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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