Identification of single-nucleotide variants associated with susceptibility to Salmonella in pigs using a genome-wide association approach.

BACKGROUND: Salmonella enterica serovars are a major cause of foodborne illness and have a substantial impact on global human health. In Canada, Salmonella is commonly found on swine farms and the increasing concern about drug use and antimicrobial resistance associated with Salmonella has promoted research into alternative control methods, including selecting for pig genotypes associated with resistance to Salmonella. The objective of this study was to identify single-nucleotide variants in the pig genome associated with Salmonella susceptibility using a genome-wide association approach. Repeated blood and fecal samples were collected from 809 pigs in 14 groups on farms and tonsils and lymph nodes were collected at slaughter. Sera were analyzed for Salmonella IgG antibodies by ELISA and feces and tissues were cultured for Salmonella. Pig DNA was genotyped using a custom 54 K single-nucleotide variant oligo array and logistic mixed-models used to identify SNVs associated with IgG seropositivity, shedding, and tissue colonization. RESULTS: Variants in/near PTPRJ (p = 0.0000066), ST6GALNAC3 (p = 0.0000099), and DCDC2C (n = 3, p < 0.0000086) were associated with susceptibility to Salmonella, while variants near AKAP12 (n = 3, p < 0.0000358) and in RALGAPA2 (p = 0.0000760) may be associated with susceptibility. CONCLUSIONS: Further study of the variants and genes identified may improve our understanding of neutrophil recruitment, intracellular killing of bacteria, and/or susceptibility to Salmonella and may help future efforts to reduce Salmonella on-farm through genetic approaches.

Antibody Responses to Salmonella in Pigs from Weaning Up to Marketing and Presence of Salmonella at Slaughter.

Salmonella is estimated to be one of the leading causes of enteric illness worldwide. Human salmonellosis is most frequently related to contaminated food products, particularly those of animal origin, such as pork. Pigs are often asymptomatic carriers of Salmonella, highlighting the importance of identifying high-prevalence farms and effective detection methods. The objectives of this study were to investigate Salmonella antibody responses and their association with on-farm shedding and Salmonella isolation at slaughter. Fourteen groups of pigs from eight farrowing sources were followed from birth to slaughter (totaling 796 pigs). Information about farm management was collected through a questionnaire. Blood and fecal samples were collected four times at different stages of production, and palatine tonsils/submandibular lymph nodes were obtained at slaughter. Sera were tested for Salmonella antibodies by enzyme-linked immunosorbent assay, and fecal/tissue samples were cultured for Salmonella. Data were analyzed using a mixed-effect multivariable modeling method with farm, litter, and pig as random effects. Salmonella seropositivity rates were 20.3%, 5.8%, 15.9%, and 37.3% at weaning, at the end of nursery, at end of grower, and at end of finisher, respectively. Salmonella seropositivity and shedding increased with age (p < 0.05), and pigs shedding Salmonella were more likely to test seropositive (p = 0.02). Antibody response and shedding on-farm had no significant association with isolation of Salmonella from tissues harvested at slaughter. The variation in Salmonella seropositivity due to farm was 28.9% of total variation. These findings indicate that on-farm intervention may be a more effective approach to control Salmonella and to reduce the presence of Salmonella at slaughter. Additionally, the observation that some pigs in this study were Salmonella-negative throughout production and at slaughter is promising with regard to food safety, and studies are needed to explore the genotypes of those pigs.

Ergonomic benefit using heads-up display compared to conventional surgical microscope in Japanese ophthalmologists.

PURPOSE: Occupational musculoskeletal disorders are prevalent in ophthalmic surgeons and can impact surgeons' well-being and productivity. Heads-up displays may reduce ergonomic stress compared to conventional microscopes. This cross-sectional, non-interventional study compared ergonomic experience between heads-up display and conventional ocular microscopes. METHODS: The study protocol was approved by the independent ethics committee and nonprofit organization MINS Institutional Review Board. An online questionnaire was distributed to a sample of ophthalmic surgeons in Japan with experience operating with heads-up display. The questionnaire captured surgeon-specific variables, the standardized Nordic Musculoskeletal Questionnaire, and custom questions to compare heads-up display and conventional microscope and understand long-term impacts of musculoskeletal disorders. RESULTS: Analysis was conducted on responses from 67 surgeons with a mean 25 years of practice and 2.7 years using heads-up display. Many surgeons agreed or strongly agreed that heads-up display reduced the severity (40%) and frequency (40%) of pain and discomfort, improved posture (61%), and improved overall comfort (61%). Of respondents who experienced asthenopia (n = 59) or pain/discomfort during operation (n = 61), 54% reported improvement in asthenopia and 72% reported feeling less pain/discomfort since using heads-up display. Overall, 69% reported preference for heads-up display. CONCLUSION: This study provides novel data on musculoskeletal disorders and the long-term impacts of ergonomic strain reported by ophthalmologists building on existing literature demonstrating ergonomic and other advantages of heads-up display. Future studies with objective ergonomic assessment are warranted to validate these findings.

