title: In vitro combination effects of aztreonam and aminoglycoside against multidrug-resistant Pseudomonas aeruginosa in Japan.
abstract: The aim of this study was to evaluate the in vitro combination effects of  aztreonam (AZT) and aminoglycosides against multidrug-resistant (MDR) Pseudomonas aeruginosa  strains in Japan. We investigated 47 MDR P. aeruginosa strains collected from 8 facilities. We  selected the aminoglycosides amikacin (AMK), gentamicin (GM), and arbekacin (ABK) to examine their  effects when combined with AZT using the checkerboard method. Of the 47 MDR P. aeruginosa strains,  41 tested positive for metallo-β-lactamase (MBL). In all combinations, aminoglycosides decreased  the minimum inhibitory concentrations of AZT in a dose-dependent manner, and there was no apparent  antagonism. The combination effects were scored on a scale of 0 to 4, and statistical analysis was  performed using the Wilcoxon signed-rank test. In all 47 strains, AZT + ABK (mean score, 2.02) had  the highest score, followed by AZT + AMK (1.68) and AZT + GM (1.38) (ABK versus GM, P < 0.0001). In  41 MBL-positive strains, AZT + ABK (mean score, 2.05) had the highest score, followed by AZT + AMK  (1.56) and AZT + GM (1.37) (ABK versus AMK, P = 0.02, and ABK versus GM, P < 0.0001). AZT + ABK was  the most promising combination regimen against MDR P. aeruginosa strains; the other promising  combinations were AZT + AMK and AZT + GM.
authors.affiliation: Department of Infectious Diseases, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo, Japan. h-araoka＠toranomon.gr.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Araoka
authors.forename: Masaru
authors.initials: M
authors.lastname: Baba
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tateda
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ishii
authors.forename: Toyoko
authors.initials: T
authors.lastname: Oguri
authors.forename: Katsuko
authors.initials: K
authors.lastname: Okuzumi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Oishi
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Mori
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Mitsuda
authors.forename: Kyoji
authors.initials: K
authors.lastname: Moriya
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nakamori
authors.forename: Norio
authors.initials: N
authors.lastname: Ohmagari
authors.forename: Keizo
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoneyama
mesh_terms: D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001398:Aztreonam / Q000494:pharmacology*; D003982:Dibekacin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004353:Drug Evaluation, Preclinical; D024901:Drug Resistance, Multiple, Bacterial; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D018709:Statistics, Nonparametric
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D005839:Gentamicins; D003982:Dibekacin; D000583:Amikacin; D001398:Aztreonam; C031986:arbekacin