Beta-lactam Antibiotics Residues in Milk Samples Collected in Northern Tunisia

Abstract Avalidation study designed tomeet the requirements of the AOAC Research Institute and the U.S. Food and Drug Administration (FDA), Center for Veterinary Medicine, was conducted for a receptor-based, immunochromatographic method (BetaStar US) for detection of beta-lactam antibiotic residues in raw, commingled bovine milk. The assay was found to detect amoxicillin, ampicillin, cephapirin, cloxacillin, and penicillin G at levels below the FDA tolerance/safe levels but above the maximum sensitivity thresholds established by the National Conference on Interstate Milk Shipments. Results of the Part I (internal) and Part II (independent laboratory) dose-response studies using spiked samples were in very close agreement for all five drugs tested, with differences between the Part I and Part II 90/95 sensitivity values ranging from 0 to 1 ppb. The test was able to detect all five drugs at the approximate 90/95 sensitivity levels when present as incurred residues in milk collected from cows that had been treated with the specific drug. Asixth drug, ceftiofur, was found to be undetectable at levels of 500 ppb (as total ceftiofur metabolites from incurred residues in milk samples). The selectivity of the assay was 100, because no false-positive results were obtained in tests of >1000 control milk samples. The assay was found to be applicable to the testing of frozen raw milk samples. Results of ruggedness experiments established the operating parameter tolerances for the BetaStar US assay. Results of cross-reactivity testing established that the assay detects certain other beta-lactam drugs (dicloxacillin and ticarcillin), but it does not cross-react with any of 30 drugs belonging to other classes. Abnormally high bacterial or somatic cell counts in rawmilk produced no interference with the ability of the test to detect beta-lactams at tolerance/safe levels.

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Comparison of Rapid Tests Used to Detect Antibiotic Residues in Milk1

Journal of Food Protection ◽

10.4315/0362-028x-53.2.158 ◽

1990 ◽

Vol 53 (2) ◽

pp. 158-164 ◽

Cited By ~ 19

Author(s):

GARY F. SENYK ◽

JOSEPH H. DAVIDSON ◽

JANICE M. BROWN ◽

ERIC R. HALLSTEAD ◽

JOHN W. SHERBON

Keyword(s):

Bacillus Stearothermophilus ◽

Raw Milk ◽

Penicillin G ◽

Beta Lactam ◽

Rapid Methods ◽

Milk Samples ◽

Beta Lactam Antibiotics ◽

Rapid Tests ◽

Combined Data ◽

Disc Assay

Five rapid methods for detection of antibiotics in milk were compared. The Bacillus stearothermophilus var. calidolactis disc assay was also performed on the same samples. The rapid methods were: Angenics Spot Test, Charm II, Delvotest P, Penzyme Farm, and Penzyme Lab III. Ten antibiotics (penicillin G, cephapirin, cloxacillin, ampicillin, streptomycin, chloramphenicol, erythromycin, novobiocin, tetracycline, and gentamicin) were used individually to spike eight raw milk samples at five levels of antibiotic. Antibiotic levels were chosen that would result in zones of <16 mm, 16 mm, and >16 mm on the disc assay. Only the disc assay, Charm II and Delvotest P were compared on non-beta-lactam antibiotics. A small percentage of milks with no antibiotic added tested positive with the Charm II and Penzyme Lab III. On combined data for penicillin G, cephapirin, and cloxacillin, for which all methods were compared, the percent correctly categorized as pass (below actionable) for the <16 mm zone spiked level, reject or caution at the 16 mm zone level, and reject or caution at the >16 mm zone level were: Angenics 79, 83, 100; Charm II 66, 92, 100; Delvotest P 74, 93, 100; Disc Assay 100, 74, 100; Penzyme Farm 93, 61, 92; Penzyme Lab III 81,78, 100 respectively. In most cases, the rapid methods showed greater apparent sensitivity than the disc assay and did not fail to reject milks spiked with antibiotic in excess of the 16 mm zone level.

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Rapid Screening Assay for Beta-Lactam Antibiotics in Milk: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/65.5.1186 ◽

1982 ◽

Vol 65 (5) ◽

pp. 1186-1192 ◽

Cited By ~ 2

Author(s):

Stanley E Charm ◽

Ruey K Chi ◽

◽

H Bryant ◽

M Carson ◽

...

Keyword(s):

Cell Wall ◽

Control Point ◽

Collaborative Study ◽

Rapid Screening ◽

Penicillin G ◽

Beta Lactam ◽

Screening Assay ◽

Milk Samples ◽

Beta Lactam Antibiotics ◽

The Mean

Abstract A 15 min assay for beta-lactam antibiotics has been used by dairies for several years as a screening procedure for testing milk tankers before they unload. The test is based on a competition between 14C-penicillin and beta-lactam antibiotics in the milk samples for sites on a microbial cell wall that specifically binds beta-lactam. In a collaborative study, 11 laboratories correctly distinguished 10 coded zero penicillin G samples and 10 coded 0.01 IU/mL samples. The proposed test is qualitative, positive or negative, and can detect the presence of beta-lactam antibiotics at the 0.01 IU/mL level. The control point for determining positive or negative samples is more than 3 standard deviations from the mean of 0.01 IU/mL. The method has been adopted official first action.

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