Warning Letter Indicates Facility has Same Listeria Strains in Plant for Years

In an FDA Warning Letter recently issued to Resers Fine Foods in relation to investigation conducted around Listeria issues in 2013 and 2016, FDA indicated that they found the same strain in the facility.  This shows the difficulty in getting rid of Listeria in the environment, and the need to continuously control that environment, especially once LM is found.

From that Warning Letter:

"Furthermore, this was not the first time FDA investigators collected environmental samples from your facility that were found to be positive for L. monocytogenes. Environmental samples (FDA 821317 and FDA 821318) collected during our 2013 inspection revealed L. monocytogenes in six (6) environmental subsample swabs in various locations within your facility, including in floor gaps, wheels of forklift and carts that are moved throughout the facility, and floor drains. Additionally, an environmental sample (FDA 862365) collected during our 2014 inspection revealed L. monocytogenes in two (2) environmental subsample swabs in locations within your facility, including on the wheel of a fork lift and v-mag number.

Whole Genome Sequencing (WGS) analysis was conducted on six (6) L. monocytogenes isolates obtained from the FDA environmental samples collected in November 2015, two (2) L. monocytogenes isolates obtained from the FDA environmental samples collected in August 2014, and six (6) L. monocytogenes isolates obtained from the FDA environmental samples collected in November 2013. WGS analysis of bacterial human pathogens provides high-resolution data, enabling direct links to be established between clinical isolates and food or environmental sources of bacterial contamination and illness. WGS data can also be used to infer the evolutionary relationships (or phylogeny) within a given set of isolates as it measures each DNA position in a bacterial genome. The WGS phylogenetic analysis found that there are at least three (3) different strains of L. monocytogenes present in the facility. The WGS results show that one (1) of these strains includes isolates that have been found over a period of time. Specifically, four (4) of the environmental isolates collected in November 2015, one (1) of the environmental isolates collected in August 2014, and four (4) of the environmental isolates collected in November 2013, were identical by WGS analysis.

The evidence demonstrates that L. monocytogenes has maintained its presence within your production facility since November 2013. The reoccurring presence of identical strains of L. monocytogenes in your environment indicates a resident strain or niche harborage site present in the facility. These findings also demonstrate that your sanitation procedures have historically been inadequate to control, reduce, or eliminate this pathogenic organism from your facility. It is essential to identify the areas of the food processing plant where this organism is able to grow and survive and to take such corrective actions as necessary to eradicate the organism by rendering these areas unable to support the growth and survival of the organism.

Furthermore, L. monocytogenes found in the environment of your facility increases the risk of your finished product becoming contaminated. Once established in a production area, humans or machinery can facilitate the pathogen’s movement and contamination of food-contact surfaces and finished product. FDA acknowledges that one of the environmental swabs from the November 2015 inspection that tested positive for L. monocytogenes was taken from a food contact surface used to carry potato salad. As a result of this finding, your firm conducted a voluntary recall on December 1, 2015 of a single lot of potato salad product."