Lori L. Layman

Isolation and Characterization of Methicillin-Resistant Staphylococcus aureus from Pork Farms and Visiting Veterinary Students

In the last decade livestock-associated methicillin-resistant S. aureus (LA-MRSA) has become a public health concern in many parts of the world. Sequence type 398 (ST398) has been the most commonly reported type of LA-MRSA. While many studies have focused on long-term exposure experienced by swine workers, this study focuses on short-term exposures experienced by veterinary students conducting diagnostic investigations. The objectives were to assess the rate of MRSA acquisition and longevity of carriage in students exposed to pork farms and characterize the recovered MRSA isolates. Student nasal swabs were collected immediately before and after farm visits. Pig nasal swabs and environmental sponge samples were also collected. MRSA isolates were identified biochemically and molecularly including spa typing and antimicrobial susceptibility testing. Thirty (30) veterinary students were enrolled and 40 pork farms were visited. MRSA was detected in 30% of the pork farms and in 22% of the students following an exposure to a MRSA-positive pork farm. All students found to be MRSA-positive initially following farm visit were negative for MRSA within 24 hours post visit. Most common spa types recovered were t002 (79%), t034 (16%) and t548 (4%). Spa types found in pork farms closely matched those recovered from students with few exceptions. Resistance levels to antimicrobials varied, but resistance was most commonly seen for spectinomycin, tetracyclines and neomycin. Non-ST398 MRSA isolates were more likely to be resistant to florfenicol and neomycin as well as more likely to be multidrug resistant compared to ST398 MRSA isolates. These findings indicate that MRSA can be recovered from persons visiting contaminated farms. However, the duration of carriage was very brief and most likely represents contamination of nasal passages rather than biological colonization. The most common spa types found in this study were associated with ST5 and expands the range of livestock-associated MRSA types.

Bioavailability and pharmacokinetics of oral meloxicam in llamas.

BackgroundSouth American camelids in the United States have rapidly developed into an important agricultural industry in need of veterinary services. Pain management is challenging in camelids because there are no drugs currently approved by the U.S. Food and Drug Administration for use in these species. Dosage regimens used for many therapeutic drugs have been extrapolated from other ruminants; however, the pharmacokinetics, in camelids, may differ from those of other species. Studies investigating the pharmacokinetics of cyclooxygenase-2 (COX-2) selective non-steroidal anti-inflammatory drugs in camelids are deficient in the published literature. Six adult llamas (121- 168 kg) were administered either a 1 mg/kg dose of oral or a 0.5 mg/kg dose of IV meloxicam in a randomized cross-over design with an 11 day washout period between treatments. Plasma samples collected up to 96 hours post-administration were analyzed by high pressure liquid chromatography and mass spectrometry detection (HPLC-MS) followed by non-compartmental pharmacokinetic analysis.ResultsA mean peak plasma concentration (CMAX) of 1.314 μg/mL (Range: 0.826 – 1.776 μg/mL) was recorded at 21.4 hours (Range: 12.0 – 24.0 hours) with a half-life (T ½ λz) of 22.7 hours (Range: 18.0 – 30.8 hours) after oral meloxicam administration. In comparison, a half-life (T ½ λz) of 17.4 hours (Range: 16.2 – 20.7 hours) was demonstrated with IV meloxicam administration. The oral bioavailability (F) of meloxicam (dose normalized) was 76% (Range: 48 – 92%). No adverse effects associated with either treatment modality were observed in the llamas.ConclusionsThe mean bioavailability (F) of oral meloxicam was 76% indicating a high degree of gastrointestinal absorption. Plasma meloxicam concentrations >0.2 μg/mL were maintained for up to 72 h after oral administration; >0.2 μg/mL is considered to be the concentration of meloxicam required for analgesic effects in other species such as the horse. These data suggest that a single dosage of oral meloxicam at 1 mg/kg could potentially maintain therapeutic concentrations in plasma for up to 3 days in adult llamas.

An Economic Analysis of Feeding Cull Sows1

ABSTRACT The objectives of this study were to estimate the amount of feed and associated costs of adding BW to cull sows. Body weight, backfat, loin eye area, heart and jowl girth, and flank-to-flank measurements were recorded for 29 cull sows approximately every 14 d for a total of 96 d. Feed disappearance and BW gain for each interval was used to calculate performance traits, total revenue, total costs, and net margin. The period of greatest efficiency was from 0 to 14 d, equaling 0.37, 0.41, 0.26, and 0.28 for sows in USDA market weight classes 1 through 4, respectively. Feed efficiency decreased throughout the trial, yet at a slower rate. Average daily feed intake (i.e., feed disappearance), BW gain, and revenue increased (P

Characterization of Lesions in U.S. Cull Sows

Physical and reproductive conditions of 3,158 cull sows from 2 U.S. Midwestern harvest facilities were assessed. Body condition, feet, shoulders, teeth, lungs, and reproductive tracts were visually evaluated for gross lesions at harvest. Based on the observations of this study, body condition score (BCS) was associated with several abnormal conditions of sows. Foot-related lesions (overgrown toes, foot pad lesions) represented the most frequently documented lesions. Temporal associations of the interactions between lesions and BCS are unknown. Even though causal relations were not established by this study, the strong associations observed suggest that sows who do not respond to increased feeding with improved BCS could reasonably be expected to have additional lesions that may impact performance and welfare. On-farm management practices may be related to 1 or more lesions (including foot lesions) that had a high prevalence in this study. Farm management practices and nonhuman animal welfare could not be evaluated with this study so no extrapolation can be given to the type of animal housing or the antemortem behavior of these sows.