Download Bacillary Dysentery (shigellosis)

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
attachment
penetration
multiplication
immunity
common
Bacteria
intestine
penetrate mucus
multiply in epithelia
cell & proper lamina
inflammation
vessel contraction
normal intestinal flora
sIg A
prevent attaching
endotoxin
endogenous pyrogen
superficial mucosal necrosis and ulcer
diarrhea mixed with blood & pus,
abdominal pain
fever
Pathogenesis-toxic
strong - allergy to endotoxin
demethyl-adrenaline
micro-circulatory failure
shock, cerebral edema
cerebral hernia
DIC
Pathology
site of lesion:
entire large bowelsigmoid 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 dysentery
common type
mild type
toxic type
Clinical manifestation
common
type: (typical type)
acute onset ,
shiver, high fever
abdominal pain(tenderness)
diarrhea: stool mixed with
mucus, blood & pus
tenesmus,
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 40oC
dysphoria, lethargy, convulsion
repeatedly,coma.
circulatory & respiratory collapse
diarrhea 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 dysentery
amebic 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 dysentery
rectal & 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 dysentery
general therapy:
live
diet, nurishing
avoid overwork
exercise.
Treatment
etiologic therapy:
sensitive antibiotics
used in turn or combined use
according to results of culture
enema
expectant 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