@article{mzyk_halleran_sylvester_giles_jacob_baynes_foster_2024, title={Continuous sampling of healthy and mastitic quarters of lactating cattle by ultrafiltration after intramammary ceftiofur hydrochloride administration}, volume={8}, ISSN={["1939-1676"]}, url={https://doi.org/10.1111/jvim.17155}, DOI={10.1111/jvim.17155}, abstractNote={Abstract Background Pharmacological activity of intramammary drugs depends on adequate drug concentrations within the cistern, but sampling is often limited. Insight into the active drug concentration within the mammary cistern may assist in determining effective and appropriate therapeutic decisions for cows being treated for mastitis. Objective Evaluate the disposition of ceftiofur hydrochloride administered intramammary in diseased and nondiseased quarters. Whole milk and ultrafiltrate sampling techniques were compared. Animals Ten mature, late lactation Holstein (n = 9) and Jersey (n = 1) dairy cows (422‐670 kg) with naturally occurring clinical mastitis, producing between 1.4 and 15.9 kg/day of milk. Methods Ultrafiltration probes were placed in both mastitic and healthy quarters. Each quarter was treated with 2 doses of 125 mg ceftiofur hydrochloride suspension, and whole milk and milk ultrafiltrate samples were collected. Ceftiofur concentrations in composite whole milk and milk ultrafiltrate were analyzed. Results The maximum concentration of ceftiofur was higher in ultrafiltrate samples, but no differences were identified in healthy or mastitic quarters. The use of ultrafiltration probes provides a novel technique for free drug concentrations within the mastitic and healthy bovine mammary gland. Conclusions and Clinical Importance Significant inter‐ and intracow variability and lower daily milk weights may overestimate ceftiofur concentrations available within the cistern. The pharmacokinetic (PK) parameters reported in milk ultrafiltrate will help establish a link between the PK and the corresponding drug effect, potentially providing a meaningful rationale for the selection of a safe and effective dose in cows with mastitis.}, journal={JOURNAL OF VETERINARY INTERNAL MEDICINE}, author={Mzyk, Danielle A. and Halleran, Jennifer L. and Sylvester, Hannah J. and Giles, Claire B. and Jacob, Megan E. and Baynes, Ronald E. and Foster, Derek M.}, year={2024}, month={Aug} }
 @article{halleran_sylvester_jacob_callahan_baynes_foster_2024, title={Impact of florfenicol dosing regimen on the phenotypic and genotypic resistance of enteric bacteria in steers}, volume={14}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-024-55591-8}, abstractNote={AbstractThe food animal sector’s use of antimicrobials is heavily critiqued for its role in allowing resistance to develop against critically important antimicrobials in human health. The WHO recommends using lower tier antimicrobials such as florfenicol for disease treatment. The primary objective of this study was to assess the differences in resistance profiles of enteric microbes following administration of florfenicol to steers using both FDA-approved dosing regimens and two different detection methods. Our hypothesis was that we would identify an increased prevalence of resistance in the steers administered the repeated, lower dose of florfenicol; additionally, we hypothesized resistance profiles would be similar between both detection methods. Twelve steers were administered either two intramuscular (20 mg/kg q 48 h; n = 6) or a single subcutaneous dose (40 mg/kg, n = 6). Fecal samples were collected for 38 days, and E. coli and Enterococcus were isolated and tested for resistance. Fecal samples were submitted for metagenomic sequencing analysis. Metagenomics revealed genes conferring resistance to aminoglycosides as the most abundant drug class. Most multidrug resistance genes contained phenicols. The genotypic and phenotypic patterns of resistance were not similar between drug classes. Observed increases in resistant isolates and relative abundance of resistance genes peaked after drug administration and returned to baseline by the end of the sampling period. The use of a “lower tier” antimicrobial, such as florfenicol, may cause an increased amount of resistance to critically important antimicrobials for a brief period, but these changes largely resolve by the end of the drug withdrawal period.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Halleran, Jennifer and Sylvester, Hannah and Jacob, Megan and Callahan, Benjamin and Baynes, Ronald and Foster, Derek}, year={2024}, month={Feb} }
