@article{walker_bourassa_qudsieh_hutson_joardar_livingston_2024, title={Research note: A scald water surfactant combined with an organic acid carcass dip reduces microbial contaminants on broiler carcasses during processing}, volume={103}, ISSN={["1525-3171"]}, DOI={10.1016/j.psj.2024.103847}, abstractNote={Organic acids are applied to poultry carcasses during processing to reduce foodborne pathogens and spoilage microorganisms. Scald water surfactant agents employed to improve feather removal may enhance the efficacy of organic acids during processing. This study investigated the effects of concurrent application of a scald water surfactant and organic acid dip on microbial contamination of carcasses processed in a small-scale production model. Broilers were reared in litter floor pens to 47 d of age and slaughtered using standard practices. Carcasses were scalded in either control or surfactant scald water initially and dipped in either a 2% organic acid blend or water after feather removal to complete a 2×2 factorial arrangement with n=15 carcasses per treatment group. The commercially available scald water additive was a slightly alkaline surfactant solution labelled as a feather removal aid. The organic acid dip consisting of lactic and citric acid was maintained at pH of 2.5. Approximately 10 g of neck skin was collected 1-minute post-dipping and placed in buffered peptone water with an added neutralizing agent, sodium thiosulfate. Serial dilutions were performed to determine general coliform (GC), E. coli (EC), and aerobic plate (APC) counts as CFU per gram of skin sample. A significant 0.61, 0.76, and 1.6 log reduction of GC, EC, and APC, respectively, was attributed to use of the organic acid carcass dip (P ≤ 0.01). There were no significant differences in carcass microbial reduction due to surfactant scald water alone. A 0.69, 0.73 (P ≤ 0.05), and 1.96 log reduction of GC, EC, and APC, respectively, was observed in surfactant-scalded, acid-dipped carcasses compared to water-scalded, water-dipped control groups. These data demonstrated that a surfactant scald water additive and an organic acid carcass dip can have beneficial effects of microbial reduction when employed simultaneously during broiler processing.}, number={7}, journal={POULTRY SCIENCE}, author={Walker, Grayson K. and Bourassa, Dianna V and Qudsieh, Rasha and Hutson, Brittany and Joardar, Dinabandhu and Livingston, Matthew L.}, year={2024}, month={Jul} }
 @article{walker_posner_nelson_watson_2024, title={The Transition from Letter Grading to Modified Pass-Fail Grading at a College of Veterinary Medicine: A Narrative Inquiry of Student Experiences}, volume={1}, ISSN={["1943-7218"]}, DOI={10.3138/jvme-2023-0125}, abstractNote={ Compared with traditional letter grading, pass/fail grading is an assessment approach that can alter the educational environment and enhance student wellbeing without compromising education quality. Little is known about the experiences of students during the transition from traditional grading to pass/fail grading. The onset of the COVID-19 pandemic resulted in an abrupt move to modified pass-fail (MPF) grading at North Carolina State University College of Veterinary Medicine (NCSU-CVM), followed by a decision to permanently adopt MPF grading for the entire core pre-clinical doctor of veterinary medicine (DVM) curriculum. This study employed a narrative inquiry of surveys and interviews to facilitate deep understanding of student perspectives during the transition to MPF grading. Focus was placed on understanding what this transition meant for DVM students in terms of life and learning quality. Our analysis identified seven key themes that captured student experiences, which were generally positive, during this transition: education culture, student perceptions of instructor impact, shift from extrinsic to intrinsic valuation of curricular content, competitiveness for external merit-based opportunities, use of letter grading and MPF in a single semester, student recommendations, and wellbeing. Through exploration of these themes and presentation of concerns identified in students’ stories, this study provides guidance for other programs considering revision of their own assessment frameworks. }, journal={JOURNAL OF VETERINARY MEDICAL EDUCATION}, author={Walker, Grayson K. and Posner, Lysa P. and Nelson, Laura L. and Watson, Jesse S.}, year={2024}, month={Jan} }
 @article{walker_harden_suyemoto_thakur_jacob_borst_2023, title={Draft Genome Sequences of Escherichia coli and Enterococcus faecalis Coisolated from Polymicrobial Extraintestinal Infections of Chickens and Turkeys}, volume={2}, ISSN={["2576-098X"]}, DOI={10.1128/mra.01163-22}, abstractNote={
            Coinfections by avian pathogenic
            Escherichia coli
            (APEC) and
            Enterococcus faecalis
            in poultry with colisepticemia have become increasingly recognized. Here, we report draft genome sequences of 18 APEC and 18
            E. faecalis
            strains coisolated from lesions of diseased poultry.
