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In this contribution, the antimicrobial susceptibility toward 11 antibiotics and four biocides of a panel of 205 Listeria monocytogenes (Lm) strains isolated from different ecological niches (i.e., food, animals and natural environment) was evaluated. The impact of exposure to biocides on the antibiotic susceptibilities of Lm was also investigated. Lm strains isolated from food exhib-ited overall a lower susceptibility (higher minimal inhibitory concentrations, MIC) for ammonium quaternary compounds (QACs) and peracetic acid (PAC) than strains isolated from animals and natural environments. Conversely, the ecological origins of Lm strains did not significantly affect their susceptibilities towards antibiotics. Interestingly, repeated exposure to QACs recurrently led to a decrease in susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human medicine. Moreover, these lower levels of susceptibility to CIP remained stable in most Lm strains even after subcultures without biocide selection pressure, suggesting an adaptation involving modifications at the genetic level. Results underlined the ability of Lm to adapt to biocides, especially QACs, and the potential link between this adaptation and the selection of resistance toward critical antibiotics such as ciprofloxacin. These data support a potential role of the extensive use of QACs from “farm to fork” in the selection of biocide and antibiotic resistance in pathogenic bacteria such as Lm.

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.

Resistance plasmids play a crucial role in the transfer of antimicrobial resistance from the veterinary sector to human healthcare. In this study plasmids from foodborne Escherichia coli isolates with a known (ES)BL or tetracycline resistance were sequenced entirely with short- and long-read technologies to obtain insight into their composition and to identify driving factors for spreading. Resistant foodborne E. coli isolates often contained several plasmids coding for resistance to various antimicrobials. Most plasmids were large and contained multiple resistance genes in addition to the selected resistance gene. The majority of plasmids belonged to the IncI, IncF and IncX incompatibility groups. Conserved and variable regions could be distinguished in each of the plasmid groups. Clusters containing resistance genes were located in the variable regions. Tetracycline and (extended spectrum) beta-lactamase resistance genes were each situated in separate clusters, but sulphonamide, macrolide and aminoglycoside formed one cluster and lincosamide and aminoglycoside another. In most plasmids, addiction systems were found to maintain presence in the cell.

In this contribution, the antimicrobial susceptibility toward 11 antibiotics and four biocides of a panel of 205 Listeria monocytogenes (Lm) strains isolated from different ecological niches (i.e., food, animals and natural environment) was evaluated. The impact of exposure to biocides on the antibiotic susceptibilities of Lm was also investigated. Lm strains isolated from food exhib-ited overall a lower susceptibility (higher minimal inhibitory concentrations, MIC) for ammonium quaternary compounds (QACs) and peracetic acid (PAC) than strains isolated from animals and natural environments. Conversely, the ecological origins of Lm strains did not significantly affect their susceptibilities towards antibiotics. Interestingly, repeated exposure to QACs recurrently led to a decrease in susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human medicine. Moreover, these lower levels of susceptibility to CIP remained stable in most Lm strains even after subcultures without biocide selection pressure, suggesting an adaptation involving modifications at the genetic level. Results underlined the ability of Lm to adapt to biocides, especially QACs, and the potential link between this adaptation and the selection of resistance toward critical antibiotics such as ciprofloxacin. These data support a potential role of the extensive use of QACs from “farm to fork” in the selection of biocide and antibiotic resistance in pathogenic bacteria such as Lm.

Genome mining of the bacterial strains Pseudomonas sp. SH-C52 and Pseudomonas fluorescens DSM 11579 showed that both strains contained a highly similar gene cluster encoding an octamodular nonribosomal peptide synthetase (NRPS) system which was not associated with a known secondary metabolite. Insertional mutagenesis of an NRPS component followed by comparative profiling led to the discovery of the corresponding novel linear octalipopeptide thanafactin A, which was subsequently isolated and its structure determined by two-dimensional NMR and further spectroscopic and chromatographic methods. In bioassays, thanafactin A exhibited weak protease inhibitory activity and was found to modulate swarming motility in a strain-specific manner.

