The Research Of Piezoelectric Biosensor On Antimicrobial Susceptibility Testing

Antibiotics are one of the most frequently used drugs in clinical therapy. Inappropriate and overuse of antibiotics lead to not only the emergence of resistant bacteria but also economic loss and adverse reactions. So the rational use of antibiotic has aroused much attention in recent years. Antimicrobial susceptibility testing is an effective means of improving antibiotic use.Piezoelectric biosensor has been applied in many fields for its high sensitivity, broad sensing spectrum, simple operation and low cost. In this thesis, multi-channel series piezoelectric quartz crystal (MSPQC) was applied to do antimicrobial susceptibility testing, based on the response of SPQC to the change of electric parameters of medium, which related to some characteristics of the bacterial metabolism. The new methods broaden their application in clinical microbiology. The main content of this thesis is as follow:(1) A new antimicrobial susceptibility testing method by multi-channel series piezoelectric quartz crystal (MSPQC) was proposed. This method was used to test susceptibility of clinical Escherichia coli isolates against ampicillin, cefotaxime and gentamicin. Both the minimum inhibitory concentrations (MICs) and interpretive categorization of clinical E. coli isolates were determined by the proposed method. Comparing tests were run at the same time by the agar dilution method and the disk diffusion method. The experimental results showed that MSPQC method had a good agreement with the reference methods. Compared with those methods, the MSPQC method is simple, rapid, and convenient to perform. It can offer both a minimum inhibitory concentration (MIC) and an interpretive category result. It could be popularized in clinical microbiology laboratories.(2) A new sensor method based on multi-channel series piezoelectric quartz crystal (MSPQC) was proposed for studying the antibiotic dosing regimens. Cefotaxime and gentamicin were selected as time-dependence and concentration-dependence antibiotics individually. The influence of dosage, dosing time interval and dosing frequency on the growth of Escherichia coli ATCC 25922 were investigated in detail. The frequency shift curves under different regimens were obtained and compared with each other. Frequency detection time (FDT) was gained to assess the inhibitory effect. The optimal dosing regimens could be made according to the obtained information. (3) MSPQC method was proposed to assess the effect of gentamicin and cefotaxime combination against Escherichia coli ATCC 25922 in vitro. Synergism study was performed by the proposed method. Different combination regimens were also studied by MSPQC technique. Simultaneous/ nonsimultaneous administration, order and time interval of administration regimens were compared. The results of the present study can provide useful information to physicians in the selection of appropriate administration regimens.(4) MSPQC method was proposed to determine the antimicrobial adsorbent system. The effectiveness of three resins (XDA-16, CD-16 and H-103) and an anticoagulant SPS, to adsorb antibiotics (ampicillin, cefotaxime and gentamicin) were studied by the proposed method. Antibiotic removal was evaluated on frequency detection time (FDT). And the antimicrobial adsorbent system was determined based on the obtained results.