Screening and Molecular Characterization of Antibiotics Resistance Genes of Staphylococcus Species Isolated from the Nasal Cavity of Goats in Adama, Ethiopia

Abstract

Staphylococci spp. are found everywhere in nature and they occur as a part of the normal microbial flora, asymptomatically colonizing the skin and mucous membranes in the nostrils of humans and animals. The aim of this study was to screen and molecularly characterize the antibiotic resistance of Staphylococcus species isolated from the nasal cavity of goats in Adama city. In this study, 40 samples of mucus were collected from the nasal cavity of goats (NCGs). Screening for possible Staphylococcus species isolate (PSSI) such as coagulase, DNase, growth on Mannitol salt agar (MSA) medium, gram staining, and morphological characterization were performed. Factors affecting S. aureus growth were determined and optimization was performed for PSSI-D8. Antimicrobial activities were determined against S. aureus. Molecular characterizations were performed to identify Staphylococcus species. Data were analyzed using Microsoft Excel, SPSS, and Origin Pro8.5. In this study, 34 isolates of PSSIs were obtained from NGCs. All are morphologically cocci. All PSSIs were positive results for catalase, gram staining, and urease test. Few isolates were found to be coagulase positive. These isolates might be S. aureus. In this study, PSSIs were identified as S. aureus, S. sciuri, S. simulans, and S. xylosus using MALDI-TOF MS analysis. Antibiotic resistance genes such as blaZ, mecA, and thermo-tolerant gene nuc were detected for PSSIs that isolated NCGs using PCR analysis. Based on 16S rRNA analysis, PSSI-D8 was confirmed to be Staphylococcus aureus with 99.47% sequence similarity. It was found that the isolated strains were (100%) susceptible to chloramphenicol and vancomycin antibiotics. The optimum condition for growth and biomass production for Staphylococcus aureus INCG8 was obtained at pH7, temperature (37oC), and 1.28M of NaCl using glucose as the main carbon source. The Staphylococcus species isolated from the nasal cavity of goats are highly resistant to different antibiotics. This designates the need for further studies on mechanisms of antibiotic resistance