Listeria monocytogenes isolated from a human case of invasive listeriosis survived more than 25 years in a blood culture bottle.

The aim of the present study was to determine whether L. monocytogenes bacteria from an invasive case of listeriosis cultured in a BacT/ALERT FA bottle in 1999 have survived, and if so, whether their pulsed-field gel electrophoresis (PFGE) profiles have changed. In 2024, after more than 25 years in a refrigerator, L. monocytogenes was isolated in pure culture from the BacT/ALERT FA bottle. All 100 selected isolates showed the same by PFGE profile with the restriction enzyme Asc I as the L. monocytogenes isolates did in 1999. L. monocytogenes can apparently survive for a long time in a nutrient-poor environment, and this must be taken into account by the food industry. Persistence in clinical samples has rarely been reported; however, several authors report persistence of L. monocytogenes in the food industry, with bacteria ending up in final products.