Insights into Staphylococcus epidermidis in Farmed Nile Tilapia in Egypt: Molecular Characterization and Antibiotic Resistance

Saleh, Abdelatty; Eissa, Alaa Eldin; A  Ghazy, Mohamed; O.Makled, Sarah; Abdel-Mawgood, Ahmed

doi:10.21608/ejvs.2025.328908.2435

Insights into Staphylococcus epidermidis in Farmed Nile Tilapia in Egypt: Molecular Characterization and Antibiotic Resistance

Articles in Press

Document Type : Original Article

Authors

¹ Biotechnology Program, School of Basic and Applied Sciences, Egypt-Japan University of Science and Technology, Alexandria, Egypt.

² Aquatic Animal Medicine and Management Department, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.

³ Biotechnology Program, Basic and Applied Sciences Institute, Egypt-Japan University of Science and Technology (E-JUST), Alexandria, Egypt.

⁴ Oceanography Department, Faculty of Science, Alexandria University, Alexandria, Egypt.

10.21608/ejvs.2025.328908.2435

Abstract

Staphylococcus epidermidis is one of the causative agents of mass mortality in farmed Nile tilapia (Oreochromis niloticus) in Kafr Elsheikh Governorate, Egypt. Diseased farmed Nile tilapia were collected randomly during the fall of 2023 from farms suffering from mass mortalities. Clinical examination revealed severe lesions in the hepatopancreas and eye of the collected diseased fish. Based on morphological and biochemical analyses, the isolated bacteria were suggested to be Staphylococcus sp. Five of the nine isolates were selected for 16S rRNA sequencing based on their consistent phenotypic characterization criteria. One isolate was found to be Bacillus rugosus based on the 16S rRNA sequencing, which is non-pathogenic and out of the scope of this study. The four remaining isolates were found to be S. epidermidis, which have similarities to other S. epidermidis isolates. All isolated S. epidermidis were resistant to ampicillin, erythromycin, chloramphenicol, streptomycin, and amoxicillin; however, they were moderately susceptible to tetracycline and were sensitive to gentamicin and vancomycin.

Keywords