Derek Foster specializes in optimizing antibiotic use in livestock, particularly cattle, to maximize drug efficacy while minimizing resistance in pathogenic enteric bacteria.
Using different methods, such as continuous sampling of the gastrointestinal tract and mammary glands via ultrafiltration, Foster focuses on three research areas. First, in collaboration with Mark Papich, he uses pharmacokinetic modeling to examine the impact of dosing regimens and drug formulations on the concentration of active drugs at the site of action including the airways, intestine and mammary gland to improve therapeutic efficacy.
Second, in collaboration with Megan Jacob and Sophia Kathariou, he is assessing the minimum inhibitory concentration of antibiotics to minimize potential negative effects on human health. He is particularly interested in respiratory infections and mastitis, since these diseases are major drivers of antimicrobial use in cattle. Although the target bacteria reside within the respiratory system and mammary glands, drug diffusion and excretion into the intestinal tract can also increase drug resistance in enteric bacteria such as Escherichia, Enterococci and Campylobacter species, many of which represent substantial threats to human health.
Finally, in collaboration with the Food Animal Residue Avoidance Databank (FARAD) and Ronald Baynes, director of FARAD at NC State, Foster is examining the impact of diseases on drug concentrations by comparing samples collected from infected and non-infected animals. He is also comparing different sampling methods to improve the accuracy of drug analysis, treatment decisions and prediction of withdrawal times, which prevents carryover of drugs into food products.
Foster is board-certified in large animal internal medicine, and has a PhD in gastrointestinal physiology. As a member of the Global Health program, his research has implications for livestock health and the safety of animal source foods in the US and abroad.
Global Health Research Fields
- Antimicrobial resistance
- Enteric diseases
- Food safety
- Livestock health
Main Areas of Expertise
- Therapeutic drug use in livestock
- Continuous sampling methods
- Drug-resistant enteric pathogens (cattle)
- Respiratory infections (cattle)
- Mastitis (cattle)
Global Health Research Interests
- Examining the pharmacokinetics and pharmacodynamics of antibiotics in food animals to optimize efficacy while preventing resistance
- Pharmacokinetic modeling of antibiotics in food animals to identify the minimum inhibitory concentration of antibiotics
- Examining the impact of infectious diseases on antibiotic concentrations in livestock
- Food Animal Residue Avoidance Databank (FARAD)
Myzk DA, Bublitz CM, Sylvester HJ, Mullen KAE, Hobgood GD, Baynes RE, Foster DM. Use of an ultrafiltration device in gland cistern for continuous sampling of healthy and mastitic quarters of lactating cattle for pharmacokinetic modeling. J Dairy Sci 2018 Nov; 101(11):10414-10420 (Pubmed)
Sylvester HJ, Griffith EH, Jacob ME, Foster DM. Environmental and management influences on gastrointestinal nematode prevalence on North Carolina goat farms. J Am Vet Med Assoc 2018 Oct; 253(7): 907-17 (Pubmed)
Ferguson KM, Jacob ME, Theriot CM, Callahan BJ, Prange T, Papich MG, Foster DM. Dosing regimen of enrofloxacin impacts intestinal pharmacokinetics and the fecal microbiota in steers. Front Microbiol 2018 Sep; 9: 2190 (Pubmed)
Foster DM, Sylvester HJ, Papich MG. Comparison of direct sampling and bronchoaleolar lavage for determining active drug concentrations in the pulmonary epithelial lining fluid of calves injected with enrofloxacin or tilmicosin. J Vet Pharmacol Therap 2017 Apr; 40(6):e45-e53 (Pubmed)
Foster DM, Martin LG, Papich MG. Comparison of active drug concentrations in the pulmonary epithelial lining fluid and interstitial fluid of calves injected with enrofloxacin, florfenicol, ceftiofur, or tulathromycin. PLoS One 2016 Feb; 11(2):e0149100 (Article)
Foster DM, Jacob ME, Warren CD, Papich MG. Pharmacokinetics of enrofloxacin and ceftiofur in plasma, interstitial fluid, and gastrointestinal tract of calves after subcutaneous injection, and bactericidal impacts on representative enteric bacteria. J Vet Pharmcol Ther 2016 Feb; 39(1):62-71 (Pubmed)
Global Health Memberships
- American College of Veterinary Internal Medicine (including members from the European College of Bovine Health Management)