Successful Implementation of Femtosecond Laser-Assisted Cataract Surgery: A Real-World Economic Analysis.

PURPOSE: To calculate the minimum number of Femtosecond laser-assisted cataract surgery (FLACS) procedures required per month to pay off the fixed investment cost over 5 years to achieve break-even. SETTING: A rural ophthalmology practice located in the mid-West United States. DESIGN: An economic analysis, based on real-world, retrospectively collected data over 12 months, from an ambulatory surgical care perspective. METHODS: FLACS was initiated in 2017 with the LenSx® laser (Alcon Vision LLC., Fort Worth, TX). The incremental cost of FLACS, cases needed to break-even, return on investment (ROI), patient education, and marketing efforts were assessed. The financial analysis considered cataract volume, conversion rates, fixed (eg, principal) and variable (eg, supplies) costs, and revenue in the first 12 months. RESULTS: The clinic performed 2717 cataract surgeries in the 12-month period, with 1304 (48%) of patients converting to FLACS. Of FLACS procedures, 613 (47%) selected an advanced-technology intraocular lens (AT-IOL; eg, toric or lifestyle IOL), and the remaining patients selected a monofocal IOL with laser astigmatism correction. FLACS increased AT-IOL use by 113 procedures (23%) compared to volumes in the year prior to FLACS. Overall, FLACS was predicted to be profitable, with only 13 cases required per month to break even in 5 years. If both facility and physician fees are considered revenue, only eight cases per month are required to break-even in 5 years. CONCLUSION: The practice experienced a greater-than-anticipated conversion to FLACS and increased selection of AT-IOLs, well above the break-even volume required, contributing to a rapid return on their investment.

Comparative Assessment of Ergonomic Experience with Heads-Up Display and Conventional Surgical Microscope in the Operating Room.

PURPOSE: Musculoskeletal pain issues are prevalent in ophthalmic surgeons and can impact surgeon well-being and productivity. Heads-up displays (HUD) can improve upon conventional microscopes by reducing ergonomic stress. This study compared ergonomic outcomes between HUD and a conventional optical microscope in the operating room, as reported by ophthalmic surgeons in the US. METHODS: An online questionnaire was distributed to a sample of surgeons who had experience operating with HUD. The questionnaire captured surgeon-specific variables, the validated Nordic Musculoskeletal Questionnaire, and custom questions to compare HUD and conventional microscope. A multivariable model was built to identify variables that were likely to predict improvement in pain-related issues. RESULTS: Analysis was conducted on 64 surgeons (37 posterior-segment, 25 anterior-segment, and two mixed) with a mean 14.9 years of practice and 2.3 years using HUD. Most surgeons agreed or strongly agreed that HUD reduced the severity (64%) and frequency (63%) of pain and discomfort, improved posture (73%), and improved overall comfort (77%). Of respondents who experienced headaches, or pain and discomfort during operation, 12 (44%) reported their headaches improved and 45 (82%) reported feeling less pain and discomfort since they started using HUD. The multivariable model indicated the odds of reporting an improvement in pain since introducing the HUD in the operating room were 5.12-times greater for those who used HUD in >50% of their cases (P=0.029). CONCLUSION: This study indicates that heads-up display may be an important tool for wellness in the operating room as it can benefit ophthalmic surgeons across several ergonomic measures.

Single nucleotide variants in innate immune genes associated with Salmonella shedding and colonization in swine on commercial farms.

