A primer on use of inkjet printing and time-kill studies for combination antimicrobial susceptibility testing
Adopted by the CDC .in their Antimicrobial Resistance Laboratory Network based on our prior publications in Journal of Clinical Microbiology, Journal of Antimicrobial Chemotherapy, and Antimicrobial Agents and Chemotherapy for testing of aztreonam/ceftazidime-avibactam combination activity using inkjet printing. We provide a step by step video demonstration of assay setup in the Journal of Visualized Experimentation. Link to article landing page (PDF protocol access and video), "Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method" by Thea Brennan-Krohn and James E. Kirby.
JoVE manuscript accepted on use of Inkjet Printing to perform antimicrobial susceptibility testing for single and drug combinations and follow up time-kill study methodology
Postdoctoral fellow, Thea Brennan-Krohn, recently had a manuscript accepted in the Journal of Visualized Experimentation, aka JoVE. The title of the manuscript and link to the abstract are "Antimicrobial Synergy Testing by the Inkjet Printer-Assisted Automated Checkerboard Array and the Manual Time-Kill Method." We have been fielding a lot of questions over the past two years about implementation of inkjet printing antimicrobial susceptibility testing technology and thought it would be useful to share a video of the technique as well as classic time-kill analysis to analyze antimicrobial synergy. We are excited to learn that the CDC has decided to implement the technology in the near future in their Antimicrobial Resistance Laboratory Network (ARLN), initially to test, the combination of ceftazidime-avibactam and aztreonam for activity against multidrug-resistant Gram-negatives.
KP Smith Speaking tomorrow at Harvard Antimicrobial Resistance Laboratory Network as well as Broad Institute collaborator, Alejandro Pironti
"A Little Change Can Make a Lot of MIC Difference: the Inoculum Effect and Antibiotic Susceptibility Testing"
Thanks to American Society of Microbiology science writer, Julie Wolf, for highlighting our inoculum effect manuscript in the ASM mBiosphere Blog, "A Little Change Can Make a Lot of MIC Difference: the Inoculum Effect and Antibiotic Susceptibility Testing"
Synergistic Activity of Colistin-Containing Combinations against Colistin-Resistant Enterobacteriaceae.
Published online today in Antimicrobial Agents and Chemotherapy! Thea Brennan-Krohn, Alejandro Pironti, and James E. Kirby. Synergistic Activity of Colistin-Containing Combinations against Colistin-Resistant Enterobacteriaceae. Antimicrob. Agents Chemother. Accepted manuscript posted online 30 July 2018 , doi:10.1128/AAC.00873-18.
Now live on the Antimicrobial Agents and Chemotherapy Webpage: The Inoculum Effect in the Era of Multidrug Resistance: Minor Differences in Inoculum Have Dramatic Effect on MIC Determination.
Our inoculum effect manuscript in the journal Antimicrobial Agents and Chemotherapy highlighted in BIDMC news release.
"The Inoculum Effect in the Era of Multidrug Resistance: Minor Differences in Inoculum Have Dramatic Effect on Minimal Inhibitory Concentration Determination."
The manuscript describes use of D300-based inkjet printing technology to investigate the inoculum effect with a resolution not previously possible. The inoculum effect is the general observation that the minimal inhibitor concentration (in other words level of resistance) of an organism to an antibiotic increases when a higher density of organisms is tested. This is effect is especially prominent for beta-lactam antiibiotics. It is of potential clinical concern during some types of infections when the organism burden is high. Here we explored whether subtle differences in inoculum within the range allowed by current standards can effect the susceptibility testing results that clinical laboratories obtain and provide to clinicians. Our findings for organisms with certain types of multidrug-resistance and very important classes of antibiotics was that these small allowable differences in inoculum could change the MIC determinations and the determination of whether organisms were susceptible or resistant to the antibiotics tested.
KP Smith wins an "Outstanding Abstract Award" otherwise known as the OAA, for his experimental work on the inoculum effect.
The award description on the ASM Microbe 2018 awards website: "Sponsored by ASM and determined by the ASM Microbe Program Committee, these awards highlight outstanding abstracts presented by students, residents, or medical/clinical fellows. All abstracts submitted by the deadline will be considered for these awards. Awards will include a cash prize of $200."
Kirby Lab Blog