Determination of Antibiotic Drug Residues in Cow Milk from Nyandarua, Meru, and Kiambu Counties
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Date
2024-06
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Kenyatta University
Abstract
The cases of antimicrobial resistance (AMR) are on the rise globally and will soon be considered a global health emergency. The rise has been associated with the misuse, underuse, or overuse of antibiotics. A report released by the United Nations (UN) Ad hoc Interagency Coordinating Group on Antibiotics Resistance in 2019 revealed that around 700,000 individuals lose their lives each year because of drug-resistant microbial infections. A new UN report warns that if timely action is not taken, this number could skyrocket, reaching 10 million deaths each year by 2050. One of the contributing factors to the growing resistance to antibiotics in humans is veterinary antibiotics residues found in food of animal origin. Antibiotic residues enter the human systems when farmers do not adhere to the drug withdrawal period of the livestock after treatment, feeding livestock with antibiotics contaminated feed and excessive use of antibiotics to promote animal growth. This study was conducted to establish the presence and quantity of antibiotics drug residues in milk from cattle sampled from Nyandarua, Meru and Kiambu counties in Kenya. Milk samples were collected from selected dairy farms. To determine the sample size, 1-sample binomial proportion equation for simple random sampling of 4% desired precision and 95% confidence interval. The milk sample was received at the Kenya Bureau of Standards (KEBS) biochemical laboratories for analysis. They were screened for the presence of sulfonamides, tetracyclines, and beta-lactams using the Charm ROSA TRIO™ test. Quantification of these antibiotics was done using LC-MS/MS chromatographic method. The results showed that tetracyclines were the most prevalent, followed by beta-lactams, and sulfonamides were the least prevalent. Among the beta-lactams, dicloxacillin was the most prevalent at 9.3%, followed by penicillin and cloxacillin at 3.7% each, and nafcillin at 0.9%. Oxacillin was not detected. Among the tetracyclines, demeclocycline and tigecycline were the most prevalent at 10.3% each, followed by oxytetracycline at 9.3%, chlortetracycline at 7.5%, and doxycycline at 3.7%. Sulfaquinoxaline was the only type of sulfonamide antibiotic that was detected at 0.9%. The levels of beta-lactams in milk from Kiambu were 2.89 µg/kg for penicillin, 3.78 µg/kg for oxacillin, and 5.21 µg/kg for nafcillin. The levels in milk from Nyandarua were 11.09 µg/kg for cloxacillin and 17.16 µg/kg for dicloxacillin. The levels of tetracyclines in milk from Nyandarua were 68.77 µg/kg for oxytetracycline, 88.77 µg/kg for chlortetracycline, 106.41 µg/kg for demeclocycline, and 88. µg/kg for tigecycline. Milk from the three counties had significantly high levels of all sulfonamide antibiotics except sulfamerazine, sulfapyridine, and quinoxaline. Sulfamerazine was the only sulfonamide antibiotic that was not found in milk from all the counties. About 3% of the milk in Kiambu and Nyandarua were found to have penicillin levels above the maximum residue limit (MRL), 5% of milk in Meru had cloxacillin levels above MRL, and 10.5% of milk from Meru and Nyandarua had dicloxacillin above the MRL. These findings suggest that there is an urgent need to control the use of antibiotics in animal management in order to curb antimicrobial resistance (AMR).
Description
A Research Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Science (Biotechnology) in the School of Pure and Applied Sciences of Kenyatta University, June 2024