Bacillary Dysentery
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Bacillary Dysentry
Shegellosis
Definition:
An acute bacterial infection of the large intestine
Causative Agent:
Aerobic gm –ve bacilli. Four species exist: 1- Sh. Dysenteriae(gp A): namely shigella shiga with its exotoxins causing severe illness.It is the least common.
2-Sh.Flexneri (gp.B): the most common in Egypt. 3- sh.boydii (gp C) 4- Sh. Sonnei (gp D)
Resistance :
It is sensitive to heat [killed at 55°c in one hour]; to phenol & other chemicals. Survive in water, food, milk, &contaminated objects.
Occurrence: more in tropical and temperate climate. It causes about 600,000 deaths/year in the world mainly in children <10 years. Reservoir [source of inf.] Man only…..cases, & carriers (contact, healthy and convalescent) I.P From 12 hours up to 3-4 days. [ranged from 1- 7 days]
Modes of transmission:
[in small confined groups, hospitals, laboratory infection (occupational). 1-
Direct transmission: faecal-oral or hand to mouth infection. 2- Indirect transmission: [flies, dust, contaminated objects, food & water]
Clinical Picture:
Atypical: fever,
abdominal pain, watery diarrhea Typically: former sympt. + tenesmus, loose stool, mucous, blood, pus with prostration.
Complications:
Usually with young children or elderly population. Also, in sh. Shiga infection.
Dehydration Arthritis, Iridocyclitis [Reiter syndrome], it can occur after sh.Flexneri in patients having histocompatibility antigen (HLA-B27). Glomerulonephritis, Haemolytic-Uremic syndrome. Toxic megacolon. Rectal Prolapse can occur in infants or children after severe shegellosis.
Diagnosis: 1-
Clinical: 2- Laboratory: Stool culture (rectal swab)----serological tests. Stool examination: blood, polymorphonuclear leucocytes.
Immunity: The
disease is self-limited lasting from 4-7 days.
Repeated
infection may occur with the same serotype but with a milder form.
Prevention:
1-Environmental sanitation. Correct food handling practice 2- Health education.
Control: A- Cases: Notification, Isolation at home, Disinfection, Treatment: Ampicillin or trimethoprim Release after two –ve stool cultures.(24 hours at least between both)
B-contacts:
Health education. Food handlers excluded and stool culture is done [released after 2 –ve cultures every other day]
C- Epidemic measures: When cases of dysentery occur in a confined group, investigate the outbreak as you have studied. 1- identify the diagnosis., study the possible source, surrounding environment, ….
Shegellosis
Definition:
An acute bacterial infection of the large intestine
Causative Agent:
Aerobic gm –ve bacilli. Four species exist: 1- Sh. Dysenteriae(gp A): namely shigella shiga with its exotoxins causing severe illness.It is the least common.
2-Sh.Flexneri (gp.B): the most common in Egypt. 3- sh.boydii (gp C) 4- Sh. Sonnei (gp D)
Resistance :
It is sensitive to heat [killed at 55°c in one hour]; to phenol & other chemicals. Survive in water, food, milk, &contaminated objects.
Occurrence: more in tropical and temperate climate. It causes about 600,000 deaths/year in the world mainly in children <10 years. Reservoir [source of inf.] Man only…..cases, & carriers (contact, healthy and convalescent) I.P From 12 hours up to 3-4 days. [ranged from 1- 7 days]
Modes of transmission:
[in small confined groups, hospitals, laboratory infection (occupational). 1-
Direct transmission: faecal-oral or hand to mouth infection. 2- Indirect transmission: [flies, dust, contaminated objects, food & water]
Clinical Picture:
Atypical: fever,
abdominal pain, watery diarrhea Typically: former sympt. + tenesmus, loose stool, mucous, blood, pus with prostration.
Complications:
Usually with young children or elderly population. Also, in sh. Shiga infection.
Dehydration Arthritis, Iridocyclitis [Reiter syndrome], it can occur after sh.Flexneri in patients having histocompatibility antigen (HLA-B27). Glomerulonephritis, Haemolytic-Uremic syndrome. Toxic megacolon. Rectal Prolapse can occur in infants or children after severe shegellosis.
Diagnosis: 1-
Clinical: 2- Laboratory: Stool culture (rectal swab)----serological tests. Stool examination: blood, polymorphonuclear leucocytes.
Immunity: The
disease is self-limited lasting from 4-7 days.
Repeated
infection may occur with the same serotype but with a milder form.
Prevention:
1-Environmental sanitation. Correct food handling practice 2- Health education.
Control: A- Cases: Notification, Isolation at home, Disinfection, Treatment: Ampicillin or trimethoprim Release after two –ve stool cultures.(24 hours at least between both)
B-contacts:
Health education. Food handlers excluded and stool culture is done [released after 2 –ve cultures every other day]
C- Epidemic measures: When cases of dysentery occur in a confined group, investigate the outbreak as you have studied. 1- identify the diagnosis., study the possible source, surrounding environment, ….
