Aijin Chen,1 Xiang Chen,1 Zhou Zheng,2 Huaguo Wang,1 Mingpeng Hu1 

1Laboratory Department, Ruian Hospital of Traditional Chinese Medicine, Wenzhou, Zhejiang, People’s Republic of China; 2Laboratory Department, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, People’s Republic of China

Correspondence: Huaguo Wang, Ruian Hospital of Traditional Chinese Medicine, Wenzhou, People’s Republic of China, Email 6830543@qq.com Mingpeng Hu, Ruian Hospital of Traditional Chinese Medicine, Wenzhou, People’s Republic of China, Email 334707598@qq.com

Objective: To investigate the serotypes, virulence genes, and molecular typing characteristics of Listeria monocytogenes strains isolated from a hospital in Wenzhou City.
Methods: Polymerase chain reaction (PCR) was employed to detect the serotypes and virulence genes of Listeria monocytogenes, as well as to perform multilocus sequence typing (MLST). The broth microdilution method was utilized for susceptibility testing. Additionally, epidemiological survey data were integrated to explore the relationship between the absence of key virulence genes and the serotypes of Listeria monocytogenes.
Results: All strains exhibited sensitivity to penicillin, erythromycin, meropenem, and co-trimoxazole. The strains were primarily categorized into three serotypes: 1/2a, 1/2b, and 4b, with serotype 1/2b being the most prevalent, accounting for 70.59% of the isolates. MLST analysis identified nine sequence types (ST) and eight clonal complexes (CC), with ST87 (CC87) being the most common. Virulence gene analysis revealed that the carriage rates for inlA, inlC, plcB, prfA, mpl, iap, hly, inlB, plcA, and fbpA were 100%. In contrast, the carriage rates for actA, inlJ, and llsX were 70.59%, 47.06%, and 35.29%, respectively. The 1/2a serotype strain carried all virulence genes except for llsX, and no statistically significant differences were observed in the carriage rates of the 13 virulence genes among serotypes 1/2a, 1/2b, and 4b (P > 0.05).
Conclusion: The clinical isolates of Listeria monocytogenes in Wenzhou City exhibit polymorphism in MLST typing, predominantly ST87 (CC87) and serotype 1/2b. All strains harbored the major virulence genes, indicating their potential pathogenicity. This underscores the necessity for enhanced surveillance and preventive measures regarding the virulence genes of Listeria monocytogenes and antibiotic resistance.

Keywords: serotype diversity, antibiotic susceptibility, epidemiological surveillance, gene carriage rate, public health