Detection and determination of stability of the antibiotic residues in cow's milk

• Published in: PloS one Vol. 14; no. 10; p. e0223475
• Main Authors: Kurjogi, Mahantesh, Issa Mohammad, Yasser Hussein, Alghamdi, Saad, Abdelrahman, Mostafa, Satapute, Praveen, Jogaiah, Sudisha
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10-10-2019; Public Library of Science (PLoS)
• Subjects: Animals; Anti-Bacterial Agents - analysis; Antibacterial activity; Antibacterial agents; Antibiotic residues; Antibiotics; Antimicrobial agents; Aqueous solutions; Azithromycin; Azithromycin - pharmacology; Bacillus subtilis - drug effects; Beef cattle; Biology and Life Sciences; Biotechnology; Chemistry; Chromatography; Contamination; Cow's milk; Dairy cattle; Food contamination; Food contamination & poisoning; Heat; High performance liquid chromatography; Hydrogen-Ion Concentration; Kinetic equations; Kinetics; Laboratories; Liquid chromatography; Medicine and Health Sciences; Microbial Sensitivity Tests; Microbiology; Milk; Milk - chemistry; Penicillin; pH effects; Reduction; Research and Analysis Methods; Residues; Safety and security measures; Stability; Studies; Temperature; Temperature effects; Tetracycline - pharmacology; Tetracyclines; Veterinary antibiotics; India
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0223475

In the present study, antibiotic residues were detected in milk samples collected from the dairy herds located in Karnataka, India, by microbiological assay. Subsequently, the detected antibiotics were identified as azithromycin and tetracycline, by high-performance liquid chromatography, further both the antibiotics detected in the cow milk samples were found to be at high concentration (9708.7 and 5460 μg kg-1, respectively). We then investigated the effects of temperature and pH on the stabilities of azithromycin and tetracycline to determine the degradation rate constant k using first-order kinetic equation. Results indicated that significant reduction in stability and antibacterial activity of azithromycin solution when subjected to 70 and 100°C for 24 h. While stability of tetracycline was significantly reduced when subjected to 70 and 100°C for 24 h. However no significant reduction in antibacterial activity of tetracycline was observed at respective temperatures when compared with that of control. In addition, the stabilities of azithromycin and tetracycline were found to be decreased in acidic pH 4-5. The results of the present study revealed the high risk of contamination of milk sample with veterinary antibiotics and also demonstrated the effect of temperature and pH on stability of antibiotics. Therefore the study suggest that the qualitative and quantitative screening of milk for the presence of antibiotics need to be strictly performed to ensure safe drinking milk for consumers.