ABSTRACT
Objective@#To establish the domestic matrix assisted laser desorption/ionisation time of flight mass spectrometry database for identification of clinical mycobacteria and evaluate its accuracy with foreign counterpart. @*Methods@#The establishment of "Chinese Pathogenic Mycobacteria Mass Spectrometry Database" : nineteen American type culture collection strains from 19 species and 183 "standardized" isolates from 42 species were selected and extracted by modified ultrasonic extraction method for spectral acquisition and database establishment based on microTyper MS. Each extract was dropped onto 12 spots and tested twice to generate 24 spectrum, then at least 20 qualified spectrum according to the standard were selected. Subsequently they were composed into one main spectra (MSP) by setting peak number maximum, peak frequency minimum and mass tolerance. Verification of database: Totally 305 mycobacteria from different regions were used for comparison of accuracy and spectral features between microTyper MS based on domestic database and imported MALDI TOF MS base on Mycobacteria Library 3.0 database. @*Results@#The database composed of 202 stains from 42 species was constructed, with an average of 4.8 in each species. The top ten were M. Kansasii(16), M. intracellulare(16), M. gordonae(16), M. fortuitum(16), M. avium(16), M. abscessus(16), M. tuberculosis(15), M. marseillense(11), M. arupense(10), M. yongongens(8). A total of 305 isolates were confirmed belonging to 22 species by sequencing. The accuracy based on this database was 99.67% (304/305), which was better than the Mycobacteria Library 3.0 database (χ2=4.06, P<0.05). @*Conclusion@#The construction of the "Chinese Pathogenic Mycobacteria Mass Spectrometry Database" meets the requirement of routine clinical application and was more accurate than its counterpart in terms of domestic comment strains.(Chin J Lab Med, 2018, 41: 519-526)
ABSTRACT
Objective To investigate the epidemic tendency and drug resistance of common pathogenic bacteria in the patients with infectious diarrhea,and then provide scientific evidence for the treatment of bacterial diarrhea.Methods The feces specimens were collected from 12 156 patients with infectious diarrhea in our hospital during April 1,2012 and October 31,2017.Then,they were cultured,and the obtained bacteria were isolated and identified by the Vitek 2 Compact system and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS).The serotype and drug resistance of the obtained bacteria were analyzed by the agglutination test and K-B disk diffnsion method,respectively.Results A total of 1 218 strains (10.02％,1 218/12 156) of pathogenic bacteria were isolated from 12 156 feces specimens,including 926 (7.62％,926/12 156) strains of Vibrio,96 (0.79％,96/12 156) strains of Aeromonas,178 (1.46％,178/12 156) strains of Salmonella and 18 (0.15％,18/12 156) strains of Shigella.The detection rates of pathogenic bacteria per year were 9.2％,11.9％,13.4％,7.0％,11.3％ and 7.2％,respectively,from 2012 to 2017.The detection rate of Shigella was low,but it had a high resistance to ampicillin and compound sulfamethoxazole (SMZ-TMP).Other pathogenic bacteria were more sensitive to SMZ-TMP,ceftriaxone,aztreonam,gentamycin and quinolones except ampicillin.Conclusion The main pathogenic bacterium in the patients with infectious diarrhea is Vibrio,and Shigella has the highest resistance to most drugs.The overall infection tendency is sporadic.It is necessary to strengthen the monitoring of pathogenic bacteria and their drug resistance in the patients with infectious diarrhea.
ABSTRACT
The matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is one of the first choice techniques for clinical microbiological identification owing to its fast,accuracy,low cost and easy to be operated.The accuracy of identification of MALDI-TOF MS relies on good instrument status,appropriate pre-trement,standardized operation and the rules of interpretation.Any errors in this process will directly influence the accuracy of identification.Therefore,strict internal quality control for the microbiological identification by MALDI-TOF MS is very important.Based on six years of research and clinical application experience,our laboratory establishes a relatively complete internal quality control system for the microbiological identification by MALDI-TOF MS,including all aspects of hardware,software and manual operation,the parameter settings,maintenance and calibration of the instrument,the preparation of strains and reagents,spectra acquisition and the interpretation and analysis of results,Which can make abnormal results be quickly traced and timely handled.
ABSTRACT
Accurate diagnosis and treatment of infectious diseases are vital, in which rapid, efficient,precise and comprehensive laboratorial detection plays a crucial role.The emergence of mass spectrometry technique revolutionized the test for biomacromolecule in clinical laboratory.The contribution of matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI -TOF MS)for laboratory diagnosis of infectious diseases was particularly significant.With the knowledge about the principles of MALDI-TOF MS and microbiology,it is not only able to allow you to have an insight into the details,but also help you to further develop and expand the application.Holographic mass spectrometry consists of, liquid chromatography -mass spectrometry(LC -MS)and gas chromatography -mass spectrometer(GC -MS)becomes a pipe dream.The combination of the three mass spectrometer technologies complement each others advantages,so that the application can be extended.They can not only accurately confirm the pathogens, but also detect the immune response products, metabolite and molecular markers of infectious diseases in order to obtain more comprehensive information of both pathogens and hosts, so that the laboratorial diagnosis can be more comprehensive, precise and individual.The application of holographic mass spectrometry breaks through the classic method and nucleic acid detection technology.It can not only embody speediness and accuracy, but also reflect the promotion of science level and research capability.