Mapping the Kitchen Microbiota in Five European Countries Reveals a Set of Core Bacteria across Countries, Kitchen Surfaces, and Cleaning Utensils

The residential kitchen is often heavily colonized by microbes originating from different sources, including food and human contact. Although a few studies have reported the bacterial composition in cleaning utensils and surface samples there is limited knowledge of the bacterial diversity across different sample types, households, and countries. As part of a large European study, we have identified the microbiota of 302 samples from cleaning utensils (sponges and cloths), kitchen surfaces (sinks, cutting boards, countertops, tap handles, and a pooled sample of other handles) in 74 households across 5 countries (France, Hungary, Norway, Portugal, and Romania). In total, 31 bacterial phyla were identified, with Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria being the most abundant. Despite large variations in households with respect to kitchen standards, kitchen practices, cleaning regimes, and diet and considerable differences in bacterial diversity between samples, eight bacterial genera/families commonly associated with environmental sources were identified in most samples and defined as a core microbiota: Acinetobacter, Pseudomonas, Enhydrobacter, Enterobacteriaceae, Psychrobacter, Chryseobacterium, Bacillus, and Staphylococcus. These genera/families were also among the bacteria with the highest relative abundance across all samples, in addition to Yersiniaceae, Kocuria, Pantoea, and Streptococcus. Taxa associated with potential pathogens and fecal indicators were low in abundance but broadly distributed throughout the households. The microbial composition of surface samples indicated that the microbial composition on kitchen surfaces is more characteristic for the particular country than the object type, while the microbiota of cleaning utensils was similar across countries but differed between types (sponge or cloth).publishedVersio

Survival potential of wild type cellulose deficient Salmonella from the feed industry

<p>Abstract</p> <p>Background</p> <p>Biofilm has been shown to be one way for <it>Salmonella </it>to persist in the feed factory environment. Matrix components, such as fimbriae and cellulose, have been suggested to play an important role in the survival of <it>Salmonella </it>in the environment. Multicellular behaviour by <it>Salmonella </it>is often categorized according to colony morphology into rdar (red, dry and rough) expressing curli fimbriae and cellulose, bdar (brown, dry and rough) expressing curli fimbriae and pdar (pink, dry and rough) expressing cellulose.</p> <p>The aim of the study was to look into the distribution of morphotypes among feed and fish meal factory strains of <it>Salmonella</it>, with emphasis on potential differences between morphotypes with regards to survival in the feed factory environment.</p> <p>Results</p> <p>When screening a total of 148 <it>Salmonella </it>ser. Agona, <it>Salmonella </it>ser. Montevideo, <it>Salmonella </it>ser. Senftenberg and <it>Salmonella </it>ser. Typhimurium strains of feed factory, human clinical and reference collection origin, as many as 99% were able to express rough morphology (rdar or bdar). The dominant morphotype was rdar (74%), however as many as 55% of <it>Salmonella </it>ser. Agona and 19% of <it>Salmonella </it>ser. Senftenberg displayed the bdar morphology.</p> <p>Inconsistency in Calcofluor binding, indicating expression of cellulose, was found among 25% of all the strains tested, however <it>Salmonella </it>ser. Agona showed to be highly consistent in Calcofluor binding (98%).</p> <p>In biofilm, <it>Salmonella </it>ser. Agona strains with bdar mophology was found to be equally tolerant to disinfection treatment as strains with rdar morphotype. However, rdar morphology appeared to be favourable in long term survival in biofilm in a very dry environment.</p> <p>Chemical analysis showed no major differences in polysaccharide content between bdar and rdar strains. Our results indicate that cellulose is not a major component of the <it>Salmonella </it>biofilm matrix.</p> <p>Conclusion</p> <p>The bdar morphotype is common among <it>Salmonella </it>ser. Agona strains isolated from the factory environment. The rdar and the bdar strains were found to be equally tolerant to disinfectants, while the rdar strain was found to be more tolerant to long-term desiccation and nutrient depletion in biofilm than the bdar strain. Cellulose does not appear to be a major component of the <it>Salmonella </it>biofilm matrix.</p

Biofilm forming abilities of Salmonella are correlated with persistence in fish meal- and feed factories

