title: Conventional and molecular investigation of Shigella isolates in relation to an outbreak in the area of Isfahan, Iran.
abstract: OBJECTIVE
  Over 165 million cases of shigellosis occur in the world each year, mostly in developing countries. Outbreaks of shigellosis are associated with poor sanitation, natural calamities, contaminated food and crowded living conditions. In late summer 2006, during the final stage of an outbreak of shigellosis at a vast region of Isfahan province, Naein & Ardestan, our laboratory was assigned to investigate the outbreak in order to determine the causative agent.
  
  
  METHODS
  A total of 146 rectal swabs which had been collected from the patients by local laboratories on separate days were screened using a battery of conventional and molecular tests.
  
  
  RESULTS
  Thirteen specimens tested positive for Shigella spp. They were identified as S. sonnei (6, 46.1%), S. dysenteriae (4, 30.8%), S. flexneri (2, 15.4%) and Shigella spp (1, 7.7%) by conventional and molecular microbiological tests. According to ribotyping results the isolates were grouped into 3 distinct clusters encompassing the majority of isolates and a single line of descent representing isolate S122 which was nonreactive with any Shigella polyvalent antisera.
  
  
  CONCLUSIONS
  This diarrheal outbreak appeared to be the result of shigellosis. Despite the fact that Shigella sonnei was the predominant organism isolated from patients, the causative agent of outbreak diarrhea remains obscure, since other Shigella species were also involved. The serologic testing supports this conclusion, as do the molecular patterns of the Shigella isolates. Having considered the time of investigation which was in the late stage of the outbreak, it was very likely that a collection of endemic and epidemic clinical samples was screened resulting in isolation of various Shigella species.
authors.affiliation: Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Dibaj
authors.affiliation: Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Aslani
authors.affiliation: Department of Microbiology, Alborz University of Medical Sciences, Karaj, Iran.
authors.forename: Parvin
authors.initials: P
authors.lastname: Heidarieh
authors.affiliation: Department of Epidemiology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Abdolrazagh
authors.initials: A
authors.lastname: Hashemi
authors.affiliation: Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Behrooz
authors.initials: B
authors.lastname: Ataei
authors.affiliation: Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Daei-Naser
authors.affiliation: Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Shojaei
keywords: Outbreak; Ribotyping; Shigella
references.citation: Trans R Soc Trop Med Hyg. 1982;76(2):164-8
references.pmid: 7101400
references.citation: Am J Public Health. 1995 Jun;85(6):812-6
references.pmid: 7762715
references.citation: Kansenshogaku Zasshi. 1998 Jun;72(6):615-20
references.pmid: 9695472
references.citation: Epidemiol Infect. 2013 Feb;141(2):233-41
references.pmid: 22361246
references.citation: Can J Infect Dis Med Microbiol. 2009 Fall;20(3):e56-62
references.pmid: 20808457
references.citation: J Clin Microbiol. 2006 Aug;44(8):2879-83
references.pmid: 16891506
references.citation: Res Microbiol. 2001 Jan-Feb;152(1):47-55
references.pmid: 11281325
references.citation: Emerg Infect Dis. 2010 Nov;16(11):1718-23
references.pmid: 21029529
references.citation: Res Microbiol. 1997 Nov;148(8):649-59
references.pmid: 9765850
references.citation: South Med J. 2012 Jan;105(1):1-4
references.pmid: 22189658
references.citation: J Microbiol. 2005 Apr;43(2):133-43
references.pmid: 15880088
references.citation: Epidemiol Infect. 1996 Apr;116(2):127-35
references.pmid: 8620903
references.citation: J Infect Dev Ctries. 2009 Nov 27;3(11):817-42
references.pmid: 20061678
references.citation: Ann Inst Pasteur Microbiol. 1986 Sep-Oct;137B(2):165-75
references.pmid: 2446639
references.citation: Curr Opin Infect Dis. 2010 Oct;23(5):475-80
references.pmid: 20689423