Affordable automated phenotypic antibiotic susceptibility testing method based on a contactless conductometric sensor

Jinping Wang,Xuzhi Zhang,Keming Qu,Jun Zhao,Qianqian Yang,Xiaobo Sun,Yan Zhang,Xiaochun Wang,Guosi Xie,Yong Xu,Xiaoyu Jiang

doi:10.1038/s41598-020-77938-7

Abstract

User-friendly phenotypic antibiotic susceptibility testing (AST) methods are urgently needed in many fields including clinical medicine, epidemiological studies and drug research. Herein, we report a convenient and cost-effective phenotypic AST method based on online monitoring bacterial growth with a developed 8-channel contactless conductometric sensor (CCS). Using E. coli and V. parahaemolyticus as microorganism models, as well as enoxacin, florfenicol, ampicillin, kanamycin and sulfadiazine as antibiotic probes. The minimum inhibitory concentration (MIC) determination was validated in comparison with standard broth microdilution (BMD) assay. The total essential agreements between the CCS AST assays and the reference BMD AST assays are 68.8–92.3%. The CCS has an approximate price of $9,000 (USD). Requiring neither chemical nor biotic auxiliary materials for the assay makes the cost of each sample < $1. The MICs obtained with the automated CCS AST assays are more precise than those obtained with the manual BMD. Moreover, in 72 percent of the counterpart, the MICs obtained with the CCS AST assays are higher than that obtained with the BMD AST assays. The proposed CCS AST method has advantages in affordability, accuracy, sensitivity and user-friendliness.

Highlights

User-friendly phenotypic antibiotic susceptibility testing (AST) methods are urgently needed in many fields including clinical medicine, epidemiological studies and drug research
Reproducible and accurate measurements, automated AST methods have been developed in recent decades, and most available methods are divided into two categories based on mechanism: genotypic and phenotypic methods
The variation in apparent conductivity was very small (< 0.8%) over a period of 20 h in both cases. These results demonstrate the uniformity of temperature in the working chamber as well as robust and identical conductometric measurements

Summary

Introduction

User-friendly phenotypic antibiotic susceptibility testing (AST) methods are urgently needed in many fields including clinical medicine, epidemiological studies and drug research. The MICs obtained with the automated CCS AST assays are more precise than those obtained with the manual BMD. In 72 percent of the counterpart, the MICs obtained with the CCS AST assays are higher than that obtained with the BMD. Determining the susceptibility of microorganisms towards target agents (e.g., antibiotics and nanoparticles) is of great significance in many fields including medicine, epidemiology, drug research, environmental surveys and agriculture[1,2,3]. Antimicrobial susceptibility testing (AST) is the concentration of antimicrobial agents that is required to inhibit proliferation of target microorganisms in vitro and is the most valuable tool for. In most of these performances, the requirements of microbial growth are bypassed resulting in a fast response; the results can be obtained with high specificity and sensitivity within 2

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