Presence of Listeria at primary production and processing of food of non-animal origin (FNAO) in Bavaria, Germany

Wartha, Simone; Huber, Stefanie; Kraemer, Iris; Alter, Thomas; Messelhäußer, Ute

doi:10.1016/j.jfp.2022.11.007

Cited by 7 publications

(8 citation statements)

References 21 publications

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“…The sampling scheme, number of samples, and Listeria spp. detection methods are already described by Wartha et al [ 23 ]. In addition to the 407 samples from 39 primary production and processing companies already described [ 23 ], 123 samples of fresh fruit and frozen berries from supermarkets were collected and analyzed.…”

Section: Methodsmentioning

confidence: 99%

“…detection methods are already described by Wartha et al [ 23 ]. In addition to the 407 samples from 39 primary production and processing companies already described [ 23 ], 123 samples of fresh fruit and frozen berries from supermarkets were collected and analyzed. The study of Wartha et al [ 23 ] was furthermore extended with WGS results of 64 detected Listeria spp.…”

Section: Methodsmentioning

confidence: 99%

“…In addition to the 407 samples from 39 primary production and processing companies already described [ 23 ], 123 samples of fresh fruit and frozen berries from supermarkets were collected and analyzed. The study of Wartha et al [ 23 ] was furthermore extended with WGS results of 64 detected Listeria spp. and L. monocytogenes isolates from FNAO products from supermarkets and FNAO-producing and -processing plants.…”

Section: Methodsmentioning

confidence: 99%

“…Thirty plants were categorized as primary production (i.e., farm and primary production level) and nine companies as processing companies (i.e., processing level). The 407 samples included 229 swab samples (food contact material and environment), 59 food samples (soft fruit, vegetables, RTE vegetables, and other food samples), and 119 irrigation and processing water samples [ 23 ]. For the detection of Listeria spp.…”

Section: Methodsmentioning

confidence: 99%

“…For the detection of Listeria spp. and L. monocytogenes , ISO 11290–1:2017 [ 24 ] was used as described [ 23 ].…”

Section: Methodsmentioning

confidence: 99%

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Genetic Characterization of Listeria from Food of Non-Animal Origin Products and from Producing and Processing Companies in Bavaria, Germany

Wartha¹,

Bretschneider²,

Dangel³

et al. 2023

Foods

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Reported cases of listeriosis from food of non-animal origin (FNAO) are increasing. In order to assess the risk of exposure to Listeria monocytogenes from FNAO, the genetic characterization of the pathogen in FNAO products and in primary production and processing plants needs to be investigated. For this, 123 samples of fresh and frozen soft fruit and 407 samples of 39 plants in Bavaria, Germany that produce and process FNAO were investigated for Listeria contamination. As a result, 64 Listeria spp. isolates were detected using ISO 11290-1:2017. Environmental swabs and water and food samples were investigated. L. seeligeri (36/64, 56.25%) was the most frequently identified species, followed by L. monocytogenes (8/64, 12.50%), L. innocua (8/64, 12.50%), L. ivanovii (6/64, 9.38%), L. newyorkensis (5/64, 7.81%), and L. grayi (1/64, 1.56%). Those isolates were subsequently sequenced by whole-genome sequencing and subjected to pangenome analysis to retrieve data on the genotype, serotype, antimicrobial resistance (AMR), and virulence markers. Eight out of sixty-four Listeria spp. isolates were identified as L. monocytogenes. The serogroup analysis detected that 62.5% of the L. monocytogenes isolates belonged to serogroup IIa (1/2a and 3a) and 37.5% to serogroup IVb (4b, 4d, and 4e). Furthermore, the MLST (multilocus sequence typing) analysis of the eight detected L. monocytogenes isolates identified seven different sequence types (STs) and clonal complexes (CCs), i.e., ST1/CC1, ST2/CC2, ST6/CC6, ST7/CC7, ST21/CC21, ST504/CC475, and ST1413/CC739. The core genome MLST analysis also showed high allelic differences and suggests plant-specific isolates. Regarding the AMR, we detected phenotypic resistance against benzylpenicillin, fosfomycin, and moxifloxacin in all eight L. monocytogenes isolates. Moreover, virulence factors, such as prfA, hly, plcA, plcB, hpt, actA, inlA, inlB, and mpl, were identified in pathogenic and nonpathogenic Listeria species. The significance of L. monocytogenes in FNAO is growing and should receive increasing levels of attention.

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Section: Methodsmentioning

confidence: 99%