Bacillary Dysentery (shigellosis)

Dept. Of Infectious Disease

Huang Fen

Definition

Acute infectious disease of intestine caused by dysentery bacilli(genus shigella)

Place of lesion: sigmoid & rectum

Pathological feature:

diffuse fibrious exudative

inflammation

Definition

Clinical manifestation:

fever, abdominal pain, diarrhea,

tenesmus , stool mixed with

mucus blood, & pus.

even companied with shock,

toxic-encepholopthy.

Etiology

Causative organism:

dysentery bacilli, genus shigella,

gram-stained negative,

non-motile short rod,

Groups: 4 serogroups &47 serotypes

Etiology

S. dysenteriae: the most severe

S. flexneri: the epidemic group

and easily turn to chronic

S. boydii: tropical and subon

S. sonnei: the most mild

Etiology

Pathogenicity: - virulence endotoxin - 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 and carriers

Route of transmission:

fecal-oral route

Suceptibility of population:

immunity after infection is short

and unsteady, no cross-immune

Epidemiology

Epidemic features:

season: summer & fall

Flexneri, Soneii, dysentery

age: younger children

Pathogenesis number of bacteria toxicity invasiveness

attachmentpenetrationmultiplication

immunity

commonBacteria

intestine

normal intestinal florasIg A

prevent attaching

penetrate mucus

multiply in epithelia cell & proper lamina

endotoxin

endogenous pyrogen fever

inflammationvessel contraction

superficial mucosal necrosis and ulcer

diarrhea mixed with blood & pus, abdominal pain

Pathogenesis-toxic

strong - allergy to endotoxin

demethyl-adrenaline DIC

micro-circulatory failure

shock, cerebral edema

cerebral hernia

Pathology site of lesion:

entire large bowel-

sigmoid colon & rectum

feature:

acute: diffuse fibrinous

exudative inflammation,

Pathology hyperemia, edema, leukocyte infiltration, superficial necrosis, ulcer.

chronic: edema, polypoid hyperplasia,

toxic: colon: hyperemia, edema, micro- capillary was invaded

Clinical manifestation

Incubation period: 1-2 day, (hours to 7 days)

Acute dysenterycommon type

mild type

toxic type

Clinical manifestationcommon type: (typical type)

acute onset , shiver, high feverabdominal pain(tenderness)diarrhea: stool mixed with

mucus, blood & pustenesmus, 1 week

Clinical manifestation

mild type: ( atypical type)caused by S. sonnei

low fever or no fever

abdominal pain is mild

stool mixed with mucus, without

blood & pus

diagnosis by isolation of bacteria

3~7d

Clinical manifestation

toxic type:

age: 2 to 7 yrs.abrupt onset, high fever, T 40oCdysphoria, lethargy, convulsion

repeatedly,coma.circulatory & respiratory collapsediarrhea mild or absent at beginning

Clinical manifestation

shock form: septic shock brain form:

dysphoria,lethargy,convulsion

repeatedly,coma, brain hernia. respiratory failure

mixed form

Clinical manifestation

chronic dysentery: > 2 months

chronic delayed type:chronic obscure type

acute attack type

Clinical manifestation

chronic delayed type: long-time and repeated abdominal

pain, diarrhea, stool mixed with

mucus, blood & pus.

with fatigue, anemia, malnutrition.

Clinical manifestation

chronic obscure type: acute history in 1 year, no symptoms,

stool culture positive or sigmoidscopy

acute attack type:

same as common acute dysentery

Laboratory Findings

Blood picture: WBC count increase, (10~20×109/L) neutrophils increase

Stool examination:gross examination: stool mixed with

mucus, blood & pus.

Laboratory Findings

direct microscopic examination: WBC, RBC, pus cells

bacteria culture:PCR:DNA

Sigmoidoscopy: chronic patients shallow ulcer scar polyp

Differential diagnosis

acute dysenteryamebic dysentery

Entamoeba histolytica

stool: reddish brown, like jam

flask-shaped ulcer,

amebic trophozoite

Differential diagnosis

enteritis caused by E. Coli,

salmonella, virus.

intussusception: jam-like stools,

abdominal mass

absence of fever

Differential diagnosis

chronic dysenteryrectal & colonic carcinoma:

no cure for long-term, drop of weight of body

non-specific ulcer colitis: no cure for long-term, culture of stool is negative,

Differential diagnosis

sigmoidoscopy: hemorrhage,

ulcer, lead pipe.

chronic schistosomiasis Japonica contact with the contaminated water

hepatomegaly and splenomegaly

founding the ovum of schistosomiasis

Japonica

Differential diagnosis

toxic dysentery

encephalitis B: highfever,convulsion,coma.• <24h• circulatory failure• stool examination• CSF• meningeal irritation• Specific IgM

Treatment

Common dysentery

Toxic dysentery general treatment

pathogenic treatment :

ofloxine

Ampicillin given by IV

Treatment

symptomatic treatment:• control of high fever,convulsion:

subhibernation • treatment of shock: same as ECM• treatment of cerebral edema:

20% mannitol

Treatment

chronic dysenterygeneral therapy:

live

diet, nurishing

avoid overwork

exercise.

etiologic therapy:

sensitive antibiotics

used in turn or combined use

according to results of culture

enema

expectant treatment.

Treatment

Prevention

Control the source of infection:

until culture negative

Interrupting the route of transmission:

Protecting the susceptible population:

F2a-secretary IgA

protect 80%-6-12mon