Homology Analysis Of Bacteria In Nosocomial Infection By MALDI-TOF MS

Objective: To investigate the application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry( MALDI-TOF MS) on the homology analysis of bacteria and its clinical value.Methods: Klebsiella pneumoniae strains ATCC700603 as quality control were used to determine the optimal culture conditions for the identification of Klebsiella pneumonia by MALDI-TOF MS. 20 strains of Klebsiella pneumoniae collected from Feb to Apr in 2013[A] were analyzed with pulsed-field gel electrophoresis(PFGE), multilocus sequence typing(MLST) and MALDI- TOF MS for the homology analysis, in which the homology analysis ability of MALDI-TOF MS was evaluated with MALDI-Biotyper software. MALDI- TOF MS was also used for the homology analysis of 15 strains of Corynebacterium striatum collected from Nov in 2015 to Feb in 2016[B] and 9 strains of Klebsiella pneumoniae from Feb to Mar in 2016[C].Results: The optimal culture medium and incubation time of Klebsiella pneumonia was Columbia blood tablet and 24 h by MALDI- TOF MS. Almost the same result was obtained by the homology analysis of three above methods. A was identified by MALDI-TOF MS successfully and divided into cluster I(7 strains from ICU) and cluster II(13 strains from other departments) during homology analysis, and the protein spectrum of 7 strains from ICU were essentially the same which also reflect the close homology relationship. In the homology analysis of B and C, the isolated strains were divided into cluster I from ICU and cluster â…¡ from other departments by MALDI-TOF MS. The protein spectrum of 3 strains Klebsiella pneumonia from ICU were essentially the same and the results of antibiotic susceptibility testing were the same which were resistant to carbapenem antibiotics.Conclusion: MALDI-TOF MS as a convinent and rapid techenique can be used to identify Klebsiella pneumoniae accurately and analyze its homology in hospital. As there are nosocomial infection outbreak of Corynebacterium striatum and Klebsiella pneumonia in ICU, the disinfection and isolation are essential and the improvement of responsibility and protective consciousness of the medical staff is also important.