Dysentery
When possible, patients presenting with signs and symptoms of dysentery
should have stool specimens examined by microscopy to identify Entamoeba
histolytica. Care should be taken to distinguish large white cells (a
nonspecific indicator of dysentery) from trophozoites. Amebic dysentery tends
to be misdiagnosed.
Shigellosis
If a microscope is unavailable for diagnosis, or if definite trophozoites are
not seen, persons with bloody diarrhea should be treated initially for
shigellosis. Appropriate treatment with antimicrobial drugs decreases the
severity and duration of dysentery caused by Shigella and reduces the
duration of pathogen excretion. The selection of an antimicrobial treatment
regimen is often complicated by the presence of multiresistant strains of
Shigella. The choice of a first-line drug should be based on knowledge of
local susceptibility patterns. If no clinical response occurs within 2 days,
the antibiotic should be changed to another recommended for that particular
strain of shigellosis. If no improvement occurs after an additional 2 days of
treatment, the patient should be referred to a hospital or laboratory for
stool microscopy. At this stage, a diagnosis of resistant shigellosis is
still more likely than amebiasis.
Drugs of choice. Treatment guidelines for shigellosis are listed below.
-
Ampicillin
-
Children: 100 mg/kg/day in four divided doses for 5 days.
-
Adults: 500 mg four times daily for 5 days.
-
TMP-SMX
-
Children: 10 mg/kg/day TMP and 50 mg/kg/day SMX in two divided doses for
5 days.
-
Adults: 160 mg TMP and 800 mg SMX twice daily for 5 days.
For strains resistant to these regimens, alternative treatment with nalidixic
acid or tetracycline is indicated.
-
Nalidixic acid
-
55 mg/kg/day in four divided doses for 5 days.
-
Tetracycline
-
50 mg/kg/day in four divided doses for 5 days.
The fluoroquinolones (e.g., ciprofloxacin and ofloxacin) are highly effective
for the treatment of shigellosis, but are expensive and have not yet been
approved for treatment of children or pregnant or lactating women with
shigellosis.
Because multiresistant strains of Shigella have become widespread and because
Shigella strains can rapidly acquire resistance in endemic and epidemic
settings, it is advisable that periodic antibiotic susceptibility testing be
performed by a reference laboratory in the region. Note: WHO does not
recommend mass prophylaxis or prophylaxis of family members as a control
measure for shigellosis.
Amebiasis and giardiasis
Treatment for amebiasis or giardiasis should not be considered unless
microscopic examination of fresh feces shows amebic or Giardia trophozoites,
or two different antibiotics given for shigellosis have not resulted in
clinical improvement.
Treatment guidelines for amebiasis are as follows:
-
Metronidazole
-
Children: 30 mg/kg/day for 5-10 days.
-
Adults: 750 mg/3 times/day for 5-10 days.
Treatment guidelines for giardiasis are as follows:
-
Metronidazole
-
Children: 15 mg/kg/day for 5 days.
-
Adults: 250 mg/3 times/day for 5 days.
References
-
United Nations High Commissioner for Refugees. Handbook for emergencies.
Geneva, 1982.
-
Cairncross S, Feachem RG. Environmental health engineering in the
tropics: an introductory text. New York: John Wiley & Sons Ltd.,
1983:28-33.
Selected Reading
World Health Organization. A manual for the treatment of acute diarrhoea.
Geneva: Diarrhoeal Diseases Control Programme, 3rd. ed., 1990.
CDC. Shigella dysenteriae Type 1 Guatemala, 1991. MMWR 1991;40:421,427-8.
Keusch GT, Bennish ML. Shigellosis: recent progress, persisting problems and
research issues. Pediatr Infect Dis J 1989;8:713-9.
Smith M. Water and sanitation for disasters. Trop Doct 1991;21(suppl 1):30-7.
World Health Organization. Guidelines for cholera control. 1991;80.4;Rev. 2.
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