Slaughter pigs as carrier of Listeria monocytogenes in Germany

Listeria (L.) monocytogenes as the cause of human listeriosis is widespread in the environment and a hazard considering food safety. Almost all animal species as well as humans can be asymptomatic carriers of this bacterium. In pigs, the tonsils are identified as the organ with the highest detection rate compared to other sample matrices. We sampled 430 pigs in total in two slaughterhouses in Northwest and East Germany, two structurally different and important regions in pig production, to re-examine pigs as a possible source of Listeria-contamination of pork products. We detected a low prevalence of L. monocytogenes in tonsil samples of 1.6% (7/430) on single animal level and of 11.6% (5/43) on herd level with no significant difference between the two German regions. Apart from L. monocytogenes, the usually non-pathogenic L. innocua had a prevalence of 1.2% (5/430) on single animal level. From 200 pigs from Northwest Germany, intestinal content samples were analysed in addition to tonsil samples from the same animals, but no positive sample was found for L. monocytogenes (0.0%, 0/200), while four pigs were positive for L. innocua (2.0%, 4/200). Although the prevalence of L. monocytogenes in tonsils is low, the risk of cross-contaminating meat with the pathogen is still given

Hepatitis E virus cross-contamination on the surface of porcine livers after storage in Euro meat containers in a German pig abattoir

Hepatitis E virus (HEV) is a foodborne zoonotic pathogen and known as the causative agent of hepatitis E in humans. The specific role of porcine liver as a vehicle for human HEV infections has been highlighted in different studies. Nevertheless, gaps of knowledge still exist regarding possible HEV cross-contamination both at consumer and production level. Furthermore, people working in the food production industry, e.g. veterinarians and abattoir employees, are exposed to an increased risk of HEV infection. The aim of the present study was to investigate HEV cross-contamination on the surface of porcine liver in a German abattoir. The sample set included 250 samples of porcine liver parenchyma and the corresponding 250 superficial layer samples of the same livers, which were analyzed for the presence of HEV ribonucleic acid (RNA). Afterwards, the initial status of the tested liver parenchyma was compared with the occurrence of HEV RNA in the corresponding superficial layer. HEV RNA was detectable in 34% (85/250) of superficial layer samples, with 58% (49/85) of the samples originated from initially HEV negative livers. To our knowledge, this is the first study that provides an insight in the potential of HEV cross-contamination at abattoir level in Germany. Furthermore, it could be identified that the joint storage of livers in Euro meat containers has a significant impact on the presence of HEV RNA on the surface of porcine liver

Food chain information for broilers: Results of a Europe-wide survey on status quo, usability and suggestions for improvement

