Shigellosis in Calcutta during 1990-1992: antibiotic susceptibility pattern and clinical features.

Of 230 cases of bloody diarrhoea studied, 100 (43.5%) were positive for Shigellae by stool culture, of which Shigella dysenteriae type 1 was isolated from 56 cases, S. flexneri from 35, S. boydii from 5 and S. sonnei from 4. The major clinical manifestations of the patients infected with Shigella spp. were abdominal pain, anorexia, vomiting, tenesmus, and fever. Fever of above 100.5 degrees F and frequency of stool of more than 15 per day were noticed more among cases infected with S. dysenteriae type 1 and S. flexneri. Vomiting was more frequently observed in cases infected with S. sonnei or S. boydii (44.4%) as compared to those infected with S. dysenteriae type 1 (10.7%) and S. flexneri (8.6%). All Shigella isolates were uniformly susceptible to norfloxacin and ciprofloxacin but were resistant to streptomycin. S. dysenteriae type 1 isolates were susceptible to nalidixic acid (69.6%), ampicillin (5.4%), TMP-SMX (12.5%), furazolidone (98.2%) and gentamycin (80.4%), whereas all other Shigella isolates (S. flexneri, S. boydii, and S. sonnei) were uniformly susceptible to nalidixic acid, > 94% susceptible to furazolidone, and only moderately susceptible to ampicillin (28.6% to 55.5%) and TMP-SMX (22.2% to 48.6%).