Vet World   Vol.16   May-2023  Article-1

Phenotypic diagnosis and genotypic identification of Bacillus cereus causing subclinical mastitis in cows

Background and Aim: Bovine mastitis is a disease that affects dairy cows and impacts the global dairy industry. Bacillus spp. can infect the mammary gland during lactation, intramammary treatment, or dry cow therapy. This study aimed to isolate and identify Bacillus spp. in raw milk samples from cows with subclinical mastitis from dairy farms in Beheira, Giza, Alexandria, and Menoufia Governorate, Egypt. We also investigated their antibiotic sensitivity and detected the enterotoxigenic and antibiotic resistance genes.

Materials and Methods: A total of 262 milk samples (15-20 ml each) were examined microscopically, biochemically, and phenotypically. A polymerase chain reaction was used for genotypic identification and detecting antibiotic-resistance and enterotoxigenic genes. Antibiotic sensitivity was tested using the agar well diffusion test.

Results: Bacillus cereus was identified in 47.7% of samples. Nhe and hblD enterotoxin genes were found in 93.64% (103/110) and 91.82% (101/110) of the samples, respectively. Tetracycline and β-lactam antibiotic-resistance genes were present in 0% (0/110) and 98.18% (108/110), respectively, of the samples. All isolates were resistant to cefepime, cefixime, and oxacillin, while they were susceptible to amoxicillin-clavulanic, chloramphenicol, ampicillin/sulbactam, and levofloxacin.

Conclusion: These results highlight the need to promote awareness regarding B. cereus, the most common pathogen causing mastitis in Egyptian dairy cows. We also emphasized that antibiotic misuse during mastitis is a potential public health threat. Keywords: antibiotics, dairy cows, Egypt, lactation.

Keywords: antibiotics, dairy cows, Egypt, lactation.

How to cite this article: Eid RH, Aref NE, and Ibrahim ES (2023) Phenotypic diagnosis and genotypic identification of

Received: 16-01-2023  Accepted: 14-03-2023     Published online: 07-05-2023

Corresponding author:    E-mail: dr.eman911@yahoo.com

DOI: 10.14202/vetworld.2023.888-894

Copyright: Eid, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.