A new system for automated Raman pathogen susceptibility and rapid detection was developed

The automated CAST-R system serves clinical precision anti-infective therapy single cell center courtesy of the map

The spread of multidrug-resistant bacteria (MDR) and their drug resistance has become a global public health problem, and bloodstream infections caused by MDR are often more severe, and rapid completion of susceptibility testing and targeted treatment measures are essential to reduce mortality in patients. However, current pathogen susceptibility testing takes a long time, resulting in clinicians relying heavily on experience for treatment. Developing a simple, fast, accurate, and clinically broad-spectrum drug-susceptibility phenotypic test method has always been an urgent clinical task.

In view of this problem, the Single Cell Center of Qingdao Institute of Bioenergy and Bioprocess Research, Chinese Academy of Sciences, in cooperation with Peking Union Medical College Hospital, the Affiliated Hospital of Qingdao University and Qingdao Xingsai Biology, has established an automated version of the Raman Pathogen Susceptibility Rapid Detection System (CAST-R) using tegranine for the treatment of sepsis using tegranine as a model for the treatment of sepsis, using heavy water labeled single-cell Raman spectroscopy (D2O-SCRS), shortening the duration of drug susceptibility experiments (AST) for common pathogens (in positive culture flasks for blood infections) to 3 hours. Ten-fold acceleration is achieved, and susceptibility results can be obtained on the day the culture bottle is reported. The results of the study were recently published in the journal Microbiology. The work was co-chaired by Yang Qiwen, professor of the Department of Clinical Laboratory, Peking Union Medical College Hospital, and Xu Jian, a researcher at the Institute’s Single Cell Center.

Sepsis is an acute systemic infection caused by the invasion of pathogenic bacteria into the blood circulation. Among the pathogens that cause bloodstream infections, Acinetobacter baumannii is one of the most common pathogens. Currently, tigecycline is often the last line of defense for multi-drug-resistant or pan-resistant pathogen infections, such as bacterial infections such as Acinetobacter baumannii or carbalasene-resistant Enterobacterium.

However, clinical detection of the drug susceptibility of pathogens to tigecycline faces many difficulties. First of all, the physical and chemical properties of tigecycline are unstable, easy to oxidize and decompose, and the types of media, preparation time, detection methods, different strains and the choice of vertices have an impact on the in vitro susceptibility results of tigecycline. Secondly, the current drug susceptibility method has more difficulties and operational misunderstandings, and it is not easy to standardize.

At the Single Cell Center of the Qingdao Institute of Energy of the Chinese Academy of Sciences, the reporter saw that the “Xue Mingqiu Single Cell Drug Sensitive Rapid Detection Technology Assault Team” with young party members as the backbone overcame difficulties and launched several rounds of technical research. Led by Zhu Pengfei, Ren Lihui, Dai Jing of the Single Cell Center of the First Party Branch of Bioenergy, and Zhu Ying of Peking Union Medical College Hospital, together with researchers from Qingdao Xingsai Biological Company and the Affiliated Hospital of Qingdao University, starting from the samples in the positive blood culture flask, the sample was completed in one stop using the CAST-R Automated Liquid Processing Workstation (PLS) to complete the sample D2O incubation, automatic cleaning and chip positioning; The instrument’s built-in software (self-developed algorithm) is used to achieve accurate cell positioning and high-throughput Raman spectral acquisition; finally, combined with machine learning, the spectral acquisition process is automated and intelligent, as well as the quality control of the spectrum, and accurate drug susceptibility results are obtained. CAST-R can be directly automated susceptibility testing for pathogens in blood culture-positive culture flasks, increasing the speed by a factor of 10.

Previously, the research team of the Single Cell Center proposed the new concept of “minimum metabolic activity inhibition concentration (MIC-MA)”, which measures drug sensitivity, and on this basis, the new scientific research work introduced the concept of “eMIC-MA” to effectively exclude the influence of strain starting state and instrument changes on the detection results. The drug susceptibility of 100 acinetobacter Baumannii clinical isolates to tigecycline was tested by CAST-R, and the basic consistency rate and classification consistency rate compared with the clinical gold standard (trace broth dilution method; BMD) were 99% and 93%, respectively, thus verifying the accuracy and reliability of CAST-R.

In addition, for 26 patients with positive blood culture flasks, the drug sensitivity of common bloodstream infection bacteria to eight antibiotics, such as tigecycline, meropenem, ceftazidime and ampicillin/sulbactam, was measured, and the classification consistency rate reached 93% compared with the BMD results, which verified the broad-spectrum applicability of CAST-R in the use of bloodstream infections.

These results validate the speed, accuracy and reliability of the CAST-R automation system as well as its clinical applicability, accelerating its clinical application. In addition, using the Raman sorting and sequencing technology (RACS-Seq) technology (Xu, et al., Small, 2020) invented in the early stage of single-cell centers, CAST-R is expected to establish a link between drug resistance phenotype and genotype in single-cell precision, thereby tracking the emergence of superbugs and the spread of drug resistance.

The work was supported by Xu Yingchun, professor of the Department of Laboratory Medicine of Peking Union Medical College Hospital, Zhu Yuanqi, professor of the Department of Laboratory Medicine of the Affiliated Hospital of Qingdao University, and Ma Bo, a researcher at the Single Cell Center. It has won funding from the Pilot Project of the Chinese Academy of Sciences, the National Major Scientific Instrument Development Project of the Foundation Committee, the STS Regional Key Project of the Chinese Academy of Sciences, and the Guangzhou Biological Island Laboratory. (Source: China Science Daily, Liao Yang, Liu Jia, Liu Yang)

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