The problem of testing horse kidneys for the presence of antibiotics at meat inspection: how to avoid a false positive reaction.

This research investigated the issue of false positives in testing horse kidneys for antibiotics. The study concluded that altering the pH conditions where the testing takes place can eliminate false positive results, which were revealed to be caused by the presence of cadmium.

Research Method

• The study examined 33 horse kidneys for inhibitory substances using the Bacillus subtilis BGA method and the Micrococcus luteus ATCC 9341 method. These tests were performed at a pH level of 8.
• A second round of tests was also performed using the same methods, but this time at a pH level of 6 instead.
• In addition to the antibiotic tests, the researchers also measured the cadmium concentration in these kidneys.

Findings

• When the tests were performed at a pH of 8, 24 samples tested positive for antibiotics while 9 tested negative.
• However, when the tests were performed at a pH of 6, all samples tested negative for antibiotics.
• The authors noted a significant change in the pH of the seeded M. luteus test medium – from 6.6 before incubation to 8.7 after 24 hours of incubation at 30 degrees C.
• The average cadmium concentration in the horse kidneys was found to be significantly high, ranging from 10.40 mg/kg to 355.67 mg/kg wet weight.

Conclusions and Recommendations

• The researchers attributed the positive antibiotic results recorded at pH 8 to the presence of cadmium in the kidney samples.
• They observed that the diffusion of cadmium from the horse kidney samples to the test media was different at pH 6 and pH 8.
• As a result, the study concluded that in order to avoid false positive results due to the presence of cadmium, horse kidney samples should be tested for the presence of antibiotics and chemotherapeutic substances at a substrate pH of 6.