title: In vitro synergy of colistin combinations against extensively drug-resistant Acinetobacter baumannii producing OXA-23 carbapenemase.
abstract: Fifty extensively drug-resistant Acinetobacter baumannii (XDRAB) were isolated from patients. The chequerboard microdilution method was used to determine the in vitro activities of five colistin (COL)-based combinations including COL+fosfomycin (FOS), COL+rifampicin (RIF), COL+imipenem (IMP), COL+sulbactam (SUP) and COL+levofloxacin (LVX). The synergistic activity was evaluated by the fractional inhibitory concentration index (FICI). According to our results, the combination of COL was synergistic with FOS, RIF, IMP, SUP and LVX with the ratios of 50, 72, 88, 92 and 64%, respectively. When combined with COL, the other five agents showed increased antimicrobial activities. In addition, two of the combinations, COL+RIF and COL+IMP, were more active than the combinations of COL+FOS, COL+SUP and COL+LVX. More importantly, these combination regimens could exert synergistic effects at the sub-minimum inhibitory concentration (MIC) levels against XDRAB strains.
authors.affiliation: a Department of Infectious Diseases , the First Affiliated Hospital of Anhui Medical University , Hefei , China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Wei
authors.affiliation: a Department of Infectious Diseases , the First Affiliated Hospital of Anhui Medical University , Hefei , China.
authors.forename: Haifei
authors.initials: H
authors.lastname: Yang
authors.affiliation: a Department of Infectious Diseases , the First Affiliated Hospital of Anhui Medical University , Hefei , China.|b Institute of Bacterium Resistance , Anhui Medical University , Hefei , China.|c Anhui Center for Surveillance of Bacterial Resistance , Hefei , China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: a Department of Infectious Diseases , the First Affiliated Hospital of Anhui Medical University , Hefei , China.|b Institute of Bacterium Resistance , Anhui Medical University , Hefei , China.|c Anhui Center for Surveillance of Bacterial Resistance , Hefei , China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ye
authors.affiliation: a Department of Infectious Diseases , the First Affiliated Hospital of Anhui Medical University , Hefei , China.|b Institute of Bacterium Resistance , Anhui Medical University , Hefei , China.|c Anhui Center for Surveillance of Bacterial Resistance , Hefei , China.
authors.forename: Jiabin
authors.initials: J
authors.lastname: Li
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001426:Bacterial Proteins / Q000096:biosynthesis; D003091:Colistin / Q000008:administration & dosage*; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005578:Fosfomycin / Q000008:administration & dosage; D006801:Humans; D015378:Imipenem / Q000008:administration & dosage; D066298:In Vitro Techniques; D064704:Levofloxacin / Q000008:administration & dosage; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012293:Rifampin / Q000008:administration & dosage; D013407:Sulbactam / Q000008:administration & dosage; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D005578:Fosfomycin; D064704:Levofloxacin; D015378:Imipenem; C466679:beta-lactamase OXA-23; D001618:beta-Lactamases; C063912:carbapenemase; D013407:Sulbactam; D012293:Rifampin; D003091:Colistin
keywords: Acinetobacter; Antimicrobial resistance; Combination therapy; Susceptibility; Synergy