Persistence of <i>Listeria monocytogenes</i> strains in a frozen vegetables processing plant determined by serotyping and REP‐PCR

Ballesteros, Lorena; Moreno, Yolanda; Cuesta, G.; Rodrigo, Alejandro; Tomás, David; Hernandez, M.; Ferrús, María Antonia; Henández, Jorge García

doi:10.1111/j.1365-2621.2011.02595.x

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…The serotypes 1/2a, 1/2b and 4b are responsible for over 95% of the cases of listeriosis in humans, of which 1/2a and 1/2b have been mostly isolated from food and 4b from clinical cases [ 39 , 40 ]. In agreement with our results, the serotypes 1/2a, followed by 1/2b and 4b, have been isolated from frozen vegetables in different countries such as Spain, Switzerland and Chile [ 41 , 42 , 43 ]. In contrast, Braga et al [ 14 ] published that serotypes 1/2b and 4b were the most frequently detected in frozen foods, though frozen vegetables were not included in that study.…”

Section: Discussionsupporting

confidence: 91%

Frozen Vegetable Processing Plants Can Harbour Diverse Listeria monocytogenes Populations: Identification of Critical Operations by WGS

Truchado

Gil

Querido-Ferreira

et al. 2022

Foods

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Frozen vegetables have emerged as a concern due to their association with foodborne outbreaks such as the multi-country outbreak of Listeria monocytogenes serogroup IVb linked to frozen corn. The capacity of L. monocytogenes to colonize food-processing environments is well-known, making the bacteria a real problem for consumers. However, the significance of the processing environment in the contamination of frozen foods is not well established. This study aimed to identify potential contamination niches of L. monocytogenes in a frozen processing plant and characterize the recovered isolates. A frozen vegetable processing plant was monitored before cleaning activities. A total of 78 points were sampled, including frozen vegetables. Environmental samples belonged to food-contact surfaces (FCS); and non-food-contact surfaces (n-FCS). Positive L. monocytogenes samples were found in FCS (n = 4), n-FCS (n = 9), and the final product (n = 1). A whole-genome sequencing (WGS) analysis revealed two clusters belonging to serotypes 1/2a-3a and 1/2b-3b). The genetic characterization revealed the presence of four different sequence types previously detected in the food industry. The isolate obtained from the final product was the same as one isolate found in n-FCS. A multi-virulence-locus sequence typing (MVLST) analysis showed four different virulence types (VT). The results obtained highlight the relevant role that n-FCS such as floors and drains can play in spreading L. monocytogenes contamination to the final product.

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Section: Discussionsupporting

confidence: 91%

Frozen Vegetable Processing Plants Can Harbour Diverse Listeria monocytogenes Populations: Identification of Critical Operations by WGS

Truchado

Gil

Querido-Ferreira

et al. 2022

Foods

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“…It can adhere to many surfaces and form biofilms, and has the ability to survive and grow at low temperatures, a wide range of pH, high salt concentrations and low water activity ( Duffy and Sheridan, 1997 ; Miettinen et al, 1999a , b ; Freitag et al, 2009 ). L. monocytogenes has been isolated from various food products, including raw and cooked meats, milk products, seafood and vegetables ( Ballesteros et al, 2011 ; Jami et al, 2014 ; Moosavy et al, 2014 ; Brown et al, 2016 ; Luo et al, 2017 ). High levels of L. monocytogenes contamination in raw pork in China have been reported ( Zhang et al, 2007 , 2013 ; Yang et al, 2008 ; Huo et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Risk Factors and Level of Listeria monocytogenes Contamination of Raw Pork in Retail Markets in China

Wang

Lan

et al. 2018

Front. Microbiol.

