title: Distribution of pathogenicity island (PAI) markers and phylogenetic groups in diarrheagenic and commensalEscherichia colifrom young children.
abstract: OBJECTIVE
  This case-control study investigated the various PAI markers, phylogenetic groups and antimicrobial susceptibility among DEC and commensalE. coliisolates.
  
  
  BACKGROUND
  DiarrheagenicEscherichia coli(DEC) is an emerging agent among pathogens that cause diarrheal diseases and represents a major public health problem in developing countries. The major difference in virulence among DEC pathotype and commensals may be related to the presence of specific genomic segments, termed pathogenicity islands (PAIs).
  
  
  METHODS
  A total of 600 stool specimens from children (450 with and 150 without diarrhea) were collected and various PAI markers, phylogenetic groups and antimicrobial resistance profile among DEC and commensalE. coliisolates were detected.
  
  
  RESULTS
  One hundred sixty eight (90.3%) isolates were resistant to one or more antimicrobial agents. PAI markers were detected in a substantial percentage of commensal (90%) and DEC isolates (99.3%) (P> 0.05). The most prevalent PAI marker among DEC and commensal isolates was HPI (91.9% DEC vs. 68% commensal). We found a high number of PAI markers such as SHI-2, Sheand LEE that were significantly associated with DEC. Several different combinations of PAIs were found among DEC isolates. Comparison of PAIs among DEC and commensal isolates showed that many DEC isolates (94.8%) carried two or more PAI markers, while 76% of commensals had only one PAI marker (P<0.05). According to the phylogenetic classification, group B2 was the most commonly found in the DEC isolates. Furthermore, our results showed that group B2 can be present in commensal isolates (18%).
  
  
  CONCLUSIONS
  These results indicate that PAI markers are widespread among commensal and DEC isolates and these commensal isolates may be reservoirs for transmission of these markers.
authors.affiliation: Department of Microbiology, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Ghazal
authors.initials: G
authors.lastname: Naderi
authors.affiliation: Department of Microbiology, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Fakhri
authors.initials: F
authors.lastname: Haghi
authors.affiliation: Department of Microbiology, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Habib
authors.initials: H
authors.lastname: Zeighami
authors.affiliation: Department of Microbiology, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Hemati
authors.affiliation: Department of Microbiology, Zanjan Islamic Azad University, Zanjan, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Masoumian
keywords: Child; Developing countries; Diarrhea; Escherichia coli; Pathogenicity Island