Application of pharmacokinetic/pharmacodynamic concepts to the development of treatment regimens for sporadic canine urinary tract infections: Challenges and paths forward.

Antimicrobial efficacy can be predicted based on infection site exposure to the antimicrobial agent relative to the in vitro susceptibility of the pathogen to that agent. When infections occur in soft tissues (e.g.

Approaches to developing judicious uses of veterinary antibacterial drugs.

Development of new veterinary antibacterials is an important and challenging endeavor. Global recognition of antimicrobial resistance as a threat across human, animal, plant, food, and environmental sectors has increased the level of scrutiny on veterinary antibacterial use. Rigorous scientific evaluation of these products has and continues to be the underpinning of effectiveness evaluations and how hazards are identified, characterized, and ultimately used to make evidence-based and risk-based safety decisions.

Proposed Epidemiological Cutoff Values for Ceftriaxone, Cefepime, and Colistin in Salmonella.

We tested a diverse set of 500 isolates of nontyphoidal Salmonella enterica subsp. enterica from various animal, food, and human clinical sources for susceptibility to antimicrobials currently lacking epidemiological cutoff values (ECOFFs) set by the European Committee on Antimicrobial Susceptibility Testing. A consortium of five different laboratories each tested 100 isolates, using broth microdilution panels containing twofold dilutions of ceftriaxone, cefepime, and colistin to determine the minimum inhibitory concentrations of each drug when tested against the Salmonella isolates.

Antimicrobial Drug Resistance in Fish Pathogens.

Major concerns surround the use of antimicrobial agents in farm-raised fish, including the potential impacts these uses may have on the development of antimicrobial-resistant pathogens in fish and the aquatic environment. Currently, some antimicrobial agents commonly used in aquaculture are only partially effective against select fish pathogens due to the emergence of resistant bacteria. Although reports of ineffectiveness in aquaculture due to resistant pathogens are scarce in the literature, some have reported mass mortalities in larvae caused by resistant to trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, and streptomycin.

Establishing Genotypic Cutoff Values To Measure Antimicrobial Resistance in Salmonella.

Whole-genome sequencing (WGS) has transformed our understanding of antimicrobial resistance, helping us to better identify and track the genetic mechanisms underlying phenotypic resistance. Previous studies have demonstrated high correlations between phenotypic resistance and the presence of known resistance determinants. However, there has never been a large-scale assessment of how well resistance genotypes correspond to specific MICs.

Oxytetracycline pharmacokinetics in rainbow trout during and after an orally administered medicated feed regimen.

The pharmacokinetic-pharmacodynamic predictor of antimicrobial activity for tetracyclines is reported to be the area under the concentration-time curve at steady state (AUC(ss)) divided by the minimal inhibitory concentration of the targeted pathogen. Here, we estimate AUC(ss) values for oxytetracycline (OTC) in serum of rainbow trout Oncorhynchus mykiss by using a destructive sampling study design. Seventy-two rainbow trout were fed OTC-medicated feed at 74.

Determination of cyanuric acid residues in catfish, trout, tilapia, salmon and shrimp by liquid chromatography-tandem mass spectrometry.

In May 2007, investigators discovered that waste material from the pet food manufacturing process contaminated with melamine (MEL) and/or cyanuric acid (CYA) had been added to hog and chicken feeds. At this time, investigators also learned that adulterated wheat gluten had been used in the manufacture of aquaculture feeds. Concern that the contaminated feed had been used in aquaculture and could enter the human food supply prompted the development of a method for the determination of CYA residues in the edible tissues of fish and shrimp.

Evaluation of the renal effects of experimental feeding of melamine and cyanuric acid to fish and pigs.

Objective: To determine whether renal crystals can be experimentally induced in animals fed melamine or the related triazine compound cyanuric acid, separately or in combination, and to compare experimentally induced crystals with those from a cat with triazine-related renal failure.

Animals: 75 fish (21 tilapia, 24 rainbow trout, 15 channel catfish, and 15 Atlantic salmon), 4 pigs, and 1 cat that was euthanatized because of renal failure.

Procedures: Fish and pigs were fed a target dosage of melamine (400 mg/kg), cyanuric acid (400 mg/kg), or melamine and cyanuric acid (400 mg of each compound/kg) daily for 3 days and were euthanatized 1, 3, 6, 10, or 14 days after administration ceased.

Determination and confirmation of melamine residues in catfish, trout, tilapia, salmon, and shrimp by liquid chromatography with tandem mass spectrometry.

Pet and food animal (hogs, chicken, and fish) feeds were recently found to be contaminated with melamine (MEL). A quantitative and confirmatory method is presented to determine MEL residues in edible tissues from fish fed this contaminant. Edible tissues were extracted with acidic acetonitrile, defatted with dichloromethane, and cleaned up using mixed-mode cation exchange solid-phase extraction cartridges.

Determination of oxytetracycline levels in rainbow trout serum on a biphenyl column using high-performance liquid chromatography.

We developed a simple and sensitive high-performance liquid chromatography method on a biphenyl column to determine oxytetracycline (OTC) levels in rainbow trout serum. The assay used deproteination, filtration, and subsequent separation on a reverse-phase biphenyl column, with UV detection at 355 nm. OTC (7.

Epidemiologic cutoff values for antimicrobial agents against Aeromonas salmonicida isolates determined by frequency distributions of minimal inhibitory concentration and diameter of zone of inhibition data.

Objective: To develop epidemiologic cutoff values by use of frequency distributions for susceptibility to 4 antimicrobial agents when tested against a representative population of a major aquaculture pathogen, Aeromonas salmonicida.

Sample Population: 217 typical and atypical A salmonicida isolates obtained from 20 states and 12 countries.

Procedures: Species identification of A salmonicida isolates was confirmed by detection of specific nucleotide sequences by use of a PCR assay.