The world market for food supplements is large and is driven by the claims of these products to, for example, treat obesity, increase focus and alertness, decrease appetite, decrease the need for sleep or reduce impulsivity. The use of illegal compounds in food supplements is a continuous threat, certainly because these compounds and products have not been tested for safety by competent authorities. It is therefore of the utmost importance for the competent authorities to know when new products are being marketed and to warn users against potential health risks. In this study, an approach is presented to detect new and unknown stimulants in food supplements using machine learning. More than 20 new stimulants were identified from two different data sources, namely scientific literature applying word embedding on > 2 million abstracts and articles from formal and social media on the world wide web using text mining. The results show that the developed approach may be suitable to detect “unknowns” in the emerging risk identification activities performed by the competent authorities, which is currently a major hurdle.

Contamination of bivalve molluscs with viruses is well recognized as a food safety risk. A microbiological criterion for norovirus (NoV) and hepatitis A virus (HAV) in shellfish, however, does not exist in the European Union currently. The aim of this study was to evaluate the contamination levels of these viruses for fluctuation over a long period (2013–2017) in oyster (n = 266) and mussel samples (n = 490) using a method based on ISO/TS 15216-1: 2013. Samples were taken at different points in the food chain, either directly post-harvest, at Dutch dispatch centers or in retail stores, from September until March of each year. Altogether, 53.1% of the mussel and 31.6% of the oyster samples tested positive for NoV RNA. Simultaneous presence of NoV GI and GII RNA was observed in 31.6% of mussel and 10.2% of oyster samples. Contamination levels in NoV positive mussel samples collected post-harvest from B-areas were significantly higher than in those collected post-harvest from A-areas, or at dispatch centers or retail stores. Levels in oysters from dispatch were significantly lower than those collected in retail stores. Ready for sale mussels and oysters contained 2.04 and 1.76 mean log10 transformed NoV genome copies/gram (gc/g), respectively. GII levels were at a constant level in ready for sale mussels throughout all sampling periods in the study. This seemed to be true for oysters as well. HAV RNA was detected in only one of the tested mussel samples (n = 392) (typed HAV 1A) and in none of the tested oyster samples (n = 228). Critical evaluation of NoV and HAV levels in shellfish can be of help for risk assessment and risk management actions.

The aim of the present study was to assess raw pork sausages collected on the Dutch market for the presence of hepatitis E virus (HEV) RNA. 46 of 316 (14.6%) products sampled from Dutch retail stores in 2017–2019 were positive for HEV RNA. HEV RNA was detected in 10.8% of “cervelaat” (n = 74), 18.5% of salami (n = 92), 26.1% of “metworst” (n = 46), 16.3% of “snijworst” (n = 43) samples. This was significantly more often than in other raw pork sausages like dried sausages, fuet or chorizo (3.3%, n = 61). The percentage of HEV RNA positive products was not significantly different for products sold as either sliced or unsliced deli meat. The average viral load in positive tested products was 2.76 log10 genome copies per 5 g, incidentally reaching up to 4.5 log10 genome copies per 5 g. The average HEV RNA level was significantly higher in samples collected in 2017 than those in samples collected in 2018, and most of the samples in 2019. Typing by sequence analysis was successful for 33 samples, all revealing genotype 3c. The results support recent epidemiological studies that identified specific raw pork sausages as risk factor for hepatitis E virus infection in the Netherlands. Persons at risk, including Dutch transplant recipients, have been advised to avoid the consumption of raw pork sausages. The study warrants a continuation of monitoring to follow the HEV RNA levels in pork products for use in risk assessments and risk management.

