Virulence determinants and antimicrobial resistance of E. coli isolated from bovine clinical mastitis in some selected dairy farms of Bangladesh

Md Abdus Sattar Bag; Md Shahidur Rahman Khan; Md Deluar Hossain Sami; Ferdousi Begum; Md Shafiqul Islam; Md Mizanur Rahman; Md Tanvir Rahman; Jayedul Hassan

doi:10.1016/j.sjbs.2021.06.099

Virulence determinants and antimicrobial resistance of E. coli isolated from bovine clinical mastitis in some selected dairy farms of Bangladesh

Saudi J Biol Sci. 2021 Nov;28(11):6317-6323. doi: 10.1016/j.sjbs.2021.06.099. Epub 2021 Jul 6.

Authors

Md Abdus Sattar Bag¹, Md Shahidur Rahman Khan¹, Md Deluar Hossain Sami¹, Ferdousi Begum², Md Shafiqul Islam¹, Md Mizanur Rahman³, Md Tanvir Rahman¹, Jayedul Hassan¹

Affiliations

¹ Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
² Department of Livestock Services, Ministry of Fisheries & Livestock, Krishi Khamar Sarak, Farmgate, Dhaka 1215, Bangladesh.
³ Border Guard Bangladesh Farm, Head Quarter Battalion, Border Guard Bangladesh, Pilkhana, Dhaka 1205, Bangladesh.

Abstract

E. coli is one of the major significant pathogens causing mastitis, the most complex and costly diseases in the dairy industry worldwide. Present study was undertaken to isolate, detect the virulence factors, phylogroup, antimicrobial susceptibility and antimicrobial resistance genes in E. coli from cows with clinical mastitis. A total of 68 milk samples comprising 53 from clinical mastitis and 15 from apparently healthy cattle were collected from four different established dairy farms in Bangladesh. E. coli was isolated from the milk samples and identified by PCR targeting malB gene and sequencing of 16S rRNA gene. E. coli isolates were screened by PCR for the detection of major virulence genes (stx, eae and cdt) of diarrheagenic E. coli followed by phylogenetic grouping. Antimicrobial susceptibility of the E. coli isolates was determined by disk diffusion test and E. coli showing resistance was further screened for the presence of antimicrobial resistance genes. E. coli was isolated from 35.8% of the mastitis milk samples but none from the apparently healthy cattle milk. All the E. coli isolates were negative for stx, eae and cdt genes and belonged to the phylogenetic groups A and B1 which comprising of commensal E. coli. Antibiotic sensitivity testing revealed 84.2% (16/19) of the isolates as multidrug resistant. Highest resistance was observed against amoxicillin (94.5%) followed by ampicillin (89.5%) and tetracycline (89.5%). E. coli were found resistant against all the classes of antimicrobials used at the farm level. Tetracycline resistance gene (tetA) was detected in 100% of the tetracycline resistant E. coli and blaTEM-1 was present in 38.9% of the E. coli isolates. Findings of this study indicate a potential threat of developing antimicrobial resistance in commensal E. coli and their association with clinical mastitis. Occurrence of multidrug resistant E. coli might be responsible for the failure of antibiotic therapies in clinical mastitis as well as pose potential threat of transmitting and development of antibiotic resistance in human.

Keywords: Antibiotic resistance; Bangladesh; Cattle; Clinical mastitis; Dairy farms; E. coli.