 @article{halleran_callahan_jacob_sylvester_prange_papich_foster_2021, title={Effects of danofloxacin dosing regimen on gastrointestinal pharmacokinetics and fecal microbiome in steers}, volume={11}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-021-90647-z}, abstractNote={AbstractFluoroquinolones are a class of antimicrobial commonly used in human medicine, and deemed critical by the World Health Organization. Nonetheless, two formulations are approved for the treatment of respiratory disease in beef cattle. The objective of this study was to determine the gastrointestinal pharmacokinetics and impact on enteric bacteria of cattle when receiving one of the two dosing regimens (high: 40 mg/kg SC once or low: 20 mg/kg IM q48hr) of danofloxacin, a commonly utilized synthetic fluoroquinolone in veterinary medicine. Danofloxacin was administered to 12 steers (age 7 months) fitted with intestinal ultrafiltration devices at two different dosing regimens to assess the gastrointestinal pharmacokinetics, the shifts in the gastrointestinal microbiome and the development of resistant bacterial isolates. Our results demonstrated high intestinal penetration of danofloxacin for both dosing groups, as well as, significant differences in MIC values for E. coli and Enterococcus between dosing groups at selected time points over a 38 day period. Danofloxacin treatment consistently resulted in the Euryarchaeota phyla decreasing over time, specifically due to a decrease in Methanobrevibacter. Although microbiome differences were minor between dosing groups, the low dose group had a higher number of isolates with MIC values high enough to cause clinically relevant resistance. This information would help guide veterinarians as to appropriate dosing schemes to minimize the spread of antimicrobial resistance.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Halleran, J. L. and Callahan, B. J. and Jacob, M. E. and Sylvester, H. J. and Prange, T. and Papich, M. G. and Foster, D. M.}, year={2021}, month={May} }
 @article{mzyk_bublitz_sylvester_mullen_hobgood_baynes_foster_2018, title={Short communication: Use of an ultrafiltration device in gland cistern for continuous sampling of healthy and mastitic quarters of lactating cattle for pharmacokinetic modeling.}, volume={101}, url={https://doi.org/10.3168/jds.2018-14849}, DOI={10.3168/jds.2018-14849}, abstractNote={Pharmacokinetic studies of the drugs in the milk are often limited due to infrequent sampling associated with milking. Alternatively, frequent sample collection with repeated milking may increase drug elimination. The objective of this study was to determine the feasibility of continuously sampling the udder using ultrafiltration. An ultrafiltration probe was placed into the gland cisterns through mammary parenchyma of normal and mastitic quarters of 6 mature mid-lactation Jersey cows with naturally occurring subclinical mastitis. An ultrafiltration probe was secured to the caudal or lateral aspect of the udder depending on the quarter being sampled. The timed interval samples were collected at 0, 2, 4, 6, 8, 12, 18, 24, 28, 32, 36, 48, 60, 72, 84, and 96 h after drug administration. Plasma samples were collected at the same time points. Each cow received 2.2 mg/kg of flunixin intravenously before milking at time 0. All cows were routinely milked by machine every 12 h. Flunixin concentrations in plasma, whole milk, and milk ultrafiltrates were analyzed by use of ultra-high-performance liquid chromatography with mass spectrometric detection. We found no significant effects on the appearance of the milk or the ability to milk the cows after implantation of the ultrafiltration probes. The concentration of flunixin collected from the ultrafiltration probes in the mastitic quarters tended to be greater than that of the healthy quarters. We concluded that collection of ultrafiltration samples from the mammary gland of cows provides a viable means to continuously assess drug concentrations in the milk while continuing to milk the cow normally. This study demonstrates the utility of continuous sampling of milk via ultrafiltration for future pharmacokinetic studies in cattle.}, number={11}, journal={Journal of dairy science}, author={Mzyk, D. A. and Bublitz, C. M. and Sylvester, H. and Mullen, K. A. E. and Hobgood, G. D. and Baynes, R. E. and Foster, Derek}, year={2018}, month={Sep}, pages={10414–10420} }
