Fatality due to shigellosis with special reference to molecular analysis of Shigella sonnei strains isolated from the fatal cases

Background: Shigellosis as a global human health problem is more severe than other forms of gastroenteritis and causes over a million deaths in developing countries worldwide annually. Fatality due to shigellosis is usually due to dehydration and two-third of fatalities are seen among children. The aim of current study was to describe fatal cases of shigellosis due to infection with Shigella sonnei and S. flexneri. Patients and methods: We investigated the fatal cases of shigellosis among all children with acute diarrhea admitted to Children’s Medical Center, Tehran, Iran. Bacterial isolation and identification was achieved according to standard bacteriological methods. Antibiotic susceptibility tests, plasmid profiling and ribotyping were performed to investigate the clonal relationship among the isolates. Results: Among 1200 children with acute diarrhea, 140(12.7%) cases had shigellosis. Of these, three patients died. No signs of severe dehydration were observed among the fatal cases. The symptoms were not improved following antibiotic therapy and all three cases died after 24 h of hospitalization despite receiving intensive treatments. Stool cultures yielded S. flexneri and S. sonnei for one and two cases, respectively. The isolates were resistant to streptomycin, ampicillin, and sulfamethoxazole-trimethoprim. S. sonnei strains were further studied and showed a single pattern of antibiotic susceptibility and ribotyping. Conclusion: Mortality due to species other than S. dysenteriae is rare, however, in current study we found S. sonnei and S. flexneri as the cause of fatality among pediatric patients during the study.