Treatment and Prevention and Control of Shigella Infections

Treatment

Uncomplicated shigellosis is a self-limited condition and patients usually recover spontaneously in a few days. Hence, no antibiotics are recommended for these cases. The dehydra-tion observed in acute cases, particularly in infants and young children, needs adequate replacement of fluids and electrolytes by oral fluid and salts. Antibiotic treatment for Shigella infec-tion is recommended (i) for severe or toxic cases and (ii) for the very young, debilitated, and the aged individuals. Antibiotic treatment is recommended to decrease the duration of illness, person-to-person spread, and cases in household contacts.

In developing countries, treatment in malnourished children is likely to reduce the risk of worsening malnutrition morbidity following shigellosis. Prophylactic antibiotics are not recom-mended for contacts.

Trimethoprim–sulfamethoxazole, ampicillin, tetracycline, and the quinolones, such as nalidixic acid and ciprofloxacin, are frequently used antibiotics. Trimethoprim–sulfamethox-azole is very effective for shigellosis. The antibiotics act against Shigella by producing a sequential blockade in folic acid synthesis. This is the drug of choice when antibiotics susceptibility of the bacteria is not known. However, ampicil-lin is still the drug of choice if Shigella isolate is susceptible to this drug.

Antibiotics-resistant Shigella: Multiple-antibiotics-resistantplasmids are widely prevalent in shigellae and were first docu-mented in Japan during early 1950s. Most of these strains were resistant to streptomycin, chloramphenicol, and sulfonamides. Indiscriminate use of the antibiotics has worsened the prob-lem. Hence, it is essential to treat the cases of shigellosis with the results of in vitro antibiotic susceptibility testing of Shigella.

Prevention and Control

In developed countries, person-to-person transmission is the most common source of infection. Water contaminated with human excreta is the most common source of infection. Therefore, control consists essentially in improving personal and environmental sanitation. Antibiotics are not used in pro-phylaxis. No effective vaccine is available.