title: Multidrug resistance among Acinetobacter baumannii isolates from Iran: changes in antimicrobial susceptibility patterns and genotypic profile.
abstract: OBJECTIVE
  Widespread multidrug-resistant Acinetobacter baumannii (MDR-AB) strains have limited therapeutic options for treating intensive care unit (ICU) patients with MDR-AB infection in Iran. We aimed to evaluate MDR-AB diversity and antimicrobial susceptibility in Tehran (Iran) to address the need for feasible and effective control approaches against severe MDR-AB infections.
  
  
  METHODS
  We used amplified fragment length polymorphism (AFLP) and minimum inhibitory concentration (MIC) determinations to compare genotypic diversity and susceptibility patterns of 100 MDR-AB isolates from ICU patients in two medical centers in Tehran (Iran), from 2006 to 2011.
  
  
  RESULTS
  Within 5 years, drastic genotypic changes occurred among MDR-AB isolates, and resistance to antimicrobials increased 0-30%. In 2011, 6-100% of isolates were resistant to every agent tested. All isolates remained susceptible to either minocycline or tobramycin, however, MIC50 concentrations against these agents increased. Novel international clone (IC) variants (not IC I-III types) comprised 36% MDR-AB isolates in 2011.
  
  
  CONCLUSIONS
  The MDR-AB population in Tehran is rapidly changing toward growing resistance to various antimicrobials, including colistin and tigecycline. Although increasing resistance to last-resort antimicrobials is alarming, simultaneous susceptibility of all MDR-AB isolates to some conventional antibiotics highlights the merits of investigating their synergistic activity against extended-spectrum and pandrug resistant A. baumannii. Integrating the novel Iranian MDR-AB IC variants into epidemiologic clonal and susceptibility profile databases can help global efforts toward the control of MDR-AB pandemic.
authors.affiliation: 1 Department of Microbiology, School of Medicine, Tehran University of Medical Sciences , Tehran, Iran .
authors.forename: Abbas
authors.initials: A
authors.lastname: Bahador
authors.forename: Reza
authors.initials: R
authors.lastname: Raoofian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taheri
authors.forename: Babak
authors.initials: B
authors.lastname: Pourakbari
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hashemizadeh
authors.forename: Farhad B
authors.initials: FB
authors.lastname: Hashemi
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004357:Drug Synergism; D005838:Genotype; D006801:Humans; D007492:Iran; D008826:Microbial Sensitivity Tests / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents