Bacillary Dysentery (shigellosis) Dept. Of Infectious Disease Huang Fen
Bacillary Dysentery (shigellosis)
Dept. Of Infectious DiseaseHuang Fen
DefinitionAcute 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 severeS. flexneri: the epidemic group
and easily turn to chronicS. boydii: tropical and subonS. sonnei: the most mild
EtiologyPathogenicity:
- virulence endotoxin - exotoxin - invasiveness (attach-penetrate-multiply)
Resistance: Strong, 1-2week in fruits,vegetable and dirty soil, heat for 60 30 min℃
EpidemiologySource of infection:
patients and carriersRoute of transmission:
fecal-oral routeSuceptibility of population:
immunity after infection is short and unsteady, no cross-immune
Epidemiology Epidemic features:
season: summer & fallFlexneri, Soneii, dysenteryage: 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 manifestationIncubation period:
1-2 day, (hours to 7 days)Acute dysentery
common type mild typetoxic type
Clinical manifestationcommon type: (typical type)
acute onset , shiver, high feverabdominal pain(tenderness)diarrhea: stool mixed with
mucus, blood & pustenesmus, 1 week
Clinical manifestationmild type: ( atypical type)
caused by S. sonneilow fever or no feverabdominal pain is mildstool mixed with mucus, without
blood & pusdiagnosis by isolation of bacteria3~7d
Clinical manifestationtoxic 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 typeacute attack type
Clinical manifestationchronic 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 Findingsdirect microscopic examination:
WBC, RBC, pus cellsbacteria 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
TreatmentCommon dysenteryToxic dysentery
general treatmentpathogenic treatment :
ofloxine Ampicillin given by IV
Treatmentsymptomatic 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.
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