All 11 clinically significant isolates of Branhamella catarrhalis examined in this study were found to produce beta-lactamase. The enzyme was apparently not plasmid associated since extrachromosomal deoxyribonucleic acid was not detected in any of the strains. The beta-lactamase activity of all strains was significantly depressed by the beta-lactamase inhibitors clavulanic acid and CP 45899. Ba...

Uterine diseases in dairy cows can be classified as puerperal metritis, clinical metritis, clinical endometritis, and subclinical endometritis. These diseases are highly prevalent (affect between 20 and 30% of dairy cows) in high producing dairy cows and have been associated with decreased pregnancy per artificial insemination (AI), extended interval to pregnancy, increased culling, and economi...

Antimicrobials are frequently used for treatment of bovine mastitis and few studies have examined modern treatment strategies on large US dairy farms. The objective of this study was to describe treatment practices for clinical mastitis occurring in cows on large dairy herds in Wisconsin. Treatments performed on 747 cows experiencing cases of mild, moderate, or severe symptoms of clinical masti...

Dairy heifers were treated 0 to 90 d, 90 to 180 d, or 180 to 270 d prepartum with one of five different antibiotic products to determine the best time and with which product they should be treated prior to calving. Two hundred thirty-three heifers were included in the study. At the initial sampling, 56.5% of quarters were infected with some type of organism and 15.4% of quarters were infected w...

Staphylococcus aureus produces four types of beta-lactamase (A, B, C, and D). To investigate the effect of specific beta-lactamase type upon staphylococcal resistance, each beta-lactamase was purified to homogeneity, and the Michaelis constants (Km values) and turnover numbers (kcat values) for various penicillin and cephalosporin substrates were determined. Whereas Km values of the four beta-l...

The objective of this study was to develop a method to quantify antimicrobial drug usage and treatment practices on conventional and organic dairy farms that had been recruited to represent a broad spectrum of potential exposure to antimicrobial drugs. Data on disease prevalence and treatment practices of organic (n = 20) and conventional (n = 20) farms were obtained during a farm visit using a...

A simple, rapid, rugged, sensitive, and specific method for the confirmation and quantitation of 10 beta-lactam antibiotics in fortified and incurred bovine kidney tissue has been developed. The method uses a simple solvent extraction, dispersive solid-phase extraction (dispersive-SPE) cleanup, and liquid chromatography-tandem mass spectrometry (LC/MS/MS) for confirmation and quantitation. Disp...