 @article{swift_foster_rogers_sylvester_griffith_jacob_2017, title={Efficacy of an Escherichia coli O157:H7 SRP Vaccine in Orally Challenged Goats and Strain Persistence Over Time}, volume={14}, ISSN={["1556-7125"]}, url={https://doi.org/10.1089/fpd.2016.2213}, DOI={10.1089/fpd.2016.2213}, abstractNote={Small ruminants have been implicated in outbreaks of Escherichia coli O157:H7 at livestock exhibitions throughout the United States. Additionally, goat meat or milk may serve as a reservoir for foodborne transmission of the organism. These associations highlight the public health importance of an effective strategy to reduce E. coli O157:H7 shedding in goats. We examined the efficacy of the SRP® vaccine in goats orally challenged with E. coli O157:H7. Mixed-breed goats (n = 14) were randomly allocated into vaccinated and unvaccinated treatments (n = 7 per treatment). Goats were housed with a vaccinated and unvaccinated animal in each pen. Feces were collected for 3 weeks, then at necropsy, gastrointestinal contents were collected to determine the concentration of E. coli O157:H7. Three isolates per positive sample were saved and evaluated by pulsed-field gel electrophoresis (PFGE) to assess strain persistence over time. The mean concentration of E. coli O157:H7 in the feces of goats was numerically reduced in the vaccinated treatment; however, it was not statistically significant. In addition, the total number of days goats were fecal positive for E. coli O157:H7 were not different between vaccinated and unvaccinated treatments. Pulsotypes of isolates revealed that goats initially shed two of the four challenge strains of E. coli O157:H7, after which there was a distinct shift to two different strains. Further work is needed to evaluate cost-effective intervention strategies that reliably reduce E. coli O157:H7 shedding in goats, particularly those that may reduce the risk of transmission at public events, including petting zoos and fairs.}, number={3}, journal={FOODBORNE PATHOGENS AND DISEASE}, author={Swift, Jacob M. and Foster, Derek M. and Rogers, Anna T. and Sylvester, Hannah J. and Griffith, Emily H. and Jacob, Megan E.}, year={2017}, month={Mar}, pages={160–166} }
 @article{halleran_sylvester_foster_2017, title={Short communication: Apparent efficiency of colostral immunoglobulin G absorption in Holstein heifers}, volume={100}, ISSN={["1525-3198"]}, url={https://doi.org/10.3168/jds.2016-11904}, DOI={10.3168/jds.2016-11904}, abstractNote={Adequate absorption of bovine colostrum correlates with improved neonatal health. The apparent efficiency of absorption (AEA) of immunoglobulins can be measured using a mathematical equation based on serum and colostral IgG concentration levels, as well as calf body weight and the volume of colostrum being fed. Although commonly measured in research projects, little information is available on the normal AEA across a large group of healthy calves on multiple farms. The purpose of this study was to observe how contributing factors (volume of feeding, birth weight, and time of feeding) can alter AEA and establish a reference range for AEA in healthy calves. Study subjects were 100 Holstein heifer calves from 5 different dairies in North Carolina and Colorado. After a normal calving, the heifer received either 4 or 5.6 L of colostrum within 4 h of birth, an aliquot of the fed colostrum was saved, and a blood sample was collected between 24 and 36 h after birth. Birth weights were measured using the same weight tape on each farm. Radial immunodiffusion assay was performed to obtain IgG concentrations in the colostrum and serum samples. From this data, the AEA was calculated. The AEA ranged from 7.7 to 59.9% with mean of 28.1 ± 9.5% and median of 27.5%. The AEA of 69% of the calves fell between 21 and 40%. The AEA varied widely between calves, even when feeding was standardized. Results suggest that serum IgG concentration may potentially be increased by feeding increased volumes of colostrum or genetic selection, given the wide range of AEA values obtained.}, number={4}, journal={JOURNAL OF DAIRY SCIENCE}, author={Halleran, Jennifer and Sylvester, Hannah J. and Foster, Derek M.}, year={2017}, month={Apr}, pages={3282–3286} }
 @article{foster_poulsen_sylvester_jacob_casulli_farkas_2016, title={Effect of high-pressure processing of bovine colostrum on immunoglobulin G concentration, pathogens, viscosity, and transfer of passive immunity to calves}, volume={99}, ISSN={["1525-3198"]}, url={https://doi.org/10.3168/jds.2016-11204}, DOI={10.3168/jds.2016-11204}, abstractNote={This study aimed to determine the effects of high-pressure processing on the immunoglobulin concentration, microbial load, viscosity, and transfer of passive immunity to calves when applied to bovine colostrum as an alternative to thermal pasteurization. A pilot study using Staphylococcus aureus was conducted to determine which pressure-time treatments are most appropriate for use with bovine colostrum, with the goals of maximizing bacterial inactivation while minimizing IgG content and viscosity changes. Following the pilot study, an inoculation study was conducted in which first-milking colostrum samples from Holstein-Friesian cows