Blood Culture Detection Method Based On Tunable Diode Laser Absorption Spectroscopy

Recently, medical technology is improving constantly with the rapid development of science and technology. A variety of diagnostic treatment methods such as organ transplantation, anticancer drugs and many ways of interventional examination and treatment, are growing, which is greatly improving the diagnosis and treatment level. At the same time, because of these methods, bacterial infections in the blood is following because of these methods. For example, the infection rate of Sepsis and bacteremia to increase year by year. Due to the high mortality rate of infection of these diseases, and rapid diagnosis of infection in blood is very important. Blood cultures report is an important basis for the diagnosis of these diseases, its accuracy is crucial for patients. In our country, the accuracy rate of blood cultures detection is generally low. By improving the positive rate of blood culture, objectively reflecting the actual situation of the patient’s blood infection sepsis pathogens, we need to improve the accuracy of detection.Blood culture can be detected indirectly by the presence of byproducts given off by the microorganism during its growth. The main indirectly approach for blood cultures detection is chemical sensing technology and fluorescence detection technology at present. The former mechanism is based on the change of carbon dioxide sensor which is imbedded at the bottom of the blood culture bottle, where the PH value of the sensor changes with the concentration T of CO2. The latter mechanism is the change of fluorescence intensity while the Carbon dioxide grows up in the metabolism or break down sugar of bacteria. Two kinds of detection methods are implementation by implanting carbon dioxide sensors or filling fluorescence photographic materials in the culture bottle respectively. CO2interacts with the material on the sensors. Because the concentration of CO2is detected secondhand, the two kind of detection methods have many shortcomings such as low sensitivity which causes the long examined period, more materials need be involved which causes more pollution and resource waste. In order to solve the existing problems, a detection method based on tunable diode laser absorption spectroscopy technique is given in this paper.As is a highly sensitive, highly selective, noninvasive and real-time trace gas detection technique, the Tunable Diode Laser Absorption Spectroscopy (TDLAS) has been widely used in atmospheric monitoring and industrial control which has promising application in the field of blood culture. The new method combined with the matured technique could be more reliable in the process of examines because of its non-invasive, and is more rapid and more accurate because of technique’s feature of TDLAS.In this study, we use the TDLAS technology to realize the detection of bacteria, which based on the amounts of carbon dioxide are produced in the process of metabolism by bacteria. Firstly, through the theoretical analysis and numerical simulation, we choose a CO2absorption lines "R16" which locate at2004nm wavelength belonging to "20012-00001" vibration band as the measurement goal. Then we conducted a series of experimental tests for some pathogenic bacteria which are common in clinical. Such experimental results attested that TDLAS technology can be used to investigate blood culture’s process, and get a concentration change curve of CO2in the process of bacterial growth. CO2concentration are all consistent with the laws of bacterial growth, it can provide the basis for future research in this field. And the result have a high detection sensitivity, because of CO2which is released by bacteria of100cfu can be measured accurately in6hours, which will meet the requirements of clinical test. Finally, we fitting the curves of bacterial growth time and the concentration of CO2according to the experimental data, and giving the fitting equation. These research results provide some references for using TDLAS technology to detect microbes. In last, we summarize the full text, and put forward the prospect of future work.