Evaluation of false positive results in microbial inhibitor tests for screening antibiotics in goat milk

Rueda, Tamara Romero

doi:10.4995/thesis/10251/48552

Cited by 1 publication

(1 citation statement)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These components include somatic cells, lactoferrin, lysozyme, microbes and free fatty acids, and they may hamper outcomes of microbial inhibitor tests. 29 Depending on the analytical principle of the screening test, these milk components may have a major impact on the outcome of the test, especially because milk is generally assayed shortly after the clinical outbreak, when the milk may still contain these components in relatively high concentrations. It is not necessary to remind the reader that drug approval process is almost exclusively based on studies carried out in healthy animals.…”

Section: Agreement Between Testsmentioning

confidence: 99%

Assessment of ceftiofur residues in cow milk using commercial screening test kits

Durel

Gallina²,

Pellet

2019

Veterinary Record Open

View full text Add to dashboard Cite

Ceftiofur, a third-generation cephalosporin, is one of the most used antibiotics in dairy industry. Intramuscular injection of 1 mg/kgBW ceftiofur hydrochloride (HCl) generally results in 0 hour withdrawal time for the milk in dairy cows. Nevertheless, farmers and dairy processors occasionally complain about ceftiofur-based products in case of positive result to a commercial rapid screening test for the presence of violative residues of antimicrobials (inhibitors) in the bulk milk tank. Six lactating cows were injected with a 50 mg/ml ceftiofur HCl-based product at the dosage regimen of 1 mg/kg, intramuscularly, once a day, for five consecutive days, as per label. Milk samples were then collected just before the very last injection (T0) and then at 12, 24, 36, 48, 60, 72, 84 and 96 hours after the last injection. Individual milk samples were tested using three commercial screening test kits for inhibitor residues: DelvotestSP NT, SNAP Beta-Lactam ST Plus and ROSA MRL Beta-Lactam Test. Since bulk tank is screened in real operating conditions, samples were also diluted to 1:4, 1:10 and tested again. For the Delvotest SP NT, which lowest detected concentration is close the MRL of the ceftiofur (100 µg/kg), all results were negative. For the ROSA MRL Beta-Lactam Test and the SNAP Beta-Lactam ST Plus, several samples yielded positive and doubtful results at T0 and T12. However, after dilution to 1:10, all results were negative. Consequently, when used as officially instructed, the tested 50 mg/ml ceftiofur HCl-based injectable veterinary products are safe, and milk should be free of violative residues of ceftiofur. With consideration to the low specificity and the low positive predictive value of commercial screening tests, positive reactions of the bulk milk should be interpreted as false positive or another risky usage of β-lactam-based medicines in the farm must be investigated.

show abstract

Section: Agreement Between Testsmentioning

confidence: 99%