A modern risk-based meat safety assurance system (RB-MSAS) for poultry includes information systems to better adapt to risks for meat safety. Food Chain Information (FCI) according to Regulation (EC) No 853/2004 includes data on animal health, laboratory test results and further information that is relevant for consumer protection. FCI has to be transferred from the farm to the abattoir where the data analysis leads to adaptations of the slaughter process and/or meat inspection. As the EU regulation describes the required FCI imprecisely and without recommendations for meaningful reactions to specific information, implementation differs between European countries and even between abattoirs within one country. To assess the status quo of transfer, use and the usefulness of FCI in Europe, we conducted a survey on FCI for broilers among European stakeholders. The answers of 32 respondents, working in 14 different European countries as official veterinarians/meat inspection officers, food business operators/quality assurance managers, or in other positions in broiler meat hygiene, were included in the analysis. Overall, 75% (24/32) of the respondents stated they find FCI helpful for decision-making. All respondents (56%, 18/32) with electronic access to FCI find the transmission procedure practical. Most respondents get information about previous ante-mortem (81%, 26/32) and post-mortem (91%, 29/32) inspection results for flocks from the same holding of provenance. Likewise, most respondents receive data on mortality rate (88%, 28/32) and veterinary medications with a withdrawal period that have been administered during the fattening period (84%, 27/32). Overall, 53% of the respondents indicated that the entire fattening period would be the optimal relevant period for recording the administration of veterinary medications with a withdrawal period. In addition to this information, the respondents desired to have more data about further treatment (28%, 9/32) and data from the private veterinarian responsible for the farm (25%, 8/32). Knowledge of these data especially led to various measures being initiated at the abattoir, according to the respondents. In contrast, some specific production data were reported as also an important part of FCI, even though these data have little impact on the measures to protect human health that are taken in the slaughter process or at post-mortem inspection. All respondents transferred information about findings in the abattoir back to the farmers: these data were ante-mortem (72%, 23/32) and post-mortem (100%, 32/32) inspection results as well as further information (28%, 6/32). Our study shows that FCI for broilers is already widely successfully established as part of the RB-MSAS in Europe. Important information, like the ante- and post-mortem inspection results, is mostly available. Recommendations for improvement and for data to be included based on our study and literature are, inter alia: electronic data transfer; on-farm mortality; diseases occurring on-farm, especially those shortly before slaughter; all data on treatment with veterinary medications; EFSA's harmonised epidemiological indicators and; specific production data. Further studies are needed to gain a deeper understanding of correlations between ante-mortem data for the flock and findings at post-mortem inspection. Specific measures to be taken as a result of incoming information need to be stipulated in order that FCI is used more efficiently as a risk assessment tool in RB-MSAS

The microbiological and sensory status of dual-purpose chickens (Lohmann Dual), male Lohmann Brown Plus chickens, and conventional laying hens slaughtered in a laying hen abattoir compared to conventional broilers slaughtered in a broiler abattoir

Alternatives to conventional chicken meat and egg production are increasingly under discussion, especially because of the common practice of killing male day-old chicks from laying lines which has been banned from the beginning of 2022 in Germany and is planned to be banned during 2022 in other countries. Production of dual-purpose chicken lines is one possible solution, as such lines combine moderate laying and growth performance. The microbiological status of products from such breeds must be comparable to existing products on the market for food safety purposes. Additionally, the production of such products will take longer because of the feeding regimes required, and again, comparability should be safeguarded for the best consumer protection. The dual-purpose chicken line, Lohmann Dual (males), was compared to males from the laying line Lohmann Brown Plus, conventional laying hens (all slaughtered and processed in the same conventional laying hen abattoir), and conventional broilers (slaughtered in a conventional broiler abattoir). Neck skin samples were taken before chilling at the end of each slaughter line to determine the microbial status of the carcasses. Additionally, fresh and cooked meat sensory analysis was performed on meat from broilers and male and female Lohmann Dual and Lohmann Brown Plus chickens (for three carcasses of each group) at the German Agricultural Society Test Center in Kassel. The focus was on the performance of male Lohmann Dual compared to the other lines. There was no difference in the Enterobacteriaceae count of the dual-purpose chicken line compared to conventional broilers, whereas laying hens had a significantly higher microbial load before chilling, as based on neck skin examinations (p<0.001). According to sensory test results, the meat from dual-purpose chickens was the best (as no defects were found) among the five chicken meat types examined. In conclusion, based on their microbial status and sensory analysis of fresh and cooked meat, Lohmann Dual males slaughtered in a laying hen abattoir can be considered as an alternative to conventionally kept broilers slaughtered in a broiler abattoir

Distribution and Characteristics of Listeria spp. in Pigs and Pork Production Chains in Germany

