In certain patients with bacillary dysentery (particularly in infants and older adults), significant dehydration may result from excessive fluid loss through diarrhea and vomiting. The fluid losses can generally be replaced by oral intake because the diarrhea associated with bacillary dysentery is not normally associated with profound fluid and electrolyte depletion. If vomiting or extreme toxemia is a prominent feature of the illness, especially in the very young or very old, intravenous fluid replacement may be necessary. As in all diarrheal illnesses, fluid repletion is the mainstay of therapy and should be given even as antimicrobial therapies are being considered.
Antibiotics are useful in the management of shigellosis and may be lifesaving in the case of Shiga dysentery. Because the infection is normally self-limited and because antibiotic resistance commonly develops in populations after prolonged use of drugs, some experts and the Centers for Disease Control and Prevention (CDC) recommend that antimicrobial therapy be reserved for the most severely ill patients—those with immunosuppression, with bacteremia, or with complications and those who are hospitalized; for food handlers, residents of nursing homes, or childcare providers; or for situations in which spreading and outbreaks are possible. However, because the infection is generally transmitted from person to person and the infected or colonized person represents the major reservoir of infection, for public health reasons individuals with a positive stool culture or with known bacillary dysentery who are living or working in facilities with high risk for transmission (daycare centers, nursing homes) should be treated.
Because of the emergence of drug resistance, the efficacy of fluoroquinolones, trimethoprim-sulfamethoxazole, and macrolides in adults as empirical therapy when susceptibility is unknown has diminished. Risk factors for antimicrobial resistance include foreign travel, particularly to Southeast Asia and Africa; men who have sex with men; and HIV coinfection. For persons without these risk factors, a fluoroquinolone remains the drug of choice; for persons with these risk factors, cefixime or ceftriaxone is a reasonable alternative. For cases in which susceptibility is known,Trimethoprim-sulfamethoxazole had been the treatment of choice for this enteric infection, but resistance has become widespread for strains ofShigella. Although 3-day therapy is generally recommended in shigellosis, single-dose fluoroquinolones may be given for milder forms of shigellosis.For children, various drugs may be used. Cephalosporins have become a common form of treatment of pediatric shigellosis. Although not approved for use in children, short-course fluoroquinolones can be safely used Amdinocillin, an unlicensed drug, has been used in Bangladesh for shigellosis. Azithromycin has been used successfully for treatment of multidrug-resistantShigella infection in adults and should be useful in the management of pediatric shigellosis. Nalidixic acid may be helpful in the management of pediatric shigellosis.Rifaximin should not be used to treat shigellosis. However, it has been proven to prevent shigellosis in experimental challenge studies and is an option to prevent traveler's diarrhea, probably by eradicatingShigella infection before the organisms reach the colon and establish infection.