title: Comparative in vitro activity of carbapenems against clinical isolates of Acinetobacter baumannii.
abstract: OBJECTIVE
  The aim of this multi-hospital study was to assess the in vitro activity of doripenem and its comparators, imipenem and meropenem, using the new CLSI breakpoints against a large population of a frequently isolated nosocomial pathogen, Acinetobacter baumannii.
  
  
  RESULTS
  During a 2-year period, four referral or tertiary hospitals submitted 400 isolates of Ac. baumannii for susceptibility testing using imipenem, meropenem and doripenem via disc diffusion and E-test methods. A subset of 390 isolates was resistant to all three tested carbapenems. Doripenem and meropenem (MIC50 , 32 μg ml(-1) ) had comparable activity, albeit doripenem's activity was greater than imipenem (MIC50 , >32 μg ml(-1) ). A significantly higher proportion of the isolates were inhibited by doripenem than by imipenem at MIC values of 12, 16, 24 and 32 μg ml(-1) (P < 0·05). The cumulative percentage of imipenem MICs was lower compared to its comparators. The comparison of resistance rate to imipenem and meropenem based on old and new breakpoints showed <1% difference. The overall agreement between the two susceptibility testing methods was ≥95%.
  
  
  CONCLUSIONS
  Doripenem has a slightly greater in vitro activity than imipenem in terms of zone breakpoints and MIC values, but its activity is comparable to meropenem.
  
  
  CONCLUSIONS
  Doripenem should be considered as a therapeutic option for monotherapy or combination therapy, particularly when the therapeutic options are limited.
authors.affiliation: Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.|Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Douraghi
authors.affiliation: Department of Microbiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Z
authors.initials: Z
authors.lastname: Ghalavand
authors.affiliation: Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Nateghi Rostami
authors.affiliation: Department of Epidemiology and Biostatistics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: H
authors.initials: H
authors.lastname: Zeraati
authors.affiliation: Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Aliramezani
authors.affiliation: Department of Microbiology, Reference Health Laboratories, Ministry of Health, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Rahbar
authors.affiliation: Pediatrics Infectious Diseases Research Center, Department of Infectious Diseases, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Mohammadzadeh
authors.affiliation: Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Ghourchian
authors.affiliation: Department of Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: M A
authors.initials: MA
authors.lastname: Boroumand
authors.affiliation: Department of Pathology, Imam Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Abdollahi
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D000077726:Doripenem; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007492:Iran / Q000453:epidemiology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013845:Thienamycins / Q000494:pharmacology*; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D013845:Thienamycins; D015378:Imipenem; D000077726:Doripenem; D000077731:Meropenem
keywords: Acinetobacter baumannii; E-test; disc diffusion; doripenem; imipenem; meropenem