298 Letters 2. Schwartz B, Elliott JA, Butler JC, Simon PA, Jameson BL, Welch GE, Facklam RR: Clusters of invasive group A strep- tococcal infections in family, hospital, and nursing home set- tings. Clinical Infectious Diseases (1992) 15:277-284. 3. Bartlett JG, Mundy LM: Community-acquired pneumonia. New England Journal of Medicine (1995) 333:1618-1624. 4. Basiliere JL, Bistrong HW, Spence WF: Streptococcal pneu- monia: recent outbreaks in military recruit populations. American Journal of Medicine (1968) 44:580-589. 5. Centers for Disease Control: Nursing home outbreaks of in- vasive group A streptococcal infections - Illinois, Kansas, North Carolina, and Texas. Morbidity & Mortality Weekly Report (1990) 33:577-579. 6. McIntyre HD, Armstrong JG, Mitchell CA: Streptococcus pyogenes pneumonia with abscess formation (published erra- tum appears in Australian & New Zealand Journal of Medi- cine 1990, 20:753). Australian & New Zealand Journal of Medicine (1989) 19: 248-249. 7. Clementsen P, Milman N: Bilateral pulmonary abscesses caused by Streptococcus pyogenes: diagnostic importance of fiberoptic bronchoscopy. Scandinavian Journal of Infectious Diseases (1994) 26: 755-757. 8. McMurray JJ, Fraser DM, Brogan O: Fatal Streptococcus pyogenes pneumonia. Journal of the Royal Society of Medi- cine (1987) 80:525-526. 9. Brusch JL, Mark EJ: Case records of the Massachussetts General Hospital (case 13-1996). New England Journal of Medicine (1996) 334:1116-1123. 10. Ispahani P, Donald FE, Aveline AJD: Streptococcuspyogenes bacteremia: an old enemy subdued, but not defeated. Journal of Infection (1988) 16: 37-46. Serotypes and Antimicrobial Susceptibility Patterns of Shigella Species Isolated from Children in Calcutta, India Shigellosis in children is a major public health problem in developing countries. The disease is endemic throughout the developing world, where it causes ma- jor epidemics from time to time. The World Health Or- ganisation (WHO) has estimated that 3.5 million chil- dren die from diarrhoeal diseases each year, 600000 of them from shigellosis alone [1]. Although early anti- biotic treatment of dysentery has been recommended S. Dutta (N~) Division of Microbiology, National Institute of Cholera and Enteric Diseases P-33, C.I.T. Road, Scheme XM, Beliaghata, PO Box 177, Calcutta 700 010, India T. Sinha Mahapatra Department of Pediatric Medicine, Dr. B.C. Roy Memorial Hospital for Children 111, Narkeldanga Main Road, Calcutta 700 056, India P. Dutta, U. Mitra, S. Dasgupta Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme XM, Beliaghata, PO Box 177, Calcutta 700 010, India [1], multiple drug resistance among Shigella spp. in var- ious geographical regions [2, 3] presents a major threat in the control of shigellosis. The present study was designed to assess the impor- tance of Shigella as the sole aetiological agent of diar- rhoea, to study the distribution of Shigella spp. in Cal- cutta, India, and to observe the antimicrobial suscepti- bility patterns of isolated strains. Stool samples were collected from children < 5 years of age who attended the outpatient department of the Dr. B.C. Roy Memorial Hospital for Children in Calcutta. The first two children who presented Monday through Friday from May 1995 to December 1996 with acute diarrhoea and no history of prior antibiotic therapy were selected for the study. In this way, a total of 918 randomly selected stool samples were collected for the study regardless of stool character and disease severi- ty. Fresh stool samples were cultured for Shigella spp. us- ing selective media and were examined for the presence of established enteropathogens using standard tech- niques [4]. The Shigella strains identified were tested for antimicrobial susceptibility using the disc diffusion technique [5] and commercially available discs of anti- biotics commonly used to treat shigellosis. Escherichia coli ATCC 25922 was used as the quality reference strain. Minimal inhibitory concentrations (MIC) were also determined for the Shigella strains displaying re- duced susceptibility to the antimicrobial agents by an agar dilution technique [6]. Shigella spp. were isolated as the sole pathogen from 47 of 918 (5%) stool samples. The rate of isolation of Shi- gella from dysentery and watery diarrhoea cases was 11% and 2%, respectively. Mixed infections of Shigella and other enteropathogens were not observed in our study. Shigella flexneri was the predominant species iso- lated (24/47 cases; 51%) during the period of observa- tion. Serotype classification showed that Shigella flex- neri types 2 (10/24; 42%) and 3 (7/24; 29%) were the most common serotypes isolated. Shigella dysenteriae type 1 was isolated from only five samples (5/47; 10%). The ratio of isolation of Shigella dysenteriae type 1 to Shigella flexneri was 0.2 (5/24 cases). In 1984 the isolation rate of Shigella dysenteriae type 1 had increased to 30%; its isolation ratio with Shigella flexneri changed to 5 (34/7), which reflected an epi- demic of shigellosis occurring at that time. During the postepidemic period of 1985-1988, the isolation of Shi- gella dysenteriae type 1 decreased and that of Shigella flexneri increased, with a resultant ratio of 0.6 (27/41 cases) [7]. However, during 1990-1994, Shigella dysen- teriae type 1 was isolated more frequently, and the ratio changed to 1.6. (56/35) [8]. Serotype distribution of Shi- gella boydii (10/47 cases; 21% ), isolated during the peri-