Application and evaluation of VITEK-2 Compact and VITEK MS in identification of Morganella morganii

  Objective  To analyze the application of VITEK-2 Compact and VITEK MS in the identification of Morganella morganii, evaluate the accuracy of the identification results and provides evidence for clinical precision treatment.

  Methods  We collected 50 strains of M. morganii isolated from different types of samples in our hospital from January 2017 to May 2020. The bacterial strains were cultured by conventional methods. Then, VITEK-2 Compact, manual biochemical supplementary test and VITEK MS were used to identify the strains. The strains with different identification results were verified by 16S rDNA sequencing.

  Results  The 50 strains of M. morganii were composed of 5 strains of beta-hemolytic phenotype and 45 strains of non-beta-hemolytic phenotype. VITEK-2 Compact had consistent identification results for non-beta-hemolytic M. morganii, but not for beta-hemolytic M. morganii, which were all identified as Proteus mirabilis, the identification consistent rate was 90%, and manual biochemical supplementary test had same results. The identification results of VITEK MS for non-beta-hemolytic and beta-hemolytic M. morganii were consistent, and the identification consistent rates were 100%. 16S rDNA sequencing verified the five beta-hemolytic strains of M. morganii, which had non-consistent identification results in previous identifications.

  Conclusion  VITEK-2 Compact was accurate and reliable for the identification of non-beta hemolytic M. morganii, but its identifications of beta-hemolytic M. morganii were inaccurate, and the probability of false identification as Proteus mirabilis was very high. The identification result of VITEK MS for M. morganii was accurate and it was not affected by the beta-hemolytic phenotype.