<p>Abstract</p> <p>Background</p> <p>Feed contaminated with <it>Salmonella </it>spp. constitutes a risk of <it>Salmonella </it>infections in animals, and subsequently in the consumers of animal products. <it>Salmonella </it>are occasionally isolated from the feed factory environment and some clones of <it>Salmonella </it>persist in the factory environment for several years. One hypothesis is that biofilm formation facilitates persistence by protecting bacteria against environmental stress, e.g. disinfection. The aim of this study was to investigate the biofilm forming potential of <it>Salmonella </it>strains from feed- and fishmeal factories. The study included 111 <it>Salmonella </it>strains isolated from Norwegian feed and fish meal factories in the period 1991–2006 of serovar Agona, serovar Montevideo, serovar Senftenberg and serovar Typhimurium.</p> <p>Results</p> <p>Significant differences were found between serovars regarding the abilities to form biofilm on polystyrene (microtiter plate assay) and in the air-liquid interface of nutrient broth (pellicle assay). Strains of serovar Agona and serovar Montevideo were good biofilm producers. In Norwegian factories, clones of these serovars have been observed to persist for several years. Most serovar Senftenberg clones appear to persist for a shorter period, and strains of this serovar were medium biofilm producers in our test systems. Strains of the serovar Typhimurium were relatively poor biofilm producers. <it>Salmonella </it>ser. Typhimurium clones have not been observed to persist even though this serovar is resident in Norwegian wild life. When classifying strains according to persistence or presumed non-persistence, persistent strains produced more biofilm than presumed non-persisting strains.</p> <p>Conclusion</p> <p>The results indicate a correlation between persistence and biofilm formation which suggests that biofilm forming ability may be an important factor for persistence of <it>Salmonella </it>in the factory environment.</p

Kitchen cloths: Consumer practices, drying properties and bacterial growth and survival

Kitchen cloths have an important role in maintaining kitchen surfaces hygienically clean but may also act as vehicles for cross contamination of pathogens from food spills to hands and other foods. The aim of the present study was to map consumer practices across Europe and identify main factors that may contribute to unsafe use of kitchen cloths, such as type of cloth and storage practices. Consumer practices related to cloths were investigated in a web-based survey (N = 2394), while drying properties and growth and survival of Salmonella, Campylobacter and non-pathogenic food associated bacteria in inoculated cloths were studied in laboratory tests mimicking consumer practices. Among consumers in six European countries, cotton and microfiber cloths were reported to be the most used cloth types for cleaning food preparation areas and wiping up spills. . Fifty-seven percent of the consumers reportedly hang the cloth to dry after use. A large majority (72%) changed their cloths at regular times, with an average reported frequency of every 6 days. Large variations in water absorption (63–201 g) and drying rate (31.8–99.8% water loss after 4.5 h) among 17 types of commercially available cloths were found. Hanged up cloths dried faster than cloths stored crumpled as balls. Salmonella multiplied in all types of new cloths that were not hung to dry (crumpled), but about 3 log reduction or more were found after hanging cloths to dry for 24 h. For cloths collected from consumers, growth of inoculated Salmonella was not observed, but hanging the cloths resulted in more than 3 log reduction in numbers. A large variation in survival of Campylobacter was found depending on the type of cloth, but more than 5 log reduction was found after 24 h in all hanging cloths. A polypropylene and a viscose cloth with low water uptake and fast drying appeared to be the safest choice with a rapid reduction of both pathogens when hung (respectively 2 log and >6 log reduction for Salmonella and Campylobacter after 4.5 h) and reduction of Campylobacter when stored crumpled. The least safe cloth regarding pathogen growth and survival was a knitted cotton cloth with high water uptake and slow drying. There was no systematic difference in growth and survival of bacteria between microfiber cloths and cloths of other materials, nor between cloths with and without antimicrobial compounds. The present study shows that 16% of consumers have practices that would allow pathogens to contaminate, grow and survive in cloths until the next use. Touching and using these cloths can lead to contamination of hands and food contact surfaces, and potentially to ingestion of pathogens. Consumers should be advised to change cloths after using them for meat spills, but also to choose cloths that dry fast and keep them hanging to dry between use.publishedVersio

Micro ecosystems from feed industry surfaces: a survival and biofilm study of Salmonella versus host resident flora strains