Listeria (L.) monocytogenes is a foodborne pathogen that can cause disease, mainly in elderly, pregnant or immunocompromised persons through consumption of contaminated food, including pork products. It is widespread in the environment and can also be found in asymptomatic carrier animals, for example, in different tissues of pigs. To learn more about their nature, 16 Listeria spp. isolates found in tonsils and intestinal content of pigs and 13 isolates from the slaughterhouse environment were characterized using next-generation sequencing (NGS). A wide distribution of clonal complexes was observed in pigs, as well as in the pork production chain, suggesting multiple sources of entry. Hypervirulent clones were found in pig tonsils, showing the potential risk of pigs as source of isolates causing human disease. The presence of closely related isolates along the production chain suggests a cross-contamination in the slaughterhouse or recontamination from the same source, strengthening the importance of efficient cleaning and disinfection procedures. The phenotypical antimicrobial resistance status of L. monocytogenes isolates was examined via broth microdilution and revealed a low resistance level. Nevertheless, genotypical resistance data suggested multiple resistances in some non-pathogenic L. innocua isolates from pig samples, which might pose a risk of spreading resistances to pathogenic species

Examination on the introduction of Listeria monocytogenes into the food chain via slaughter pigs

Das Gram-positive Bakterium L. monocytogenes ist der wichtigste Erreger der humanen Listeriose. Betroffen von der invasiven Form sind hauptsächlich sehr junge, alte, immunsuppressive und schwangere Personen. Eine Infektion entsteht vorwiegend über den Verzehr sogenannter ready-to-eat Produkte. Schweinefleisch wurde als Ursache für mehrere Ausbrüche bzw. Krankheitsfälle festgestellt. Es kann während der Schlachtung, Verarbeitung und Produktion mit dem ubiquitär vorkommenden Bakterium kontaminiert werden. Schweine können aber auch in der Primärproduktion damit in Kontakt kommen und das Pathogen als asymptomatische Trägertiere mit in den Schlachtbetrieb bringen. In dieser Arbeit wurden 430 Schlachtschweine zweier deutscher Schweineschlachtbetriebe auf das Vorhandensein von Listerien untersucht. Dabei betrug die ermittelte Prävalenz an L. monocytogenes auf Einzeltierebene 1,6% (7/430) der Tonsillenproben, was 11,6% positiven Herden entsprach, wobei kein signifikanter Unterschied zwischen den beiden untersuchten Regionen in Deutschland, dem Nordwesten und dem Osten, als Herkunft der Schweine festgestellt wurde. Die Prävalenz der apathogenen Spezies L. innocua lag auf Einzeltierebene bei 1,2% (5/430). Zusätzlich wurden Proben aus der Schlachtumgebung entnommen. Insgesamt 29 Listeria spp.-Isolate wurden mithilfe von NGS weiter untersucht, sowie die phänotypischen antimikrobiellen Resistenzen der 14 L. monocytogenes-Isolate mittels Bouillon-Mikrodilutionsverfahren ermittelt. Unter den Isolaten wurden sowohl im Schwein als auch der Umgebung viele unterschiedliche CCs vorgefunden und nur fünf der 29 Isolate als eng verwandt eingestuft, was für mehrere verschiedene Eintragsquellen spricht. So wurden hypervirulente CCs, die mit humanen Erkrankungen in Verbindung gebracht wurden, in Tonsillenproben sowie in Umgebungsproben gefunden, was das Schwein als potenzielle Eintragsquelle humanpathogener Isolate bestätigt und die Wichtigkeit der Einhaltung einer guten Hygienepraxis im Schlachtprozess unterstreicht. Der Nachweis der eng verwandten Isolate entlang der Zerlegungs- und Verarbeitungskette deutet auf eine Kreuzkontamination innerhalb des Betriebs oder Rekontamination aus derselben Quelle hin und unterstreicht die Durchführung einer effizienten Reinigung und Desinfektion. Die Analyse der antimikrobiellen Resistenzen zeigt in den L. monocytogenes-Isolaten nur bereits bekannte, intrinsische Resistenzen. Unter den L. innocua-Isolaten wurden jedoch zusätzlich weitere Resistenzgene gefunden, am häufigsten gegenüber Tetrazyklinen. Jene Isolate mit multiplen genotypischen Resistenzen stammten aus Proben vom Schwein, was einen Zusammenhang mit dem Antibiotikaeinsatz in der Schweineproduktion vermuten lässt. Auch wenn die apathogene Spezies L. innocua keine direkte Gefahr als Krankheitserreger darstellt, kann sie als Reservoir für Resistenzgene diese an pathogene Spezies durch horizontalen Gentransfer weitergeben. Die Überwachung des Vorkommens von L. monocytogenes in Lebensmitteln sowie der Resistenzsituation von Listeria spp. ist ebenso wie eine gute Hygienepraxis entlang der gesamten Lebensmittelkette bis hin zur Aufklärung des Konsumenten und Forschung an zukünftigen Bekämpfungsstrategien im Sinne des One-Health-Konzepts wichtig für die Erhaltung der öffentlichen Gesundheit

