Jpn. J. Infect. Dis., 65 (1), 84-87, 2012
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Hideki Araoka1*, Masaru Baba1, Kazuhiro Tateda2, Yoshikazu Ishii2, Toyoko Oguri3, Katsuko Okuzumi4, Tsuyoshi Oishi5, Shinichiro Mori6, Toshihiro Mitsuda7, Kyoji Moriya8, Yoshitaka Nakamori9, Norio Ohmagari10, Keizo Yamaguchi2, Akiko Yoneyama1, and ABX Combination Therapy Study Group
1Department of Infectious Diseases, Toranomon Hospital, Tokyo 105-8470; 2Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo 143-8540; 3Laboratory Medicine, Kameda Medical Center, Chiba 296-8602; 4Department of Medical Safety Administration Division of Infection Control Dokkyo Medical University Hospital, Tochigi 321-0293; 5Department of Infectious Diseases, Tokyo Medical University Ibaraki Medical Center, Ibaraki 300-0395; 6Hematopoietic Stem Cell Transplantation Unit, National Cancer Center Hospital, Tokyo 104-0045; 7Department of Infection Prevention and Control, Yokohama City University Hospital, Kanagawa 236-0004; 8Department of Infection Control and Prevention, Graduate School of Medicine Faculty of Medicine, The University of Tokyo, Tokyo 113-0033; 9Department of Respiratory Diseases, Misyuku Hospital, Tokyo 153-0051; and 10Division of Infectious Diseases, Shizuoka Cancer Center, Shizuoka 411-8777, Japan
(Received August 8, 2011. Accepted November 8, 2011)
*Corresponding author: Mailing address: Department of Infectious Diseases, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo 105-8470, Japan. Tel: +81-3-3588-1111, Fax: +81-3-3582-7068, E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
SUMMARY: 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.