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Abstract

Objectives

To determine tilmicosin concentrations in serum and tissues of rabbits given a single dose of 25 mg of tilmicosin/kg of body weight. To examine the effects of tilmicosin treatment (25 mg/kg, SC) in rabbits with pasteurellosis.

Procedure

After receipt of tilmicosin, healthy New Zealand White female rabbits (n = 3 at each time) were euthanatized at 2, 4, 8, 24, 48, and 72 hours for collection of blood samples and tissue specimens; 4 rabbits served as untreated controls. Rabbits (male and female) with pasteurellosis (n = 42) also were treated. Tilmicosin concentration was determined in serum, lung, and uterine tissues. Rabbits with pasteurellosis were treated with tilmicosin. Response was monitored, using bacteriologic culturing and antibiotic resistance and susceptibility testing, and by scoring clinical signs of disease.

Results

Serum tilmicosin concentration reached 1.91 ±0.18 μg/ml after 2 hours, decreased to 0.77 ± 0.07 μg/ml by 8 hours, and was below minimum inhibitory concentrations for Pasteurella multocida at 24 hours. Terminal half-life in serum was 5.97 hours. Lung and uterus concentrations were 14.43 ± 1.34 and 11.57 ± 0.09 ppm at 2 hours, and were 5.10 ± 1.05 and 8.87 ± 1.66 ppm at 24 hours, respectively. 69% (29/42) of rabbits with pasteurellosis responded favorably in 3 days. Second treatment was required in 31% (13/42), and 5 of these rabbits had clinical signs on day 6; 2 of these 5 had improved. Treatment success rate was 93% (39/42). Of the rabbits that were culture positive on day 0, 35% (6/17) remained positive on day 3. 1 of 6 rabbits was culture positive on day 6.

Conclusion

Tilmicosin (25 mg/kg, SC) was an effective treatment for pasteurellosis in New Zealand White rabbits.

Clinical Relevance

Tilmicosin treatment of pasteurellosis in rabbits is useful in research rabbits and in those destined for meat production. A single dose of antibiotic minimizes stress-associated handling. (Am J Vet Res 1996;57:1180-1184)

Free access
in American Journal of Veterinary Research

SUMMARY

Objectives

To evaluate in vitro susceptibility to topical antifungal medications, as measured by minimum inhibitory concentration (MIC) and 50% inhibitory concentration (IC50%), of fungal isolates from horses with ulcerative keratomycosis in Florida; to compare results with those of other studies to identify differences in susceptibility patterns among fungi isolated from horses in different geographic regions; and to note indications of fungal resistance to drugs tested in other studies.

Sample Population

Corneal fungal cultures from client-owned horses from Florida with ulcerative keratomycosis (n = 22).

Procedure

Fungal cultures were plated on Emmons modified Sabouraud dextrose agar and mycobiotic agar, examined weekly for growth, and kept for a total of 30 days. In vitro MIC and IC50% of fluconazole, itraconazole, ketoconazole, miconazole, and natamycin were measured for each fungal isolate.

Results

Aspergillus (n = 9; 41%), Fusarium (7; 32%), Penicillium (2; 9%), Cylindrocarpon (1; 4%), Scytalidium (1; 4%), and Torulopsis (1; 4%) spp and an unidentified yeast (1; 4%) were isolated. Fungi were most susceptible to antifungal drugs in the following order: natamycin and miconazole equally, itraconazole, and ketoconazole, although no significant difference was found among drugs. Fungi were significantly less susceptible to fluconazole (P < 0.0001) than to the other 4 drugs.

Conclusions

Initial antifungal therapy with topically applied natamycin, miconazole, itraconazole, or ketoconazole is recommended for ulcerative keratomycosis in horses in the subtropical environment of Florida.

Clinical Relevance

Specific antifungal treatment of horses with ulcerative keratomycosis should be based on history, results of ophthalmic examination, cytologic findings, isolation of the pathogenic fungus, and known prevalence of unique ocular fungi in specific geographic areas. In vitro antifungal susceptibility testing may be most beneficial in aiding documentation of pharmacologic susceptibility patterns of fungi in specific geographic regions. (Am J Vet Res 1998; 59:138–142)

Free access
in American Journal of Veterinary Research

concentration MIC 50 Minimum inhibitory concentration of 50% of isolates MIC 90 Minimum inhibitory concentration of 90% of isolates OR Odds ratio a. Cycloserine-cefoxitin-fructose agar, Oxoid, Baskingstoke, Hampshire, England. b. Clostridium

Full access
in American Journal of Veterinary Research

minimum inhibitory concentrations were bimodally distributed. An American Type Culture Collection organism ( E coli ATCC 25922) was used as a quality-control strain. The median (aggregate) score of AMR in each group was defined as follows: the ([ n + 1

Full access
in American Journal of Veterinary Research

MIC Minimum inhibitory concentration NPV Negative predictive value PPV Positive predictive value qPCR Quantitative PCR QRDR Quinolone-resistance determining regions ROC Receiver operating characteristic T m Melting temperature

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in American Journal of Veterinary Research

98.3%). All of the Salmonella spp recovered had a minimum inhibitory concentration to ceftriaxone of ≤ 8 μg/mL, indicating that it was unlikely that they possessed the blaCMY -2 gene. Eighty-six percent (43/50) of the herd owners were

Full access
in American Journal of Veterinary Research

results were obtained by visual estimation of growth inhibition, with minimum inhibitory concentrations set at 100%, 90%, and 50% inhibition. The investigators indicated that this technique was reproducible (although data regarding assay reproducibility

Full access
in American Journal of Veterinary Research