Comparative Study of Fresh and Frozen Broiler Neck Skin Sampled for Process Hygiene Purposes

The objective of the study was to determine the effect of freezing broiler neck skin samples before their microbial analysis, compared to freshly examined samples regarding total viable count (TVC) and Enterobacteriaceae count (EC). For this, 300 neck skin samples were taken at a German commercial broiler abattoir and each neck skin sample was cut into two parts. One randomly selected part underwent microbial examination after storage at 4 °C overnight; the other part was frozen at −30 °C for eight weeks before analysis in the same laboratory. Log cfu/g values of TVC and EC were separately compared between the fresh and frozen neck skin samples. A difference up to 0.5 log values was set as acceptable, i.e., fresh and frozen samples with counts that differed by this amount were considered as not different. The differences between the grouped samples of fresh and frozen broiler neck skin regarding both TVC and EC levels were less than 0.5 log values. Thus, it can be assumed that broiler neck skin samples, both fresh and frozen for eight weeks, are suitable for microbiological examination, as the TVC and EC results showed equivalence. Therefore, freezing broiler neck skin samples can be an option to maintain viable bacteria levels in broiler neck skin samples taken for microbiological examination in process control, when freezing and later examination is necessary due to insufficient laboratory capacity for the examination of fresh neck skin samples

A European-wide dataset to uncover adaptive traits of Listeria monocytogenes to diverse ecological niches

Listeria monocytogenes (Lm) is a ubiquitous bacterium that causes listeriosis, a serious foodborne illness. In the nature-to-human transmission route, Lm can prosper in various ecological niches. Soil and decaying organic matter are its primary reservoirs. Certain clonal complexes (CCs) are over-represented in food production and represent a challenge to food safety. To gain new understanding of Lm adaptation mechanisms in food, the genetic background of strains found in animals and environment should be investigated in comparison to that of food strains. Twenty-one partners, including food, environment, veterinary and public health laboratories, constructed a dataset of 1484 genomes originating from Lm strains collected in 19 European countries. This dataset encompasses a large number of CCs occurring worldwide, covers many diverse habitats and is balanced between ecological compartments and geographic regions. The dataset presented here will contribute to improve our understanding of Lm ecology and should aid in the surveillance of Lm. This dataset provides a basis for the discovery of the genetic traits underlying Lm adaptation to different ecological niches

A European-wide dataset to uncover adaptive traits of Listeria monocytogenes to diverse ecological niches

International audienceListeria monocytogenes ( Lm ) is a ubiquitous bacterium that causes listeriosis, a serious foodborne illness. In the nature-to-human transmission route, Lm can prosper in various ecological niches. Soil and decaying organic matter are its primary reservoirs. Certain clonal complexes (CCs) are over-represented in food production and represent a challenge to food safety. To gain new understanding of Lm adaptation mechanisms in food, the genetic background of strains found in animals and environment should be investigated in comparison to that of food strains. Twenty-one partners, including food, environment, veterinary and public health laboratories, constructed a dataset of 1484 genomes originating from Lm strains collected in 19 European countries. This dataset encompasses a large number of CCs occurring worldwide, covers many diverse habitats and is balanced between ecological compartments and geographic regions. The dataset presented here will contribute to improve our understanding of Lm ecology and should aid in the surveillance of Lm . This dataset provides a basis for the discovery of the genetic traits underlying Lm adaptation to different ecological niches