          }, journal={MICROBIOLOGY RESOURCE ANNOUNCEMENTS}, author={Walker, Grayson K. and Harden, Lyndy and Suyemoto, M. Mitsu and Thakur, Siddhartha and Jacob, Megan and Borst, Luke B.}, year={2023}, month={Feb} }
 @article{walker_harden_suyemoto_thakur_jacob_borst_2023, title={Draft genome sequences of 12 Escherichia coli co-isolated with Enterococcus spp. from dogs with polybacterial bacteriuria at a veterinary hospital}, volume={8}, ISSN={["2576-098X"]}, DOI={10.1128/MRA.00262-23}, abstractNote={ABSTRACT
          
            Escherichia coli
            are frequently co-isolated with
            Enterococcus
            spp. from urine cultures of dogs with urinary tract infections (UTIs). Uropathogenic
            E. coli
            (UPEC) are augmented by
            Enterococcus
            in polymicrobial UTIs. We report the draft genome sequences of 12 UPEC co-isolated with
            Enterococcus
            spp. from canine urinary tract infections.
          }, journal={MICROBIOLOGY RESOURCE ANNOUNCEMENTS}, author={Walker, Grayson K. and Harden, Lyndy and Suyemoto, M. Mitsu and Thakur, Siddhartha and Jacob, Megan and Borst, Luke B.}, year={2023}, month={Aug} }
 @article{walker_yustyniuk_shamoun_jacob_correa_vaden_borst_2022, title={Detection of Escherichia coli and Enterococcus spp. in dogs with polymicrobial urinary tract infections: A 5-year retrospective study}, volume={5}, ISSN={["1939-1676"]}, DOI={10.1111/jvim.16445}, abstractNote={AbstractBackgroundUrinary tract infections (UTI) caused by Escherichia coli and Enterococcus spp., which are frequently coisolated in polymicrobial UTI, cause morbidity among dogs and warrant antimicrobial therapy.ObjectivesTo evaluate clinical features of dogs with polymicrobial E. coli and Enterococcal UTI.AnimalsForty‐four client‐owned dogs with polymicrobial bacteriuria and groups of 100 client‐owned dogs with E. coli and Enterococcal monomicrobial bacteriuria.MethodsRetrospective cohort study of medical records of dogs at a university teaching hospital from 2014 to 2019. Prevalence of recurrent UTI and isolate antimicrobial resistance were determined. Clinical outcomes of dogs with recurrent UTI from groups including cost and hospital visits were compared.ResultsRecurrent UTI was more prevalent (P = .05) in dogs with polymicrobial bacteriuria (57%, 95% confidence interval [95% CI]: 42%‐70%) compared to the Enterococcal monomicrobial group (40%, 95% CI: 31%‐50%). Escherichia coli from polymicrobial bacteriuria were more frequently resistant to doxycycline (P < .01, 43%, 95% CI: 29%‐58%) and gentamicin (P = .03, 17%, 95% CI: 9%‐31%) compared to E. coli from monomicrobial bacteriuria (17% and 5%, 95% CI: 11%‐26% and 2%‐11% for doxycycline and gentamicin, respectively). Dogs with recurrent UTI from the polymicrobial UTI group had significantly (P = .05) more hospital visits (mean = 6 visits, 95% CI: 1.7‐9.8) compared to recurrent monomicrobial UTI dogs (mean = 4 and 3 visits, 95% CI: 1.0 to 4.4 and −0.7 to 7.7 for E. coli and Enterococcal monomicrobial UTI, respectively).Conclusions and Clinical ImportanceEscherichia coli and Enterococcus spp. polymicrobial UTI had more frequent adverse clinical outcomes for dogs.}, journal={JOURNAL OF VETERINARY INTERNAL MEDICINE}, author={Walker, Grayson K. and Yustyniuk, Valeriia and Shamoun, John and Jacob, Megan E. and Correa, Maria and Vaden, Shelly L. and Borst, Luke B.}, year={2022}, month={May} }
 @article{pope_walker_rubio_brake_jendza_fahrenholzy_2022, title={Effects of corn particle size distributions and formic acid on productive and processing performance of broilers}, volume={31}, ISSN={["1537-0437"]}, DOI={10.1016/j.japr.2022.100288}, abstractNote={Formic acid (FA) decreases the pH of feed, which could create a less favorable environment for bacteria and improve the efficacy of digestive enzymes. However, research evaluating the effects of feeding coarse corn (CC) particle size distributions and FA to broilers is sparse. The present study was conducted to determine the effects of feeding varying corn particle size distributions and FA on broiler live performance as well as prevalence of cecal Salmonella spp. upon slaughter. A 3 × 2 factorial arrangement of 3 corn particle size distributions (all 395 µm fine corn [FC], 1,642 µm CC blended at a greater inclusion with fine corn to generate a corn