Laboratory evaluation of the improved tube test detection limits for β-lactam residues in Kenyan milk

Abstract

In Kenya there is currently no screening of antimicrobial drug residues in milk. This study evaluated the improved tube test as a possible screening method using seven representatives of the β-lactam antibiotics. The group comprises antimicrobials most frequently used to treat bacterial infections in dairy cows. Each antimicrobial was tested at five concentrations based on established codex alimentarius maximum residue limits (MRLs). Test parameters studied were practicability and limits of detection (LODs) compared to MRLs and repeatability. The LODs established using a logistic regression model were: penicillin G (2 μg /kg), ampicillin (2 μg /kg), amoxicillin (2 μg /kg), oxacillin (30 μg /kg), cefalexin(100 μg /kg), cephapirin(60 μg /kg) and ceftiofur(100 μg /kg) all within codex alimentarius MRLs. The cost per ten samples using the improved tube test was less than 1 USD compared with 5 USD for the Delvo test. The improved tube test is concluded to be an affordable method, which could be used for qualitative identification of residues in low-income countries dairies.


Key Words: Improved tube test, β-lactams, Kenyan milk, maximum residue limits.


African Journal of Biotechnology Vol.3(1) 2004: 82-87