Detection of Microbial Growth Based on Conductance Method

• Main Authors: Tai-Yuan Zeng, 曾泰源
• Other Authors: Hsien-Chang Chang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/29016952514134810739

碩士 === 國立成功大學 === 醫學工程研究所 === 88 === The development of sensors that enabled a faster and reliable detection of pathogenic microorganisms has evolved towards biosensing technologies recently. Although conventional methods can provide accurate results, the process is relatively time-consuming. The detection normally takes 1 to 2 days. Thus, the methods are not sufficient for the detection of some acute diseases associated with bacteria infections such as bacteriuria and bacteremia. Therefore, additional to rapid and accurate detection, a sensitive and real-time measurement is important in preventive and clinical diagnosis. In this study, two microbial detection systems based on conductance method had been developed. The microorganisms could be quantified using this method. Microorganisms were detected through the blocking of electric pathways with carbon dioxide (CO2) bubbles produced during the metabolisms of the microorganisms. The detection of facultative anaerobic bacteria was through a capillary system. Bacteria were cultured in a sealed capillary tube filled with culture medium. Carbon dioxide bubbles formed would reduce the pH value in the medium and also generate a blockage in the capillary. Thus, stopping the conductivity signal. This system was applied for the susceptibility testing of bacteria. A total of four samples including two strains of E. coli, one strain of pneumonia and one strain of E. cloacae were tested. Each of them was tested three times against four antibiotics (Ampicillin, Cephalothin, Amikacin and Gentamicin). The reproducibility for all agents was 100% in the 1log2-dilution range. And the concentration highly corresponded to the minimum inhibitory concentration (MIC) (in the range of 1log2) obtained from the conventional macrodilution method. On the other hand, the detection of yeast was by filter membrane system. Yeasts were concentrated on the filter membrane in a narrow tube by self-settling or filtering. The gaseous metabolisms were collected and used as a blockage to the electric pathway. As a result producing a strong signal response of conductivity. The detection time (DT) for C. albicans CCRC 20512 was 65 to 1100 minutes with the cell number in the range of 103 to 107 cfu/ml. The resulting detection time showed high concordance to the detection time of the conventional methods. The correlation coefficient, R-squared, (R2) was 0.9733 for 26 yeast samples. In conclusion, the microbial detection systems based on conductivity are new methods to quantify and to test the susceptibility of microorganisms. In addition, providing a rapid and reliable detection of microorganisms. Together with multi-channel automatic detection system, these methods can avoid both human and analysis errors, in return improving in early detection and effective clinical diagnosis.