Category: Assay Development and Screening

1202-C - Rapid antimicrobial susceptibility testing based on analysis of single bacteria growth in microdroplets

Tuesday, February 6, 2018
2:00 PM - 3:00 PM

Recently, bacteria with antibiotic resistance and the related infections have widely affected and even threatened countless lives, and also caused an immense burden to the economies all over the world. Among the common infections, urinary tract infections (UTI) is one of the most frequently diagnosed infectious diseases and could cause severe complications, for instance, permanent kidney damage (chronic pyelonephritis) or even life-threatening bacterial sepsis etc. Since the current clinical settings lack quick and reliable approaches to determine the specific bacterial species/strains and to perform an in situ antimicrobial susceptibility testing (AST) for an effective treatment, most physicians have to continue applying broad-spectrum antibiotics. This would, in turn, worsen the bacterial antibiotic resistance and potentially place more danger in the future. Several widespread methods for AST include matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and nucleic acid amplification test (NAAT) such as polymerase chain reaction (PCR) etc. Though they could accurately detect the bacterial strains, these methods might suffer from prolonged measurement time (16−24 h) or are not able to disclose details about phenotype resistance, and the minimum inhibitory concentration (MIC) required in a treatment. To overcome these and to enable faster ASTs, microfluidics has thrived in recent decades, providing a series of promising solutions with advantages such as rapid analysis, possibilities for the study of bacterial phenotypes and growth kinetics, high throughput, and low-cost devices. In this work, we demonstrated a droplet microfluidic platform as an alternative for standard benchtop ASTs, which is capable of screening an array of thousands of picoliter microdroplets encapsulated with single bacteria − S.aureus 29213, E.faecalis 29212, E. coli ATCC 25922 and E. coli 6937, and antibiotics − oxacillin, ceftazidime and levofloxacin using time-lapse microscopy, which allows a thorough study of bacteria heterogeneity. We successfully determined the MIC for each strain within 1−4 h based on the bacterial proliferation outcome with the presence of different antibiotic concentrations, and validated the MIC with results from broth microdilution method in 96 well plates. This droplet microfluidic system could fulfill the urgent need of timely ASTs in clinical settings and avoid the excessive usages of antibiotics in large doses, and also facilitate the study of bacterial antibiotic resistance in the pharmaceutical industry.  

Wenjing Kang

Postdoctoral Research Associate
Northeastern University
Boston, MA

I have graduated as a Ph.D. in Electrical Engineering from Dr. Ian Papautsky’s lab, University of Cincinnati. My research primarily focused on the development and characterization of a series of microscale electrochemical sensors with thin film metal electrodes and the related portable systems for determination of hazardous trace metals in biological and environmental samples. I also have experience in the designing, manufacturing, and testing of microfluidic mixers. After graduation, I have been working as a volunteer research scientist on the development of bio-inspired polymers and nanoelectronics in Dr. Xiaocheng Jiang’s lab at the Department of Biomedical Engineering, Tufts University. Now I am working as a Postdoctoral Research Associate in Dr. Tania Konry's lab at the Department of Pharmaceutical Sciences, Northeastern University, mainly on droplet microfluidics for drug screening in antimicrobial susceptibility study and cancer immunology.