.BIOCHEMICAL REACTIONS.
Urease,citrate,H2S,KCN-negative.
7.SLIDE AGGLUTINATION

24. TREATMENT

25. Uncomplicated shigellosis-self limiting.
Dehydration has to be corrected in infants and children
Antibacterial treatment not indicated
In severe cases-nalidixic acid,norfloxacin,other flouroquinolones.

26. PREVENTION
General prophylaxis.
Chemoprophylaxis.
Immunoprophylaxis.

27. Thank you