particle size of 850 µm (CC-Hi), or 2,290 µm CC blended at a lesser inclusion when compared to CC-Hi to generate a corn particle size of 850 µm (CC-Lo) and 2 dietary levels (0.0 and 0.4%) of partially buffered FA provided by Amasil NA (ANA) were provided from 11 to 48 d of age (32 birds/pen; 12 replicate pens/treatment). CC-Lo and CC-Hi had the same particle size, but different particle size distributions. Birds fed diets with CC and ANA improved their FCR compared with those fed diets with FC and without ANA at 48 d (P ≤ 0.05). Dietary inclusion of FA increased pectoralis minor yield at 43 d (P ≤ 0.05) but did not affect cecal Salmonella carriage. These data indicated that diets with FA and with a CC particle size distribution can be fed during the whole production period of broilers.}, number={4}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Pope, J. T. and Walker, G. K. and Rubio, A. A. and Brake, J. and Jendza, J. A. and Fahrenholzy, A. C.}, year={2022}, month={Dec} }
 @article{walker_suyemoto_hull_gall_jimenez_chen_thakur_crespo_borst_2021, title={Genomic Characterization of a Nalidixic Acid-Resistant Salmonella Enteritidis Strain Causing Persistent Infections in Broiler Chickens}, volume={8}, ISSN={["2297-1769"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85115006803&partnerID=MN8TOARS}, DOI={10.3389/fvets.2021.725737}, abstractNote={Virulent strains of Salmonella enterica subsp. enterica serovar Enteritidis (SE) harbored by poultry can cause disease in poultry flocks and potentially result in human foodborne illness. Two broiler flocks grown a year apart on the same premises experienced mortality throughout the growing period due to septicemic disease caused by SE. Gross lesions predominantly consisted of polyserositis followed by yolk sacculitis, arthritis, osteomyelitis, and spondylitis. Tissues with lesions were cultured yielding 59 SE isolates. These were genotyped by Rep-PCR followed by whole-genome sequencing (WGS) of 15 isolates which were clonal. The strain, SE_TAU19, was further characterized for antimicrobial susceptibility and virulence in a broiler embryo lethality assay. SE_TAU19 was resistant to nalidixic acid and sulfadimethoxine and was virulent to embryos with 100% mortality of all challenged broiler embryos within 3.5 days. Screening the SE_TAU19 whole-genome sequence revealed seven antimicrobial resistance (AMR) genes, 120 virulence genes, and two IncF plasmid replicons corresponding to a single, serovar-specific pSEV virulence plasmid. The pef, spv, and rck virulence genes localized to the plasmid sequence assembly. We report phenotypic and genomic features of a virulent SE strain from persistently infected broiler flocks and present a workflow for SE characterization from isolate collection to genome assembly and sequence analysis. Further SE surveillance and investigation of SE virulence in broiler chickens is warranted.}, journal={FRONTIERS IN VETERINARY SCIENCE}, author={Walker, Grayson K. K. and Suyemoto, M. Mitsu and Hull, Dawn M. M. and Gall, Sesny and Jimenez, Fernando and Chen, Laura R. R. and Thakur, Siddhartha and Crespo, Rocio and Borst, Luke B. B.}, year={2021}, month={Sep} }
 @article{walker_suyemoto_borst_brake_2020, title={Research Note: Repetitive element–based polymerase chain reaction genotyping improves efficiency of Salmonella surveillance in a model broiler production system}, volume={99}, ISSN={0032-5791}, url={http://dx.doi.org/10.1016/j.psj.2019.12.048}, DOI={10.1016/j.psj.2019.12.048}, abstractNote={The genetic relatedness and antimicrobial susceptibility profiles of Salmonella isolated from poultry and their environment were determined. One broiler breeder flock (BBF1) and 2 broiler flocks (BF1 and BF2) were reared over a 1.75-year period on the same poultry research farm. Hatching eggs were obtained from BBF1 to produce BF1 chicks, while BF2 chicks were progeny of a separate, unsampled broiler breeder flock. BF1 and BF2 were reared in the same housing facilities but 6 mo apart. Salmonella isolates were collected via litter sock sampling (BF1), cecal excision (BF1 and BF2), or cloacal swabs (BBF1). Serotyping identified Salmonella enterica subsp. enterica serovar Altona (SA) in BBF1 and S. enterica subsp. enterica serovar Senftenberg (SS) in BF1 and BF2. Genotypic fingerprinting was achieved with Rep-PCR using the (GTG)5 primer and revealed