Molecular subtyping of Listeria monocytogenes isolated from patients in Xicheng district, Beijing, 2015–2019

  Objective  To study the serotype and molecular characteristics of Listeria monocytogenes isolated from patients in Xicheng district of Beijing from 2015 to 2019.

  Methods  A total of 40 L. monocytogenes strains isolated from the patients from 2015 to 2019 were characterized by serotyping with multiplex PCR, pulsed field gel electrophoresis (PFGE) and multilocus sequence tying (MLST) analysis.

  Results  In the 40 L. monocytogenes infection cases in this study, 14 were pregnancy related infection cases. 7 were neonatal infection cases, all were cured. In non-pregnancy related infection cases, 3 were fetal. In the 40 L. monocytogenes isolates, 3 serogroups were detected, in which 1/2a, 3a was predominant. The 40 strains were divided into 26 different PFGE types, GX6A16.BJ0003 was predominant (9 strains, 22.5%), and GX6A16.BJ0003 was detected in each year from 2015 to 2019, causing 2 deaths. The 2 cases associated with GX6A16.BJ0014 were all pregnancy related infections. The 40 strains were divided into 13 ST types based on MLST typing, the most common ST was ST8, ST87 and ST5.

  Construction  The predominant serogroup of L. monocytogenes isolated from patients in Xicheng district was 1/2a, 3a from 2015 to 2019. GX6A16.BJ0003 and ST8 were the predominant PFGE type and sequence type, respectively. There was persistence of spread of L. monocytogenes of same clone in Xicheng district. It is necessary to pay close attention the surveillance for high-risk pulse types.