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PATHOGENESIS. Shigella cause bacillary dysentery There are two types of dysentery They are : a) Amoebic dysentery b) Bacillary dysentery. AMOEBIC DYSENTERY. BACILLARY DYSENTERY. Incubation period is long Insidious onset Local abdominal tenderness Moderate tenesmus

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slide2
Shigella cause bacillary dysentery
  • There are two types of dysentery
  • They are : a) Amoebic dysentery
  • b) Bacillary dysentery
slide3
AMOEBIC DYSENTERY

BACILLARY DYSENTERY

  • Incubation period is long
  • Insidious onset
  • Local abdominal tenderness
  • Moderate tenesmus
  • Fever absent
  • Short
  • Sudden onset
  • Generalised
  • severe
  • present
slide4
Stool consists of blood,mucus,necroticcells&feacal matter
  • Frequency less
  • Volume copious
  • Blood,mucus,hardly any fecal matter
  • More
  • Small
lab diagnosis
LAB DIAGNOSIS

AMOEBIC DYSENTERY

BACILLARY DYSENTERY

  • MICROSCOPY
  • Few pus cells
  • RBC agglutinated
  • Trophozoites present
  • Charcoatlayden crystals present
  • Numerous
  • Discrete not agglutinated
  • Absent
  • Absent
slide6
Bacilli not demonstrated in stool culture
  • Mild leucocytosis in blood smear
  • Serum agglutination negative
  • Can be demonstrated
  • Marked leukocytosis
  • positive
slide7
Source-infected human beings
  • Mode of transmission
    • Direct
    • Fomites
    • Water
    • Contaminated food
    • Flies
    • In young male homosexuals
slide8
Minimum infective dose is low
  • Pathogenecity resemble that of EIEC
slide9
MECHANISM OF ACTION.
  • Bacilli infect the epithelial

cells of villi in LI

multiplication

Inflammatory reaction with

capillary thrombosis

Necrosis of epithelial cells

slide10
Sh.dysenteriae type 1 forms an exotoxin.
  • CONGO RED BINDING TEST.
  • VIRULENCE MARKERS ANTIGENS
        • Virulence test.
slide12
Incubation period-1 to 7 days.
  • SYMPTOMS
    • Frequent passage of loose scanty stools containing blood & mucus
    • Abdominal cramps
    • Tenesmus
    • Fever & vomiting
slide13
In severe cases- bacteremia
  • COMPLICATIONS.
    • Arthritis
    • Toxic neuritis
    • Conjunctivitis
    • Parotitis
    • HUS
slide14
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
slide16
Epidemics always accompanies wars,poverty,lack of sanitation.
  • Source-humans
        • Cases
        • Less often carriers
slide17
ASYLUM DYSENTERY.
  • In USA
    • North-Sh.sonnei
    • South-Sh.flexneri.
slide18
In INDIA ,all age groups
    • Flexneri 50-85%
    • Dysentriae 8-25%
    • Sonnei 2-24%
    • Boydii 0-8%
slide21
Diagnosis depends on isolating bacilli from feaces.. 1.SPECIMENS.

-fresh stool

-rectal swab

-ideal specimen

-direct swab of an ulcer.

slide22
2.TRANSPORT.
  • Sach’s buffered glycerol saline.

3.DIRECT MICROSCOPY.

  • Saline & Iodine preparations.

4.CULTURE.

  • MacConkey’s agar
  • DCA
slide23
5.COLONY MORPHOLOGY&STAINING
  • NLF
  • Gram negative
  • Motility

6.BIOCHEMICAL REACTIONS.

  • Urease,citrate,H2S,KCN-negative.

7.SLIDE AGGLUTINATION

slide25
Uncomplicated shigellosis-self limiting.
  • Dehydration has to be corrected in infants and children
  • Antibacterial treatment not indicated
  • In severe cases-nalidixicacid,norfloxacin,otherflouroquinolones.
prevention
PREVENTION
  • General prophylaxis.
  • Chemoprophylaxis.
  • Immunoprophylaxis.
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