title: In vitro activities of carbapenem/sulbactam combination, colistin, colistin/rifampicin combination and tigecycline against carbapenem-resistant Acinetobacter baumannii.
abstract: OBJECTIVE
  To determine the in vitro activities and interactions of imipenem, colistin and tigecycline with old antibacterial agents against carbapenem-resistant Acinetobacter baumannii.
  
  
  METHODS
  Forty-three carbapenem-resistant A. baumannii isolates from the intensive care unit of a university hospital were collected and their MICs of imipenem, colistin and tigecycline were determined. With eight randomly selected carbapenem-resistant isolates, an in vitro time-kill study was performed for the evaluation of antibacterial activity of colistin, tigecycline, imipenem/sulbactam and colistin/rifampicin.
  
  
  RESULTS
  The time-kill study of colistin demonstrated bactericidal activity against A. baumannii at concentrations of 4xMIC and 8xMIC, whereas tigecycline showed bacteriostatic activity at all concentrations. The combination regimens of imipenem/sulbactam and colistin/rifampicin were synergistic and bactericidal at 1xMIC.
  
  
  CONCLUSIONS
  Imipenem/sulbactam combination, colistin and tigecycline showed good in vitro activities against carbapenem-resistant A. baumannii isolates. Even though colistin is bactericidal against carbapenem-resistant A. baumannii, the colistin/rifampicin combination is more warranted in order to be certain.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, Korea University, Seoul, Republic of Korea.
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Song
authors.forename: Sae Yoon
authors.initials: SY
authors.lastname: Kee
authors.forename: In Sook
authors.initials: IS
authors.lastname: Hwang
authors.forename: Yu Bin
authors.initials: YB
authors.lastname: Seo
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jeong
authors.forename: Woo Joo
authors.initials: WJ
authors.lastname: Kim
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Cheong
mesh_terms: D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D003091:Colistin / Q000494:pharmacology*; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012293:Rifampin / Q000494:pharmacology*; D013407:Sulbactam / Q000494:pharmacology*; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D000078304:Tigecycline; D008911:Minocycline; D013407:Sulbactam; D012293:Rifampin; D003091:Colistin