were inoculated with known concentrations of various bacteria or viruses and pressure processed at either 300 MPa for up to 60min or at 400MPa for up to 30min. The recovery of total native aerobic bacteria, Escherichia coli, Salmonella enterica ssp. enterica serovar Dublin, Mycobacterium avium ssp. paratuberculosis, bovine herpesvirus type 1, and feline calicivirus were determined after processing. Colostrum IgG content was measured before and after pressure processing. Shear stress and viscosity for each treatment was determined over shear rates encompassing those found during calf feeding and at normal bovine body temperature (37.8°C). Following a calf trial, serum IgG concentration was measured in 14 calves fed 4 L of colostrum pressure processed at 400MPa for 15min. In the pilot study, S. aureus was effectively reduced with pressure treatment at 300 and 400MPa (0, 5, 10, 15, 30, and 45min), with 2 treatments at 400MPa (30, 45min) determined to be inappropriate for use with bovine colostrum due to viscosity and IgG changes. High-pressure processing at 300MPa (30, 45, and 60min) and 400MPa (10, 15, and 20min) was shown to effectively reduce total native aerobic bacteria, E. coli, Salmonella Dublin, bovine herpesvirus type 1, and feline calicivirus populations in bovine colostrum, but no decrease occurred in Mycobacterium avium ssp. paratuberculosis. All inoculation study pressure treatments insignificantly decreased IgG content of colostrum. Treatment of colostrum at 400MPa for 15min during the calf trial decreased IgG content of colostrum. Treatment at 400MPa for 15min increased colostrum viscosity, with 2 of 14 samples requiring dilution with water for calf feeding. Calves fed pressure-processed colostrum had similar serum IgG but lower efficiency of absorption than calves fed heat-treated colostrum. The results of this study suggest that high-pressure processing of bovine colostrum maintains an acceptable IgG level while decreasing bacterial and viral counts. Changes in viscosity sometimes made calf feeding more difficult, but still feasible. Additional research to optimize this technology for on-farm use is necessary.}, number={11}, journal={JOURNAL OF DAIRY SCIENCE}, author={Foster, Derek M. and Poulsen, Keith P. and Sylvester, Hannah J. and Jacob, Megan E. and Casulli, Kaitlyn E. and Farkas, Brian E.}, year={2016}, month={Nov}, pages={8575–8588} }
 @article{schweizer_foster_knox_sylvester_anderson_2016, title={Single vs. double dose of copper oxide wire particles (COWP) for treatment of anthelmintic resistant Haemonchus contortus in weanling lambs}, volume={229}, ISSN={["1873-2550"]}, url={https://doi.org/10.1016/j.vetpar.2016.09.011}, DOI={10.1016/j.vetpar.2016.09.011}, abstractNote={Haemonchus contortus parasitism is a major disease of sheep, with these parasites frequently demonstrating multi-drug class anthelmintic resistance. Copper oxide wire particles (COWP) have shown potential as adjuncts or alternatives to anthelmintics in resistant flocks. The purpose of this study was to compare the efficacy of two different COWP treatment regimens or placebo in the control of H. contortus in weaned lambs within a flock historically shown to have multi-drug resistant H. contortus using the DrenchRite® assay. Data from 43 lambs within 3 treatment groups in a double blind study were included in the experiment. Treatments were administered as a total of 2 boluses, each given on separate occasions (day 0 and day 42), so that each lamb received either 2 placebos, a single dose of 2g COWP followed by placebo, or two doses of 1g COWP. Strongyle-type fecal egg counts (FEC) were performed at initial treatment (day 0), on day 10, at second treatment (day 42), on day 52, and at study end (day 84). At the start of the trial, mean±standard deviation FEC were 1634.4±825.2, 2241.7±1496.8, and 2013.3±1194.2epg for the 2g, 1g×2, and control groups, respectively. At the end of the trial, FEC were 757.1±825.3, 483.4±557.2, and 1660.0±1345.3epg for the 2g, 1g×2, and control groups, respectively. Lambs given a 2g single dose of COWP or a 1g dose of COWP twice had reductions in strongyle-type FEC (p≤0.01) from trial start to trial end, whereas lambs given placebo did not. Average daily gains did not differ significantly among groups. Although copper is potentially toxic to sheep, no signs of toxicity were observed during this trial, which was consistent with similar studies at this treatment dose. The study indicated that administering COWP to lambs at weaning reduced FEC.}, journal={VETERINARY PARASITOLOGY}, author={Schweizer, Nikki M. and Foster, Derek M. and Knox, William B. and Sylvester, Hannah J. and Anderson, Kevin L.}, year={2016}, month={Oct}, pages={68–72} }