Vet World Vol.16 July-2023 Article-25
Research Article
Veterinary World, 16(7): 1562-1571
https://doi.org/10.14202/vetworld.2023.1562-1571
Phenotypic and genotypic characterization of erythromycin-resistant Staphylococcus aureus isolated from bovine subclinical mastitis in Egypt
2. Department of Microbiology and Immunology, National Research Centre, Dokki, Egypt.
3. Department of Zoonosis, National Research Centre, Dokki, Egypt.
4. Department of Parasitology and Animal Diseases, National Research Centre, Dokki, Egypt.
5. Department of Animal Medicine, Faculty of Veterinary Medicine, Aswan University, Egypt.
Background and Aim: Subclinical mastitis (SCM) caused by erythromycin-resistant Staphylococcus aureus is a significant disease in lactating animals. Therefore, it is crucial to understand the genetic factors contributing to erythromycin resistance in S. aureus. This study aimed to estimate the prevalence of S. aureus in milk from subclinical mastitic cattle and buffaloes and tank milk samples as identified by probe-based real-time polymerase chain reaction (PCR) and the genotypic assessment of macrolide and erythromycin resistance profiles, as well as to analyze the phylogenetic relatedness of our local isolates of S. aureus.
Materials and Methods: In total, 285 milk samples were analyzed using the California mastitis test to detect SCM. Milk samples were cultured on different specific Staphylococcus media. The presence of S. aureus was confirmed by Gram staining, the catalase and coagulase tests, the detection of hemolytic activity, DNase agar testing, and biofilm activity in Congo red medium. The genotypic identification of S. aureus (nuc) was performed. The determinants of erythromycin (ermA, ermB, ermC, and ermT) and macrolide resistance (msrA) were screened in all isolates. DNA sequencing of our local isolates of S. aureus was used to analyze their phylogenetic relatedness. Moreover, histopathological examination of tissue specimens of mammary gland was performed.
Results: The S. aureus positivity rates were 36.4%, 48.8%, and 63.6% in cattle, buffalo, and bulk tank milk, respectively. Probe-based real-time PCR molecularly confirmed all 62 S. aureus isolates. Thirty-one isolates were subjected to PCR to create profiles of their genotypic erythromycin resistance. ermA, ermB, ermC, and ermT were present in 5 (8%), 26 (41.9%), 18 (29%), and 15 (24.1%) S. aureus isolates, respectively. Moreover, msrA was found in three (4.8%) strains. Eight PCR products were produced using standard PCR for DNA sequencing. Multiple sequence alignment, phylogenetic tree construction, and analysis of nuc in S. aureus revealed a high degree of homology (100%) with S. aureus strains isolated from milk in cases of bovine mastitis in India and Kenya. Histological analysis of udder tissues revealed extensive aggregation of mononuclear inflammatory cells in the interstitial connective tissue, primarily lymphocytes, and macrophages.
Conclusion: This study showed a high prevalence of erythromycin resistance in S. aureus isolates. This information is vital for controlling mastitis and the spread of resistance genes between bacterial strains and hosts. Moreover, the probe-based real-time PCR approach is helpful for the rapid screening of S. aureus isolates and the consequent efficient treatment and control of S. aureus mastitis. Keywords: antimicrobial resistance, bovines, Egypt, erythromycin resistance, genetic diversity, Staphylococcus aureus, subclinical mastitis.
Keywords: antimicrobial resistance, bovines, Egypt, erythromycin resistance, genetic diversity, Staphylococcus aureus, subclinical mastitis.
How to cite this article: Abd El-Razik KA, Arafa AA, Fouad EA, Soror AH, Abdalhamed AM, and Elgioushy M (2023) Phenotypic and genotypic characterization of erythromycin-resistant
Received: 28-03-2023 Accepted: 14-06-2023 Published online: 31-07-2023
Corresponding author: Amany A. Arafa E-mail: dr.amanyahmed@yahoo.com
DOI: 10.14202/vetworld.2023.1562-1571
Copyright: Abd El-Razik, 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.