Shigella Species and Serotypes among Clinical Isolates in Thailand from 2001 to 2005
Chaiwat Pulsrikarn DVM*, Aroon Bangtrakulnonth BSc*, Srirat Pornruangwong MSc*, Thayat Sriyapai MSc*, Pathom Sawanpanyalert MD, DrPH**, Nalinee Aswapokee MD***, Wichai Techasathit MD****
Affiliation : * WHO National Salmonella and Shigella Center, National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand ** National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand *** Unit of Infectious Diseases, Faculty of Internal Medicine, Siriraj University Hospital, Mahidol University, Bangkok, Thailand **** Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To study the species and the serotypes of the clinical isolates of Shigella obtained from patients in
Thailand
Material and Method: The World Health Organization National Salmonella and Shigella Center, Thailand,
had confirmed the species and performed serotype identification of 1,913 clinical isolates of Shigella
collected from the laboratory network of Department of Medical Sciences and the collaborated hospitals
across Thailand from 2001 to 2005.
Results : Between the year 2001 and 2005, 728, 481, 160, 247, 297 clinical isolates were tested, respectively.
There were 5 isolates of S. dysenteriae (group A), 416 isolates of S. flexneri (group B), 4 isolates of S. boydii
(group C) and 1,488 isolates of S. sonnei (group D). A total of 21 Shigella serotypes were identified and there
were 3 serotypes in group A, 11 serotypes in group B, 4 serotypes in group C, and 3 serotypes in group D.
Throughout these five years, the five common serotypes were S. sonnei Phases I and II, 28.6% (548 isolates);
S. sonnei Phase I, 24.6% (470 isolates); S. sonnei Phase II, 24.6% (470 isolates); S. flexneri Type 2a, 10.9%
(208 isolates), and S. flexneri Type 3a, 6.3% (121 isolates), respectively.
Conclusion : At the national scale in Thailand from 2001 to 2005, S. sonnei was the most frequent Shigella spp.
isolated from patients in Thailand. In addition, S. dysenteriae and S. boydii were extremely uncommon. These
findings are important in future vaccine development.
Keywords : Serotyping, Shigella, Shigella sonnei, Thailand
