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