Shigellosis is diagnosed directly by stool culture. STEC/EHEC infection is diagnosed by simultaneous culture (assaying for E. coli strains that do not ferment sorbitol, with subsequent serotyping for O157) and assay for the detection of Shiga toxin (which can rapidly detect non-O157 STEC/EHEC and sorbitol-fermenting strains of O157:H7).
Treatment: Shigellosis and Infection with STEC/EHEC - In the United States, because of the ready transmissibility of Shigella, antibiotics are recommended. Fluoroquinolones (e.g., ciprofloxacin, 500 mg bid) are effective, as are ceftriaxone, azithromycin, pivmecillinam, and some fifth-generation quinolones.
- - S. dysenteriae infection should be treated for 5 days and non-dysenteriae Shigella infection for 3 days.
- - Immunocompromised pts should receive 7-10 days of treatment.
- Antibiotic treatment for STEC/EHEC infections should be avoided, since antibiotics may increase the incidence of HUS.
- Rehydration usually is not needed; Shigella infection rarely causes significant dehydration. If required, rehydration should be oral, and nutrition should be started as soon as possible. Use of antimotility agents may prolong fever and increase the risk of HUS and toxic megacolon.
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