Effectiveness of antibiotic combination therapy as evaluated by the Break-point Checkerboard Plate method for multidrug-resistant Pseudomonas aeruginosa in clinical use.
Multidrug-resistant Pseudomonas aeruginosa (MDRP) strains are defined as having resistance to the following 3 groups of antibiotics: carbapenems, aminoglycosides, and fluoroquinolones. Antibiotic combinations have demonstrated increased activity in vitro compared with a single agent. As an in vitro method of determining the combination activity of antibiotics, the Break-point Checkerboard Plate (BC-plate) can be used routinely in clinical microbiology laboratories. We evaluated the effectiveness of the BC-plate for MDRP infections in clinical settings. We retrospectively selected cases of MDRP infection treated with combination therapy of antibiotics in Tokyo Medical University Hospital (1015 beds), Tokyo, Japan, from November 2010 to October 2012. A total of 28 MDRP strains were clinically isolated from 28 patients during the study period. This study design is a case series of MDRP infection. Six infections among the 28 patients were treated based on the results of the BC-plate assay, and the 6 strains tested positive for MBL. One patient had pneumonia, 3 had urinary tract infections, 1 had vertebral osteomyelitis, and 1 had nasal abscess. The combination of aztreonam with amikacin demonstrated the most frequently recognized in vitro effect (5 patients). Next, aztreonam with ciprofloxacin and piperacillin with amikacin revealed equivalent in vitro effects (3 patients, respectively). The clinical cure rate was 83.3% (5/6 patients). Antibiotic combination therapy based on the results of the BC-plate assay might indicate the effective therapy against MDRP infection in clinical settings.
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan.
Itaru
I
Nakamura
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan; Department of Microbiology, Tokyo Medical University, Japan. Electronic address: t_yama@tokyo-med.ac.jp.
Tetsuo
T
Yamaguchi
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan.
Ayaka
A
Tsukimori
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan.
Akihiro
A
Sato
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan.
Shinji
S
Fukushima
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan.
Yasutaka
Y
Mizuno
Department of Infection Control and Prevention, Tokyo Medical University Hospital, Japan; Department of Microbiology, Tokyo Medical University, Japan.
Tetsuya
T
Matsumoto
D000583:Amikacin / Q000008:administration & dosage; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001398:Aztreonam / Q000008:administration & dosage; D002939:Ciprofloxacin / Q000008:administration & dosage; D024901:Drug Resistance, Multiple, Bacterial; D004359:Drug Therapy, Combination; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D010878:Piperacillin / Q000008:administration & dosage; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D012189:Retrospective Studies
D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D000583:Amikacin; D001398:Aztreonam; D010878:Piperacillin
Antibiotic combination therapy; BC-Plate; MB; MDRP; Pseudomonas aeruginosa