<p>Abstract</p> <p>Background</p> <p>The presence of <it>Salmonella </it>enterica serovars in feed ingredients, products and processing facilities is a well recognized problem worldwide. In Norwegian feed factories, strict control measures are implemented to avoid establishment and spreading of <it>Salmonella </it>throughout the processing chain. There is limited knowledge on the presence and survival of the resident microflora in feed production plants. Information on interactions between <it>Salmonella </it>and other bacteria in feed production plants and how they affect survival and biofilm formation of <it>Salmonella </it>is also limited. The aim of this study was to identify resident microbiota found in feed production environments, and to compare the survival of resident flora strains and <it>Salmonella </it>to stress factors typically found in feed processing environments. Moreover, the role of dominant resident flora strains in the biofilm development of <it>Salmonella </it>was determined.</p> <p>Results</p> <p>Surface microflora characterization from two feed productions plants, by means of 16 S rDNA sequencing, revealed a wide diversity of bacteria. Survival, disinfection and biofilm formation experiments were conducted on selected dominant resident flora strains and <it>Salmonella</it>. Results showed higher survival properties by resident flora isolates for desiccation, and disinfection compared to <it>Salmonella </it>isolates. Dual-species biofilms favored <it>Salmonella </it>growth compared to <it>Salmonella </it>in mono-species biofilms, with biovolume increases of 2.8-fold and 3.2-fold in the presence of <it>Staphylococcus </it>and <it>Pseudomonas</it>, respectively.</p> <p>Conclusions</p> <p>These results offer an overview of the microflora composition found in feed industry processing environments, their survival under relevant stresses and their potential effect on biofilm formation in the presence of <it>Salmonella</it>. Eliminating the establishment of resident flora isolates in feed industry surfaces is therefore of interest for impeding conditions for <it>Salmonella </it>colonization and growth on feed industry surfaces. In-depth investigations are still needed to determine whether resident flora has a definite role in the persistence of <it>Salmonella </it>in feed processing environments.</p

Whole-Genome Sequencing Analysis of Listeria monocytogenes from Rural, Urban, and Farm Environments in Norway: Genetic Diversity, Persistence, and Relation to Clinical and Food Isolates

Listeria monocytogenes is a ubiquitous environmental bacterium associated with a wide variety of natural and human-made environments, such as soil, vegetation, livestock, food processing environments, and urban areas. It is also among the deadliest foodborne pathogens, and knowledge about its presence and diversity in potential sources is crucial to effectively track and control it in the food chain. Isolation of L. monocytogenes from various rural and urban environments showed higher prevalence in agricultural and urban developments than in forest or mountain areas, and that detection was positively associated with rainfall. Whole-genome sequencing (WGS) was performed for the collected isolates and for L. monocytogenes from Norwegian dairy farms and slugs (218 isolates in total). The data were compared to available data sets from clinical and food-associated sources in Norway collected within the last decade. Multiple examples of clusters of isolates with 0 to 8 whole-genome multilocus sequence typing (wgMLST) allelic differences were collected over time in the same location, demonstrating persistence of L. monocytogenes in natural, urban, and farm environments. Furthermore, several clusters with 6 to 20 wgMLST allelic differences containing isolates collected across different locations, times, and habitats were identified, including nine clusters harboring clinical isolates. The most ubiquitous clones found in soil and other natural and animal ecosystems (CC91, CC11, and CC37) were distinct from clones predominating among both clinical (CC7, CC121, and CC1) and food (CC9, CC121, CC7, and CC8) isolates. The analyses indicated that ST91 was more prevalent in Norway than other countries and revealed a high proportion of the hypovirulent ST121 among Norwegian clinical cases.publishedVersio

Pervasive Listeria monocytogenes is common in the Norwegian food system and is associated with increased prevalence of stress survival and resistance determinants

To investigate the diversity, distribution, persistence, and prevalence of stress survival and resistance genes of Listeria monocytogenes clones dominating in food processing environments in Norway, genome sequences from 769 L. monocytogenes isolates from food industry environments, foods, and raw materials (512 of which were sequenced in the present study) were subjected to whole-genome multilocus sequence typing (wgMLST), single-nucleotide polymorphism (SNP), and comparative genomic analyses. The data set comprised isolates from nine meat and six salmon processing facilities in Norway collected over a period of three decades. The most prevalent clonal complex (CC) was CC121, found in 10 factories, followed by CC7, CC8, and CC9, found in 7 factories each. Overall, 72% of the isolates were classified as persistent, showing 20 or fewer wgMLST allelic differences toward an isolate found in the same factory in a different calendar year. Moreover, over half of the isolates (56%) showed this level of genetic similarity toward an isolate collected from a different food processing facility. These were designated as pervasive strains, defined as clusters with the same level of genetic similarity as persistent strains but isolated from different factories. The prevalence of genetic determinants associated with increased survival in food processing environments, including heavy metal and biocide resistance determinants, stress response genes, and inlA truncation mutations, showed a highly significant increase among pervasive isolates but not among persistent isolates. Furthermore, these genes were significantly more prevalent among the isolates from food processing environments compared to in isolates from natural and rural environments (n = 218) and clinical isolates (n = 111) from NorwaypublishedVersio