In 1999 startte de surveillance van shigatoxineproducerende Escherichia coli (STEC) in Nederland met de meldingen van STEC O157-infecties. In 2007 zijn STEC non-O157-infecties hieraan toegevoegd. Per juli 2016 is de focus van de STEC-surveillance verschoven naar acute en ernstige(re) infecties middels nieuwe meldingscriteria. In 2018 werden 488 patiënten met een STEC-infectie gemeld, waarvan 59 patiënten met een STEC O157-infectie, 87 met een STEC non-O157-infectie, waaronder 23 STEC O26, en 342 patiënten met STEC zonder verdere typering. 21 patiënten werden gemeld met hemolytisch-uremisch syndroom (HUS) (5x O157, 6x O26, 10x zonder informatie over O-typering). STEC O157 blijft daarmee het belangrijkste serotype in Nederland, gevolgd door STEC O26. Voor het vaststellen van mogelijke bronnen van infectie onderzoekt de Nederlandse Voedsel- en Warenautoriteit (NVWA) monsters van voedsel en landbouwhuisdieren op STEC. In de niet-humane isolaten werden voornamelijk STEC O146, O113, O38 en O91 aangetroffen. Door de overstap naar het gebruik van whole genome sequencing (WGS) voor alle STEC-isolaten, is de clusterdetectie versneld en verbeterd. Er werden in 2018 meerdere WGS-clusters van patiëntisolaten gezien, maar geen met zowel humane als voedselisolaten. Met de invoering van de nieuwe meldingscriteria is het aantal meldingen gedaald, maar stijgt het aandeel meldingen zonder isolaat. Dit vormt een bedreiging voor de surveillance, omdat het opsporen van een cluster zeer afhankelijk is van de beschikbaarheid van een STEC-typering, en de bevestiging van een cluster met WGS wordt gedaan.STEC is een bacterie die maag-darmklachten kan veroorzaken. De symptomen variëren van diarree tot hemorragische colitis en HUS. (1) STEC is een zoönose waarvan herkauwers, met name runderen, het belangrijkste reservoir zijn. (2) STEC-infecties zijn vaak het gevolg van de consumptie van besmet voedsel, maar transmissie via het milieu lijkt ook belangrijk. (2, 3) Acute STEC-infecties zijn meldingsplichtig volgens de Wet publieke gezondheid (Wpg), vanwege de ernst van de ziekte - vooral bij kleine kinderen en ouderen - en het risico op grootschalige uitbraken. In dit artikel presenteren we de resultaten van de surveillance voor het jaar 2018.

Sinds 2008 is listeriose meldingsplichtig. In 2018 zijn 78 patiënten met listeriose geregistreerd, waaronder 7 zwangere vrouwen (9%). Vier volwassenen zijn ten gevolge van de infectie overleden (6%). De meeste listeriosepatiënten hadden ernstig onderliggende aandoeningen en/of gebruikten immunosuppressiva en/of maagzuurremmers. Een aantal risicoproducten werden in 2018 vaker door patiënten geconsumeerd dan in voorgaande jaren. De meest opvallende stijgers zijn corned beef, gerookte zalm, garnalen en kibbeling/lekkerbek. Whole-genome-sequencing (WGS)-gegevens lieten een aantal clusteringen van patiëntisolaten zien en ook waren een aantal patiëntisolaten geclusterd met voedselisolaten. De meeste clusters bestaan uit patiënten uit verschillende jaren bij wie (vrijwel) identieke stammen zijn aangetoond. Er lijkt dus sprake te zijn van stammen die vanuit persisterende bronnen levensmiddelen besmetten. WGS maakt deze nieuwe inzichten mogelijk en biedt ook nieuwe mogelijkheden om de ziektelast van listeriose verder te verminderen vanwege het grotere vermogen om verbanden te leggen tussen de levensmiddelen en patiënten.Listeria monocytogenes is een bacterie die overal in het milieu voorkomt. De bacterie kan zelfs onder ongunstige omstandigheden zoals droogte en lage temperaturen, overleven en groeien. Infectie bij de mens gebeurt voornamelijk via voedsel dat besmet wordt vanuit de productieomgeving. Het aantal mensen dat listeriose oploopt is niet heel groot, maar de ziektelast is door de ernst van de ziekte hoog. (1, 2) In Nederland bestaat er sinds 2005 een laboratoriumsurveillance voor L. monocytogenes en een aangifteplicht sinds december 2008. Sinds 2017 wordt WGS toegepast als standaard typeringsmethode. Daarnaast worden door de Nederlandse Voedsel en Waren Autoriteit (NVWA) jaarlijks diverse risicovolle voedingsmiddelen op L. monocytogenes onderzocht. In deze rapportage presenteren we de gezamenlijke resultaten van 2018 en vergelijken die met elkaar en ten opzichte van voorgaande jaren.

