Frequency of resistance to β-lactam antibiotics and the presence of beta-lactamase producing blaTEM gene in Escherichia coli isolated from the milk of cows with mastitis

Subject Areas : Veterinary Clinical Pathology

Samira Vahabian ¹ , Mehdi Ghiami rad ² , Ahmad Babazadeh Badoustani ³

1 - MSc. Graduate, Department of Cellular and Molecular Biology, Rabe Rashid Institute of Higher Education, Tabriz, Iran.
2 - Assistant Professor, Department of Microbiology, Faculty of Basic Science, Ahar Branch, Islamic Azad University, Ahar, Iran.
3 - Department of Biology, School of Natural Sciences, University of Tabriz, Tabriz, Iran.

Received: 2023-10-25 Accepted : 2024-02-20 Published : 2024-08-20

Keywords: Antibiotic resistance, blaTEM, Bovine mastitis, Escherichia coli, Extended-spectrum β-lactamases.,

Abstract :

Mastitis is the most important economic disease threatening the dairy industry in the world. Escherichia coli are one of the major causes of mastitis, which is treated with antibiotics, especially β-lactams. The emergence and spread of resistance to antibiotics in livestock, as well as the possibility of transferring this resistance to humans, is a serious threat to public health in different communities. The present descriptive-cross-sectional study was conducted to determine the frequency of resistance to beta-lactams in Escherichia coli isolates from cases of bovine mastitis in Tabriz and also evaluate the presence of bla_TEM gene in the isolates. For this purpose, 240 milk samples from cows with clinical mastitis were collected from different regions of Tabriz, Iran. First, the isolates obtained from the samples were identified based on standard microbiology methods, and their antibiotic sensitivity was evaluated by the disc diffusion method. Then, the confirmatory test of beta-lactamase enzyme producers was performed by the combined disc method. Finally, the presence of bla_TEM gene in beta-lactamase-producing isolates was investigated using polymerase chain reaction (PCR). Based on the findings, E. coli was isolated from 50 milk samples of mastitis (20.83% of the samples). Also, in the phenotypic method, 22 isolates (44% of the isolates) were detected as beta-lactamase-producing. The molecular results also showed that only 7 of beta-lactamase-producing isolates in the phenotypic method had the bla_TEM gene. Considering the high frequency of beta-lactamase-producing E. coli in the present study and the possibility of the spread of antibiotic resistance in the livestock population, as well as the possibility of transmission of resistance genes to humans, accurate identification and treatment of animals suffering from mastitis seems necessary.