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  • Author or Editor: Toru Anzai x
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Abstract

Objective—To develop polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for molecular typing of strains of Streptococcus zooepidemicus and to use the new typing method to analyze a collection of isolates from the respiratory tract of Thoroughbreds.

Sample Population—10 strains of S zooepidemicus, 65 isolates from the respiratory tract of 9 yearlings following long distance transportation, and 89 isolates from tracheal aspirates of 20 foals with pneumonia.

Procedure—Phenotypic variations in the SzP protein were detected by western immunoblot analysis. Using PCR-RFLP analysis, genotypes were obtained with primer sets from the SzP gene, followed by restriction endonuclease digestion of the amplicons.

Results—Unique genotypic patterns were obtained with a primer set designed from both ends of the structural gene and the restriction endonuclease Dde I. Forty-five isolates from the lymphoid tissue within the pharyngeal recess (ie, pharyngeal tonsil) of yearlings included 10 SzP genotypes and SzP phenotypes. Isolates from the trachea of each yearling were of a single genotype that was also present among isolates from the pharyngeal tonsil of the same horses. Isolates from tracheal aspirates of foals belonged to 14 genotypes.

Conclusion and Clinical Relevance—Analysis of the SzP gene by use of PCR-RFLP was effective for molecular typing of strains of S zooepidemicus in the study of respiratory tract disease in horses. Results of PCR-RFLP analysis indicate that a single strain of S zooepidemicus can migrate from the pharyngeal tonsil to the trachea at a high rate in horses undergoing long distance transportation. (Am J Vet Res 2002;63:1298–1301)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the pharmacokinetics and tissue distribution of minocycline in horses.

Animals—5 healthy Thoroughbred mares for the pharmacokinetic experiment and 6 healthy Thoroughbred mares for the tissue distribution experiment.

Procedures—Each mare was given 2.2 mg of minocycline hydrochloride/kg, IV. Blood samples were collected once before minocycline administration (0 hours) and 10 times within 48 hours after administration in the pharmacokinetics study, and 24 tissue samples were obtained at 0.5 and 3 hours in the distribution study.

Results—No adverse effects were observed in any of the mares after minocycline administration. The mean ± SD elimination half-life was 7.70 ± 1.91 hours. The total body clearance was 0.16 ± 0.04 L/h/kg, and the volume of distribution at steady state was 1.53 ± 0.09 L/kg. The percentage of plasma protein binding was 68.1 ± 2.6%. Plasma concentration of free minocycline was 0.12 μg/mL at 12 hours. Minocycline was not detected in brain tissue, CSF or aqueous humor at 0.5 hours; however, it was found in all tissues, except in the aqueous humor, at 3 hours.

Conclusions and Clinical Relevance—Clearance of minocycline in healthy mares was greater than that reported for humans. For effective treatment of infections with common equine pathogens, it will be necessary to administer minocycline at a dosage of 2.2 mg/kg, IV, every 12 hours. This drug could be useful for infections in many tissues, including the CNS. The pharmacokinetic and tissue distribution data should aid in the appropriate use of minocycline in horses. (Am J Vet Res 2010;71:1062–1066)

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in American Journal of Veterinary Research

Abstract

Objective—To determine patterns of methicillin-resistant staphylococci isolated from apparently healthy horses.

Sample Population—44 horses from 8 riding clubs in Japan.

Procedure—Methicillin-resistant staphylococci were isolated from the skin or nares, using a selective medium containing a β-(symboric) lactam antibiotic, ceftizoxime. Clonality of isolates was determined by use of pulsed-field gel electrophoresis. Detection of mecA, mecI, and mecR1 genes was accomplished by use of polymerase chain reactions.

Result—Of the 44 horses, 13 (29.5%) yielded 15 isolates of methicillin-resistant staphylococci. The 15 isolates were identified as 6 species (Staphylococcus epidermidis, S lentus, S saprophyticus, S xylosus, S sciuri, and S haemolyticus). However, methicillin-resistant S aureus was seldom isolated. Each isolate contained the mecA gene and had a high resistance to β- lactam antibiotics. Some isolates also were resistant to other antibiotics such as erythromycin and kanamycin.

Conclusions and Clinical Relevance—Methicillinresistant coagulase-negative staphylococci that were highly resistant to various antibiotics were isolated from apparently healthy horses in Japan. These organisms must be considered a potential threat to horses and veterinarians who care for them. (Am J Vet Res 2000;61:1451–1455)

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in American Journal of Veterinary Research

Abstract

Objective—To develop a method for typing Streptococcus equi on the basis of the DNA sequence of the genes that produce an M-like protein and to compare isolates among the United States, Japan, and other countries.

Sample PopulationS equi strains CF32, Hidaka/95/2, and NCTC9682 as well as 82 other isolates from the United States, Japan, and other countries obtained during 1975 to 2001.

Procedure—DNA sequences of the structural genes ( SeM and SzPSe) that produce M-like proteins were determined for 3 representative strains to find a variable region. Variability in this region of SeM was then determined for the other isolates. Amino acid sequences were deduced and analyzed phylogenetically by use of the neighbor-joining method.

Results—Sequence diversity was detected in the N-terminal region of SeM but not in SzPSe of the 3 representative strains. Base substitutions in the variable region of SeM varied in a nonsynonymous manner, resulting in variation in the amino acid sequence. Eighty-five isolates were categorized as 32 types of SeM on the basis of differences in the deduced amino acid sequences.

Conclusions and Clinical Relevance—This study documented a region in the N-terminal portion of SeM that varies in a nonsynonymous manner. This information should be useful in molecular epidemiologic studies of S equi. (Am J Vet Res 2005; 66:2167–2171)

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in American Journal of Veterinary Research