In 1999 startte de surveillance van shigatoxineproducerende Escherichia coli (STEC) in Nederland met de meldingen van STEC O157-infecties. In 2007 zijn STEC non-O157-infecties hieraan toegevoegd. Per juli 2016 is de focus van de STEC-surveillance verschoven naar acute en ernstige(re) infecties middels nieuwe meldingscriteria. In 2018 werden 488 patiënten met een STEC-infectie gemeld, waarvan 59 patiënten met een STEC O157-infectie, 87 met een STEC non-O157-infectie, waaronder 23 STEC O26, en 342 patiënten met STEC zonder verdere typering. 21 patiënten werden gemeld met hemolytisch-uremisch syndroom (HUS) (5x O157, 6x O26, 10x zonder informatie over O-typering). STEC O157 blijft daarmee het belangrijkste serotype in Nederland, gevolgd door STEC O26. Voor het vaststellen van mogelijke bronnen van infectie onderzoekt de Nederlandse Voedsel- en Warenautoriteit (NVWA) monsters van voedsel en landbouwhuisdieren op STEC. In de niet-humane isolaten werden voornamelijk STEC O146, O113, O38 en O91 aangetroffen. Door de overstap naar het gebruik van whole genome sequencing (WGS) voor alle STEC-isolaten, is de clusterdetectie versneld en verbeterd. Er werden in 2018 meerdere WGS-clusters van patiëntisolaten gezien, maar geen met zowel humane als voedselisolaten. Met de invoering van de nieuwe meldingscriteria is het aantal meldingen gedaald, maar stijgt het aandeel meldingen zonder isolaat. Dit vormt een bedreiging voor de surveillance, omdat het opsporen van een cluster zeer afhankelijk is van de beschikbaarheid van een STEC-typering, en de bevestiging van een cluster met WGS wordt gedaan.STEC is een bacterie die maag-darmklachten kan veroorzaken. De symptomen variëren van diarree tot hemorragische colitis en HUS. (1) STEC is een zoönose waarvan herkauwers, met name runderen, het belangrijkste reservoir zijn. (2) STEC-infecties zijn vaak het gevolg van de consumptie van besmet voedsel, maar transmissie via het milieu lijkt ook belangrijk. (2, 3) Acute STEC-infecties zijn meldingsplichtig volgens de Wet publieke gezondheid (Wpg), vanwege de ernst van de ziekte - vooral bij kleine kinderen en ouderen - en het risico op grootschalige uitbraken. In dit artikel presenteren we de resultaten van de surveillance voor het jaar 2018.

Food for human consumption is screened widely for the presence of antibiotic-resistant bacteria to assess the potential for transfer of resistant bacteria to the general population. Here, we describe an Enterobacter cloacae complex isolated from imported seafood that encodes two carbapenemases on two distinct plasmids., Food for human consumption is screened widely for the presence of antibiotic-resistant bacteria to assess the potential for transfer of resistant bacteria to the general population. Here, we describe an Enterobacter cloacae complex isolated from imported seafood that encodes two carbapenemases on two distinct plasmids. Both enzymes belong to Ambler class A β-lactamases, the previously described IMI-2 and a novel family designated FLC-1. The hydrolytic activity of the novel enzyme against aminopenicillins, cephalosporins, and carbapenems was determined.

A multiplex quantitative PCR (qPCR) was developed and evaluated for the simultaneous detection of Salmonella spp., S. enterica serovar Typhimurium and S. enterica serovar Enteritidis in various (food) matrices. Early and fast detection of these pathogens facilitates effective intervention and prevents further distribution of contaminated food products on the market. Three primer and probe sets were designed to target the invA gene, the STM4200 gene, and the SEN1392 gene to detect and differentiate Salmonella spp., S. Typhimurium, and S. Enteritidis, respectively. The multiplex qPCR targeting these three genes was optimized for efficiency and linearity. By testing 225 Salmonella isolates and 34 non-Salmonella isolates from various sources the inclusivity and exclusivity were determined. The inclusivity of the multiplex qPCR was 100% for all Salmonella isolates, including 72 S. Typhimurium isolates, and 53 S. Enteritidis isolates. The exclusivity for Salmonella spp., S. Typhimurium, and S. Enteritidis was 100%, 94.6%, and 100%, respectively. No positive results were reported for non-Salmonella isolates. The limit of detection (LOD) for the qPCR was determined for the matrices poultry, minced meat, egg, herbs/spices, powdered milk, fish, animal feed, boot-socks with chicken feces and chicken down. LOD values for qPCR and the conventional culture methods were similar, except for the matrix boot-socks and down, for which the LOD for the conventional culture methods performed better than the qPCR method. In conclusion, the multiplex qPCR assay developed allows for rapid screening of Salmonella spp., S. Typhimurium, and S. Enteritidis in various (food) matrices.

Enterobacter hormaechei 3442 encoding blaFLC-1 and blaIMI-2