title: The occurrence of extended-spectrum β-lactamase producing Shigella spp. in Tehran, Iran.
abstract: OBJECTIVE
  The emergence of extended-spectrum β-lactamase (ESBL)-producing Shigella spp. is of increasing clinical concern specially in children worldwide. The aim of this study was to investigate the occurrence of extended-spectrum β-lactamase producing Shigella spp. in Tehran, Iran.
  
  
  METHODS
  The study included all Shigella isolates recovered from pediatric patients aged less than 12 years admitted to a major pediatric hospital in Tehran, Iran, from 2008 to 2010. Bacterial identification, antimicrobial susceptibility testing, extended spectrum β-lactamases (ESBLs) screening and confirmatory tests were performed according to the standard guidelines. Conjugal transfer experiments and plasmid analysis were also carried out. Polymerase chain reaction and sequencing were used to identify the genetic determinants responsible for ESBL production.
  
  
  RESULTS
  Four out of 55 Shigella isolates, including three S. sonnei and one S. flexneri, showed an ESBL-positive phenotype. Plasmid transfer of the ESBL phenotype was successful for the S. flexneri isolate only. By PCR and sequencing, one S. sonnei isolate tested positive for the CMY-59 gene, while the other two S. sonnei and the S. flexneri isolates tested positive for the bla TEM-1 and bla CTX-M-15 genes.
  
  
  CONCLUSIONS
  We found the prevalence of ESBL producing Shigella isolates was higher than detection rates observed in many other countries. Our finding raise concerns about the dissemination of ESBL among the strains of endemic S. sonnei throughout the country, because this species is now the most frequently isolated Shigella species in Iran and shigellosis by such strains in the community can pose a significant threat to patients and presents a challenge for disease management.
authors.affiliation: Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Ranjbar
authors.forename: Farzaneh Mirsaeed
authors.initials: FM
authors.lastname: Ghazi
authors.forename: Shohreh
authors.initials: S
authors.lastname: Farshad
authors.forename: Giovanni Maurizio
authors.initials: GM
authors.lastname: Giammanco
authors.forename: Aurora
authors.initials: A
authors.lastname: Aleo
authors.forename: Parviz
authors.initials: P
authors.lastname: Owlia
authors.forename: Nematollah
authors.initials: N
authors.lastname: Jonaidi
authors.forename: Nourkhoda
authors.initials: N
authors.lastname: Sadeghifard
authors.forename: Caterina
authors.initials: C
authors.lastname: Mammina
keywords: Antibiotic resistance; ESBLs; Shigella spp