sequence homology among Senftenberg isolates from BF1 and BF2. For each isolate, the minimum inhibitory concentration was determined for 27 antimicrobial agents using Sensititre plates with formularies specific to antimicrobials used in poultry production or those used to control gram negative pathogens. Isolates from the 3 flocks were resistant to clindamycin, erythromycin, novobiocin, penicillin, and tylosin tartrate and demonstrated intermediate resistance to azithromycin, florfenicol, and spectinomycin. These data demonstrated that serovar Altona and Senftenberg were harbored by poultry, the latter appeared to persist in broiler flocks, and both serotypes shared similar patterns of antimicrobial susceptibility in an integrated research operation. In the case of multiple Salmonella isolates, combining genotypic fingerprinting methods with serotyping of representative isolates would reduce the number of samples required for serotyping and more clearly identify relatedness of isolates. These methods facilitate effective surveillance in poultry production systems, thus allowing for implementation of precise Salmonella control measures.}, number={5}, journal={Poultry Science}, publisher={Elsevier BV}, author={Walker, G.K. and Suyemoto, M.M. and Borst, L.B. and Brake, J.}, year={2020}, month={May}, pages={2684–2689} }
 @article{walker_suyemoto_gall_chen_thakur_borst_2020, title={The role ofEnterococcus faecalisduring co-infection with avian pathogenicEscherichia coliin avian colibacillosis}, volume={49}, ISSN={["1465-3338"]}, url={http://dx.doi.org/10.1080/03079457.2020.1796926}, DOI={10.1080/03079457.2020.1796926}, abstractNote={ABSTRACT Enterococcus spp. (ENT) are frequently co-isolated with avian pathogenic E. coli (APEC) from poultry with colibacillosis, a leading cause of flock mortality. Although largely overlooked, ENT may play an active role in these infections. To assess the frequency of ENT co-isolation in colibacillosis, cultures were collected from birds with gross lesions of omphalitis, polyserositis, and septicaemia over a 3-year period from three turkey flocks and three broiler flocks. In birds diagnosed with colibacillosis based on gross findings and isolation of E. coli, ENT were co-isolated with APEC in 35.7% (n = 41/115) of colibacillosis mortality and 3.7% of total mortality (n = 41/1122). Co-isolated APEC and ENT pairs (n = 41) were further characterized using antimicrobial resistance phenotyping and in vitro co-culture assays. E. faecalis (EF) was the most commonly co-isolated species (68% n = 28/41) and tetracycline resistance was the resistance phenotype most commonly found among APEC (51% n = 21/41) and ENT (93% n = 38/41). Under iron-restricted conditions, EF enhanced APEC growth in a proximity-dependent manner and APEC grown in mixed culture with EF exhibited a significant growth and survival advantage (P ≤ 0.01). In an embryo lethality assay, APEC co-infection with EF resulted in decreased survival of broiler embryos compared to mono-infections (P ≤ 0.05). These data demonstrate that EF augmented APEC survival and growth under iron limiting conditions, possibly translating to the increased virulence of APEC in broiler embryos. Thus, ENT co-infections may be a previously unrecognized contributor to colibacillosis-related mortality. Further investigations into the mechanism of this interaction are warranted. RESEARCH HIGHLIGHTS Enterococcus is frequently co-isolated with avian pathogenic E. coli (APEC). Enterococcus faecalis (EF) enhances survival of APEC in iron restricted conditions. EF co-infection increases APEC virulence in broiler embryos.}, number={6}, journal={AVIAN PATHOLOGY}, publisher={Informa UK Limited}, author={Walker, Grayson K. and Suyemoto, M. Mitsu and Gall, Sesny and Chen, Laura and Thakur, Siddhartha and Borst, Luke B.}, year={2020}, month={Nov}, pages={589–599} }
 @article{walker_jalukar_brake_2018, title={The effect of refined functional carbohydrates from enzymatically hydrolyzed yeast on the transmission of environmental Salmonella Senftenberg among broilers and proliferation in broiler housing}, volume={97}, ISSN={0032-5791}, url={http://dx.doi.org/10.3382/ps/pey083}, DOI={10.3382/ps/pey083}, number={4}, journal={Poultry Science}, publisher={Elsevier BV}, author={Walker, G.K. and Jalukar, S. and Brake, J.}, year={2018}, month={Apr}, pages={1469} }