Safe week, unsafe weekend? Consumers’ self-reported food safety practices and stomach sickness in cabin environments of varying infrastructure levels

Food poisoning is a threat to health and economy across regions and living standards, with an estimated 600 million cases worldwide every year. In consumer households, water and electricity facilities are key to safe food preparation and storage. However, recreational home environments may be of lower standard and expose dwellers to higher risk of foodborne illness. The aim of this study was to assess risk behaviours in Norwegian cabin kitchens in relation to the level of cabin infrastructure and compared to home practices. Cabin dwellers (N = 339) answered an online questionnaire about infrastructure, appliances, cleaning routines, and food habits at the cabin and at home. Correspondence analysis was used to define three cabin types of low (16%), medium (31%) and high (53%) infrastructure. The cabin types were compared to one another as well as to home in terms of cabin visit frequency and length, kitchen equipment, cleaning practices, food consumption, and incidence of stomach sickness. Consumer practices were evaluated for their impact on potential exposure to foodborne pathogens in light of the food safety situation and recommendations in Norway. Large variations in cabin kitchen equipment were found, where 35% of the respondents did not have running water in the kitchen and 18% did not have a refrigerator. The lack of running water and/or electrical appliances in cabins appeared to lead to adaptive consumer practices regarding hygiene routines (e.g., more hand disinfectant). Food consumption differed from home towards safer choices in all cabin types (e.g., less raw chicken and more canned foods). The estimated incidence rate of stomach sickness was of 4‰ occurrences per day at the cabin. Across cabin types, the incidence rate was 4.0 times larger in low-infrastructure cabins and 3.1 times larger in medium-infrastructure cabins compared to high-infrastructure cabins. The results uncover a need for information campaigns on the elevated risk for foodborne illness in cabin environments and how consumers should change practices to reduce the risk.publishedVersio

Assessment of ATP-Bioluminescence and Dipslide Sampling to Determine the Efficacy of Slaughterhouse Cleaning and Disinfection Compared with Total Aerobic and<i> Enterobacterales</i> Counts

Inadequate cleaning and disinfection (C&D) in slaughterhouses can cause bacterial contamination of meat, resulting in foodborne disease and reduced meat quality. Different methods for monitoring the efficacy of C&D procedures are available, but few studies have assessed their reliability. This study examined C&D efficacy in slaughterhouses and evaluated the diagnostic performance of methods for measuring surface hygiene.One red meat and one poultry slaughterhouse in Sweden were each visited on six occasions before and six occasions after C&D. Sampling points were sampled with: swabbing and plating for total aerobic bacteria (TAB) and Enterobacterales (EB); dipslides for total viable count; and ATP-bioluminescence tests. To evaluate the diagnostic performance of the dipslide and ATP-bioluminescence methods, the results were compared with (TAB) as a reference.In total, 626 samples were collected. For the majority of samples, TAB was lower after than before C&D and EB were mainly detected before C&D, indicating C&D efficacy. Greater reductions in mean TAB were observed in processing areas (2.2 and 2.8 log CFU/100 cm2 in red meat and poultry slaughterhouse, respectively) than in slaughter areas (1.3 log CFU/100 cm2 in both slaughterhouses). Approximately half of all samples were assessed as non acceptably clean (52% for red meat and 46% for poultry slaughterhouse) according to previously published thresholds. Critical food contact surfaces that were insufficiently cleaned and disinfected were plucking fingers, shackles, and a post-dehairing table. Cleaning and disinfection of drains and floors were inadequate.The ATP-bioluminescence method showed low specificity compared with the reference (TAB) in both the red meat (0.30) and poultry slaughterhouses (0.64). The sensitivity of dipslides was low (0.26) in the red meat slaughterhouse compared with TAB. A combination of ATP-bioluminescence and dipslides could provide more accurate estimates of C&D efficacy

Deciphering the virulence potential of Listeria monocytogenes in the Norwegian meat and salmon processing industry by combining whole genome sequencing and in vitro data

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