Bacillary Dysentery (shigellosis)

Dept. Of Infectious Disease

Wang Jingyan

Definition Acute infectious disease of intestine caused by d

ysentery bacilli Place of lesion: sigmoid & rectum Pathological feature: diffuse fibrious exudative

inflammation Clinical manifestation: fever, abdominal pain,

diarrhea, tenesmus , stool mixed with blood, mucus & pus. Even companied with marked toxicity and shock,toxic-encepholopthy.

Etiology Causative organism: dysentery bacilli, genus shigell

a, gram-stain negative, short rod,non-motile

Groups: 4 groups & 50 serotypes - S. Dysenteriae-the most sever - S. Flexnerii-the epidemic group and e

asily turn to chronic - S. Boydii-tropical and subon - S. sonnei-the most mild

Etiology Pathogenicity: - virulence (endotoxin) - interotoxin (exotoxin) - invasiveness (attach-penetrate-multiply)

Resistance: Strong.1-2week in fruits,vegetable and dirty soil. heat for 60 30 min℃

Epidemiology Source of infection: - patients - carriers Route of transmission: fecal-oral route Suceptibility of population:immunity after infection i

s short and unstead,no cross-immune

Epidemic features: - season: summer & fall - Flexneri, Soneii, dysentery - age: younger children

Pathogenesis Number of bacteria toxicity immunity invasiveness - attachment - penetration - multiplication

Pathogenesis-commonBacteria

intestine

Normal bacteria florasIg A

Prevent attaching

Penetrate mucus

Multiply in epithelia cell & proper lamina

endotoxin

Endogenous pyrogen fever

Inflammationvessel contraction

Superficial mucosal in,nec and ulcer

Diarrhea mixed with blood & pus, abdominalache

Pathogenesis-toxic

Strong - allergy to endotoxin

Demethyl-adrenaline

Micro-circulatory failure

Shock, DIC, cerebral edema

cerebral hernia

PathologySite of lesion: entire large bowel-colone,

sigmoid & rectumFeature: acute: diffuse fibrinous exudative inflam

mation, hyperemia, edema, leukocyte infiltration, superficial necrosis

chronic: edema, polypoid hyperplasis toxic: endothelial cell of micro-capillary

necrosis

Clinical manifestation Incubation period: 1-2 day, (Hrs. To 7 days)

Acute dysentery common type: onset in sudden, shiver, high fever abdominal pain diarrhea:stool mixed with blood, mucus & pus tenesmus, continence

Clinical manifestation Acute dysentery mild type: caused by S. sonnei low fever or no fever Abdominal pain is mild stool mixed with mucus, without blood & pus diagnosis by isolation bacteria

Clinical manifestation Acute dysentery:

Toxic type: Age: 2 to 7 yrs. Abrupt onset, high fever, Trise to 40oC Listlessness,lethargy,convulsion,coma. circulatory & respiratory collapse diarrhea mild or absent at beginning shock form: septic shock brain form: respiratory failure mixed form

Clinical manifestation Chronic dysentery: > 2 months Chronic delayed type:diahhrea long-time

and repeated Chronic obscure type: acute history in 1 yea

r, no symptoms, stool culture Pos. or sigmoidscopy

Acute attack type: same as common acute dysentery

Laboratory Findings Blood picture: total WBC count increase, neutrophils increase

Stool examination: direct microscopic exam.: WBC, RBC, pus cells bacteria culture: Sigmoidoscope: shallow ulcer,scar, polyps

Differential diagnosis Acute dysentery Amebic dysentery Entameba histolytica stool: reddish brow, like jam flask-shaped ulcer,Amebic trophozoite Enteritis caused by E. Coli, salmonella,vi

ral diarrhea Intussusception: jelly-like stools, abdominal

mass and absence of fever

Differential diagnosis Chronic dysentery Rectal & colonic carcinoma: no cure for long-term,dro

p of weiht of body non-specific ulcer colitis: no cure for long-term,culture

of stool is negetive, sigmoidoscope:hemorrhage, ulcer,lead pipe.

Chronic schistosomiasis Japonica a. co ntact with the disease-water b. hepatomegaly and splenomegaly c .founding the ova of schistosomiasis Japonica

Toxic dysentery Encephalitis B

brain form:Japaness B encephalitis

a.stool

b.CFS-IgM

c.slowly

d.shock rarely

Treatment Common dysentery Toxic dysentery general treatment Pathogenic treatment :ofloxine or Amp. Given

by IV Synptomatic treatment:Control high fever, con

vulsion: sub-winter sleep Treatment of shock:same as ECM Treatment of cerebral edema: same as EBC

Treatment Chronic dysentery General therapy:live,nurishing,diet,avoid

overwork,excise. Etiologic therapy: sensitive antibiotics used i

n turn or combined use;according to results of culture;enema;expectant treatment.

Prevention

• Control the source of infection: until culture negative

• Interruptted the route of transmission: method of mainly

• Protct the susceptability:F2a-secratory IgA protect 80%-6-12mon

• return