Infection source of a neonatal sepsis case caused by Listeria monocytogenes

Objective To understand the etiological and epidemiological characteristics of a neonatal sepsis case caused by Listeria monocytogenes in Zigong of Sichuan and provide reference for listeria disease prevention and control.

Methods The neonatal blood sample and maternal vaginal and vulva swabs were collected, and raw and ready-to eat food samples were collected from the open market near the home of the puerpera. Food samples in the refrigerator in home of the puerpera and environmental swabs of kitchen and bathroom were also collected. Meanwhile, self-designed questionnaire was used to conduct a face to face survey. L. monocytogenes strains isolated were used for serotyping. Multi locus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) were conducted to analyze the homology of strains.

Results Seven strains of L. monocytogenes strains were isolated from samples of the neonate and the puerpera, 1 strain was isolated from the food sample. All the 8 strains belonged to serotype 1/2b, the sequence type was ST87 and the similarity of PFGE type was 100%. The perinatal listeriosis was caused by vertical transmission, the strains isolated from the puerpera and ready-to-eat meat were from the same contamination source.

Conclusion Ready-to-eat meat products might be the important risk factor for the L. monocytogenes infection, it should be monitored in food safety risk surveillance project. The screening of L. monocytogenes should be an important part of antenatal examination.