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The first ojective is to develop a live animal test equivalent to FAST by determining the minimum in hibitory concentration (MIC) of commonly used antimicrobials on Bacillus megaterium, both in vitro with spiked urines and in vivo with urine from animals treated with different antimicrobials. Quantitative validation using High Performance Liquid Chromatography (HPLC) will be included. <P> The second goal is to develop, evaluate and disseminate educational material regarding pre-harvest antimicrobial residue testing. To ensure test availablity potential manufacturers of test supplies will be identified and assistance will be provided during test production start-up.
Determine the minimum inhibitory concentrations (MIC) for 14 different antibiotics commonly used in the field, using the ATCC reference strain 9885 of B. megaterium.
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Quantitative measurement of the in vitro activity will be performed for antimicrobials commonly used in beef and dairy cattle. The following antimicrobial groups will be represented: aminocyclitols (spectinomycin), aminoglycosides (gentamicin, neomycin), beta-lactams (penicillin G, ampicillin, ceftiofur), chloramphenicol derivatives (florfenicol), fluoroquinolones (enrofloxacin), lincosamides (lincomycin), macrolides (tilmicosin, tylosin,), sulfonamides (sulfadimethoxine, sulfamethazine), and tetracyclines (oxytetracycline). </P>
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Validate the modified test with urine samples from animals treated with antibiotics (in vivo testing, field conditions). Cattle with a documented medical history indicating not previous antibiotic therapy will be selected. Six animals will be assigned to each of the 14 antimicrobial treatment groups. Urine will be collected from each animal prior to antibiotic exposure to ensure that the urine alone has no inhibitory properties. </P>
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Each animal will then be treated with the FDA approved dose of the assigned antibiotic. Six hours following treatment, urine will be collected again and subjected to both the live animal test as well as HPLC analysis. Serial collection of urine and concurrent renal biopsies will be performed. The intervals of sampling will be determined for each individual antimicrobial using the FDA published residue depletion information. The last sampling will be performed when the legal withdrawal time is elapsed. </P>
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Urine will be subjected to the live animal test and HPLC analysis. In conjunction with producer industry groups, develop educational materials about pre-harvest antimicrobial residue screening that are suitable for dissemination to national professional organizations and individuals involved in the beef and dairy industry. The educational program can be delivered as part of existing producer quality assurance initiatives. The material will focus on antibiotic residue risk evaluation and categorizing cattle based on their relative risk for containing an antibiotic residue. USDA-FSIS, CDC and FDA data and guidelines will be used to develop the categorizing system. </P>
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Additionally, the use of pre-harvest antibiotic residue testing of targeted high-risk animals will be discussed to provide specific information on the benefits and limitations of pre-harvest residue testing. Detailed information will be included on the use of the newly developed pre-harvest antibiotic screening test developed. </P>
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The evaluation of the materials will target both producer and veterinary focus groups. Ensure adequate commercial availability of the new test. We will identify existing suppliers of the components needed to conduct the new test (spores, plates, control neomycin disks) and provide educational information about the usefulness of the new test once it is appropriately validated.</p>
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Presently there is not a pre-harvest antibiotic residue screening test available to mirror the new antibiotic screening test adopted by the USDA-FSIS 2000. This increases the risk of producers marketing an animal with violative residue. A pre-harvest antibiotic screening test that mirrors the USDA-FSIS FAST test will be developed. Disseminate the information to producers and veterinarians.</P>
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Supplies have been ordered for the first phase of this project. Project began September 15, 2002, therefore itis too early to have progress. </P>