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Listeria monocytogenes can contaminate various foods via food processing environments and contamination of raw materials. There is a limited understanding of L. monocytogenes transmission in retail market and the role of insects in L. monocytogenes transmission in the retail environments. To better understand the risk factors of raw pork contamination, the prevalence of L. monocytogenes was examined in raw pork, retail environments and insects in a retail market over a 6-month period from March to August in 2016 in Beijing, China. A total of 2,789 samples were collected, including 356 raw pork samples, 1,392 meat contact surface swabs (MCS), 712 non-meat contact surface swabs (NMCS) and 329 insect samples. Overall, 424 (15.20%) of the samples were found to be contaminated by L. monocytogenes. Analyzed by serotyping, multilocus sequence typing and pulsed-field gel electrophoresis, the 424 L. monocytogenes isolates were divided into three serotypes (1/2c, 1/2a and 3a), 15 pulsotypes (PTs) and nine sequence types (STs), 1/2c/PT4/ST9 (244/424, 58%) was the most prevalent type of L. monocytogenes strains. The raw pork, MCS of the environments and insects were contaminated with higher levels of L. monocytogenes than NMCS of the environments, which suggested that cross contamination of L. monocytogenes between raw pork and the environment existed in the retail market, and long-term contaminated surfaces and vector insects would act as high risk factors to transmit L. monocytogenes to raw pork. Thus more effective strategies are needed to reduce the risk of retail pork meat contamination by L. monocytogenes and prevent foodborne human listeriosis.

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“…Only few studies have focused on fresh FVH processing plants and further research is needed to address the prevalence and persistence of specific L. monocytogenes subtypes within the environments of fresh FVH farms and freezing plants. In general, the majority of strains isolated from frozen vegetables (final product) at the processing plant level seem to belong mainly to serotypes 1/2a followed by 1/2b, 1/2c and 4b (Ballesteros et al, 2011). In one of the two studies, serotypes 1/2b showed a significant adherence capacity when compared to serotypes 4b (Sant'Ana et al, 2012).…”

Section: Biofilms and Persistent Cellsmentioning

confidence: 98%

Urgent scientific and technical assistance to provide recommendations for sampling and testing in the processing plants of frozen vegetables aiming at detecting Listeria monocytogenes

Allende¹,

Barre²,

Jacxsens³

et al. 2018

EFSA Supporting Publications

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EFSA JournalAbstract EFSA was requested to provide recommendations to the European Commission on the sampling strategies and established microbiological methods most appropriate for maximising the sensitivity of detection of L. monocytogenes in processing water and the environment of premises producing frozen fruits, vegetables or herbs (FVH) as well as on the final food produced; and on the identification of critical sampling sites (CSSs) for environmental monitoring of L. monocytogenes. Seven steps are defined for a fit-for-purpose sampling strategy which is expected to support competent authorities and food business operators in foodborne outbreak investigations where frozen FVH are implicated. The relevant CSSs can be defined based upon critical inspection inside a freezing plant and the background information described in this report. Typical non-food contact surfaces where L. monocytogenes can harbour in a freezing plant include: floors, especially cracks and crevices, walls, drains, ceilings, overhead structures, catwalks, wash areas, condensate and standing water, wet insulation in walls and around pipes and cooling units, rubber seals around doors, especially in coolers, metal joints, specially welds and bolts and contents of vacuum cleaners. L. monocytogenes is also commonly found on equipment used for food processing, preparation, storage, and transportation such as freezing tunnels, castings bowls, blade spinner, slicers, knives, cutting boards, conveyor belts, gloves joints, gaskets and dead ends. A concerted effort should be made to plan the sampling around production batches and environmental CSSs. Sampling procedures should be performed as exhaustively as possible covering the largest number of CSSs and samples per CSS to gain insight into the potential variability of the contamination sources. EN ISO standard method 11290-1 is recommended for L. monocytogenes detection. Characterization of L. monocytogenes isolates using well established molecular techniques is needed to identify strains from positive samples and establish links between isolates from humans and from implicated FVH.

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Persistence of Listeria monocytogenes strains in a frozen vegetables processing plant determined by serotyping and REP‐PCR

Cited by 12 publications

References 15 publications

Frozen Vegetable Processing Plants Can Harbour Diverse Listeria monocytogenes Populations: Identification of Critical Operations by WGS

Frozen Vegetable Processing Plants Can Harbour Diverse Listeria monocytogenes Populations: Identification of Critical Operations by WGS

Risk Factors and Level of Listeria monocytogenes Contamination of Raw Pork in Retail Markets in China

Urgent scientific and technical assistance to provide recommendations for sampling and testing in the processing plants of frozen vegetables aiming at detecting Listeria monocytogenes

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