Publication Database

Listeria monocytogenes in food of non-animal origin (2023)

Art

Hochschulschrift

Autor

Wartha, Simone Erika (WE 8)

Quelle

Berlin: Mensch und Buch Verlag, 2023 — X, 145 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/41900

Kontakt

Institut für Lebensmittelsicherheit und -hygiene

Königsweg 69
14163 Berlin
+49 30 838 62551 / 52790
lebensmittelhygiene@vetmed.fu-berlin.de / fleischhygiene@vetmed.fu-berlin.de

Abstract / Zusammenfassung

L. monocytogenes is a Gram-positive pathogenic bacterium causing the foodborne disease listeriosis, esp. in vulnerable population groups called YOPIs. Compared to other foodborne pathogenic microorganisms, the fatality rate of 20–30% of severe listeriosis is a serious concern. Listeriosis cases associated with FNAO have been increasing in recent years. In particular, RTE FNAO without any further processing steps like heating is of great concern in this context. This study investigated 39 FNAO primary producers and processing companies that produce and process FNAO products in Bavaria, Germany from July 2020 until June 2021 (Chapter 3). The categories were “producers of soft fruit”, “producers of vegetables” and “producers of RTE raw fruits and vegetables/fresh cut”. The aim of this study was to detect the prevalence of Listeria spp. and L. monocytogenes in FNAO producing and processing plants. In general, 407 samples from the processing environment (229 samples), the food (59 samples) and irrigation and processing water (119 samples) were taken and investigated using ISO 11290 - 1:2017. Overall, in 12.53% of the samples Listeria spp. and L. monocytogenes were detected. L. monocytogenes isolates were identified in the FNAO surrounding, especially drains, and in a sample of processing water. Whereas no food was contaminated with the pathogenic L. monocytogenes. Irrigation and processing water are probable contamination sources of FNAO. Unhygienic circumstances of water pipelines pose a risk of cross-contamination. Furthermore, the detected Listeria spp. and L. monocytogenes isolates were sequenced with WGS (Chapter 4). It poses the question about genetic relationship within and between companies. Due to low genetic relationship of Listeria spp. and L. monocytogenes within and between companies, external introduction and plant-specific Listeria in FNAO facilities were suggested. In particular, incoming raw material is discussed but irrigation and processing water is possibly both an entrance and contamination pathway. Moreover, virulence and AMR genes were detected and phenotypic characterization was performed, additionally. Virulence factors such as prfA, hly, plcA, plcB, hpt, actA, inlA, inlB, and mpl were identified in pathogenic and nonpathogenic Listeria species. Besides, phenotypic resistance was detected against benzylpenicillin, fosfomycin and moxifloxacin in all eight L. monocytogenes isolates. Benzylpenicillin is a therapeutic agent against listeriosis and detected AMR is a cause of concern. L. innocua was the most resistant Listeria spp. next to L. seeligeri and L. newyorkensis in this study. In addition, 123 samples of fresh soft fruit and frozen berries were collected randomly from supermarkets across the south of Bavaria, Germany. Only one L. grayi isolate was detected in frozen blackberries, while all other samples were negative for Listeria spp. and L. monocytogenes. In conclusion, Listeria spp. and L. monocytogenes were present in FNAO primary production and processing companies in Bavaria, Germany. Environmental, irrigation and processing water samples showed high prevalences of Listeria spp. and L. monocytogenes. An external introduction by incoming raw material or irrigation and processing water is probable. Furthermore, plant-specific L. monocytogenes isolates in FNAO facilities are discussed. Good hygienic practice is crucial to avoid cross-contamination. The data determined in this study indicate that FNAO primary production and processing plants should be focusing more on L. monocytogenes. Listeria monitoring means continuous sampling of the environment, irrigation/processing water and food, and represents an important mechanism to resolve foodborne outbreaks.