title: Widespread antibiotic resistance of diarrheagenic Escherichia coli and Shigella species.
abstract: BACKGROUND
  Antibiotic resistance of enteric pathogens particularly Shigella species, is a critical world-wide problem and monitoring their resistant pattern is essential, because the choice of antibiotics is absolutely dependent on regional antibiotic susceptibility patterns. During summer 2013, an unusual increase in number of diarrheal diseases was noticed in Isfahan, a central province of Iran. Therefore, the antibiotic resistance of diarrheagenic Escherichia coli and Shigella species isolated were evaluated.
  
  
  METHODS
  According to the guideline on National Surveillance System for Foodborn Diseases, random samples from patients with acute diarrhea were examined in local laboratories of health centers and samples suspicious of Shigella spp. were further assessed in referral laboratory. Isolated pathogens were identified by standard biochemical and serologic tests and antibiotic susceptibility testing was carried out by disc diffusion method.
  
  
  RESULTS
  A total of 1086 specimens were obtained and 58 samples suspicious of Shigella were specifically evaluated. The most prevalent isolated pathogen was Shigella sonnei (26/58) followed by E. coli (25/58) and Shigella flexneri (3/58). A large number of isolated bacteria were resistant to co-trimoxazole (Shigella spp: 100%, E. coli: 80%), azithromycin (Shigella spp: 70.4%, E. coli: 44.0%), ceftriaxone (Shigella spp: 88.9%, E. coli: 56.0%) and cefixime (Shigella spp: 85.2%, E. coli: 68.0%). About88.3% of S. sonnei isolates, one S. flexneri isolate, and 56% of E. coli strains were resistant to at least three antibiotic classes (multidrug resistant).
  
  
  CONCLUSIONS
  Due to high levels of resistance to recommended and commonly used antibiotics for diarrhea, continuous monitoring of antibiotic resistance seems essential for determining best options of empirical therapy.
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Azam Fatahi
authors.initials: AF
authors.lastname: Sadeghabadi
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Ajami
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Fadaei
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Zandieh
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Heidari
authors.affiliation: Isfahan Provincial Health Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Sadeghi
authors.affiliation: Nosocomial Infection 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: Shervin Ghaffari
authors.initials: SG
authors.lastname: Hoseini
keywords: Antibiotic resistance; Escherichia coli; Iran; Shigella; diarrhea