Foodborne human salmonellosis is an important food safety concern worldwide. Food-producing animals are one of the major sources of human salmonellosis, and thus control of Salmonella at the farm level could reduce Salmonella spread in the food supply system. Genetic selection of pigs with resistance to Salmonella infection may be one way to control Salmonella on swine farms. The objective of this study was to investigate the association between genetic variants in the porcine innate immune system with on-farm Salmonella shedding and Salmonella colonization tested at slaughter. Fourteen groups of pigs (total 809) were followed from birth to slaughter. Fecal samples collected five times at different stages of production and tissue samples obtained from tonsil and lymph nodes at slaughter were cultured for Salmonella. Genomic DNA was extracted and analyzed for 40 single nucleotide variants and two indels within porcine innate immune genes that were previously associated with Salmonella infection or other infectious diseases. A survey was used to collect information on farm management practices. A multilevel mixed-effects logistic regression modelling method was used to identify SNVs that are associated with Salmonella shedding and/or Salmonella colonization. One single nucleotide variant in the C-type lectin MBL1 and one single nucleotide variant in the cytosolic pattern recognition receptor NOD1 was associated with increased risk of on-farm shedding (p = 0.010) and internal colonization tested at slaughter (p = 0.018), respectively. These findings indicate the potential of these variants for genetic selection programs aimed at controlling Salmonella shedding and colonization in pigs.

Salmonella fecal shedding in pigs from birth to market and its association with the presence of Salmonella in palatine tonsils and submandibular lymph nodes at slaughter.

Salmonella is an important cause of foodborne illnesses in humans. Food-producing animals, including swine, are a major source of Salmonella in food products. This study investigated on farm Salmonella fecal shedding in pigs at different production stages - from weaning to marketing - and its association with the presence of Salmonella in tissues at slaughter. Fourteen groups from 8 commercial farrowing sources (N = 809 pigs) were monitored 5 times from birth to slaughter. Fecal and tissue samples were collected from pigs and cultured for Salmonella. A survey was conducted to collect farm management information. A multi-level mixed-effects logistic regression modelling method was used to analyze Salmonella shedding over time and the association between Salmonella shedding and the presence of Salmonella in tissue samples. Salmonella was recovered from 13% (421/3339) of fecal samples collected from 809 pigs over the course of the study. Overall, 35% (284) of pigs shed Salmonella at least once, while 12% (99) shed more than once. Salmonella shedding increased as pigs aged (P = 0.01) and increased in the summer months (P < 0.01). Salmonella was isolated from tissue samples collected from 23% (134/580) of pigs; however, the presence of Salmonella at slaughter was not associated with on farm shedding. The seasonal trend in Salmonella shedding and its association with age may be used to identify high-risk groups and implement more effective control measures accordingly. The identification of repeat shedders warrants interventions that target this source of infection on swine farms.

Salmonella est une cause importante de maladies d'origine alimentaire chez les humains. Les animaux de rente, incluant le porc, sont une source majeure de Salmonella dans les produits alimentaires. Au cours de la présente étude nous avons examiné l'excrétion fécale de Salmonella à la ferme à différents stades de la production ­ du sevrage jusqu'à la mise en marché ­ et sont association avec la présence de Salmonella dans les tissus au moment de l'abattage. Quatorze groupes provenant de huit sources commerciales de mise-bas (N = 809 porcs) ont été surveillés cinq fois entre la naissance et l'abattage. Des échantillons de fèces et de tissus ont été prélevés des porcs et cultivés pour Salmonella. Un sondage a été mené pour amasser des informations sur la gestion de la ferme. Une méthode de modélisation de régression logistique à effets mixtes de niveaux multiples a été utilisée pour analyser l'excrétion de Salmonella dans le temps et l'association entre l'excrétion de Salmonella et la présence de Salmonella dans les échantillons de tissus. Salmonella a été isolé de 13 % (421/3339) des échantillons de fèces prélevés des 809 porcs durant la durée de cette étude. Au total, 35 % (284) des porcs ont excrété Salmonella au moins une fois, alors que 12 % (99) ont excrété plus d'une fois. L'excrétion de Salmonella augmentait à mesure que les porcs vieillissaient (P = 0,01) et augmentait durant les mois d'été (P < 0,01). Salmonella a été isolé d'échantillons de tissu prélevés de 23 % (134/580) des porcs; toutefois, la présence de Salmonella au moment de l'abattage n'était pas associée avec l'excrétion à la ferme. La tendance saisonnière dans l'excrétion de Salmonella et son association avec l'âge pourraient être utilisées afin d'identifier les groupes à risque élevé et mettre en place selon le cas des méthodes de maitrise plus efficaces. L'identification d'excréteurs à répétition justifie des interventions qui ciblent cette source d'infection sur les fermes porcines.(Traduit par Docteur Serge Messier).