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Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
Published on: April 18, 2019
'Break-point Checkerboard Plate' for screening of appropriate antibiotic combinations against multidrug-resistant
Kazuhiro Tateda1, Yoshikazu Ishii, Tetsuya Matsumoto
1Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Ohtaku, Tokyo, Japan. kazu@med.toho-u.ac.jp
Abstract:
Increase of multiple drug resistant Pseudomonas aeruginosa (MDRP) is becoming a serious problem in the clinical setting. Although the checkerboard method to determine FIC index and synergistic effects of antibiotic combinations is useful, it is not well adapted to a routine test, mainly because of its time-consuming and labor-intensive nature. Here we report 'Break-point Checkerboard Plate', in which breakpoint concentrations, such as 'S' (sensitive) and 'I' (intermediate), were combined in a microtiter plate with 8 antibiotics, including carbapenem, aminoglycoside and fluoroquinolone. The results obtained from 12 strains of MDRP demonstrated a strong synergistic effect of some antibiotic combinations at clinically relevant concentrations. Our data suggest a usefulness of 'Break-point Checkerboard Plate' to screen appropriate antibiotic combinations against drug resistant organisms, including MDRP.
Insights
A new
Area of Science:
- Clinical microbiology and infectious diseases.
- Antimicrobial resistance research.
- Pharmaceutical development.
Background:
- Rising prevalence of multidrug-resistant Pseudomonas aeruginosa (MDRP) poses a significant clinical challenge.
- Conventional checkerboard assays for antibiotic synergy are time-consuming and labor-intensive, hindering routine clinical application.
- Need for efficient methods to identify effective antibiotic combinations against resistant bacterial strains.
Purpose of the Study:
- To develop and evaluate a novel, rapid assay for screening antibiotic combinations against multidrug-resistant organisms.
- To assess the synergistic effects of antibiotic combinations at clinically relevant concentrations using the new assay.
- To determine the utility of the 'Break-point Checkerboard Plate' for routine testing against MDRP.
Main Methods:
- Development of the 'Break-point Checkerboard Plate' assay incorporating breakpoint concentrations (Susceptible 'S', Intermediate 'I') in a microtiter plate format.
- Testing of 8 different antibiotics, including carbapenem, aminoglycoside, and fluoroquinolone classes.
- Evaluation of the assay's performance using 12 clinical isolates of MDRP.
Main Results:
- The 'Break-point Checkerboard Plate' assay successfully identified synergistic effects for certain antibiotic combinations against MDRP strains.
- Observed synergistic effects were demonstrated at clinically relevant concentrations.
- The assay proved effective in screening antibiotic combinations for drug-resistant organisms.
Conclusions:
- The 'Break-point Checkerboard Plate' offers a more efficient alternative to traditional methods for assessing antibiotic synergy.
- This novel assay is valuable for screening effective antibiotic combinations against challenging multidrug-resistant pathogens like MDRP.
- The findings support the clinical utility of this assay in guiding antimicrobial therapy for resistant infections.
