Tracing the source of the first listeriosis case in a pregnant woman caused by Chinese cold dishes in Jiangxi Province

Abstract

ObjectiveThis study aimed to trace the source of a listeriosis case in a pregnant woman linked to the consumption of Chinese cold dishes in Jiangxi Province.MethodsA descriptive epidemiological investigation was conducted to gather patient information. Listeria monocytogenes strains from both food and blood samples were isolated using the national standard GB 4789.30—2016 methods and clinical test methods. The isolated strains were identified using biochemical and mass spectrometry methods. Subtyping and source tracing of the strains were performed using pulsed field gel electrophoresis and whole genome sequencing.ResultsThe patient exhibited fever as the primary symptom of L. monocytogenes infection， while the fetus was not affected. The patient reported a weekly habit of consuming Chinese cold dishes. Blood culture from the patient yielded a strain of L. monocytogenes， whereas no L. monocytogenes strains were found in field samples collected from the patient’s home. However， the bacteria were detected and isolated from two Chinese cold dishes purchased from restaurants frequented by the patient. Pulsed-field gel electrophoresis typing confirmed complete consistency between the patient-isolated strains and those isolated from the food. Whole genome sequencing revealed that the strains belonged to the ST1 type.ConclusionThe risk of listeriosis in pregnant women associated with Chinese cold dishes persists. Enhanced monitoring measures are warranted， and relevant authorities should intensify their supervision of associated restaurants.

Keywords

• listeria monocytogenes
• food source
• chinese cold dishes
• listeriosis