High-throughput sequencing analysis of a methicillin-resistant Staphylococcus aureus strain in dairy cattle in Ningxia province

Abstract:

[Background] Methicillin-resistant Staphylococcus aureus (MRSA) is a common conditional pathogenic bacterium. Mastitis in dairy cows caused by MRSA infection has brought significant economic losses to dairy farmers. [Objective] To understand the genomic sequence characteristic of MRSA epidemic strain in dairy cows in Ningxia province, and provide a theoretical basis for the prevention and treatment of MRSA infection. [Methods] The isolate ld11 was tested for antimicrobial susceptibility by agar diffusion method, and the high-throughput sequencing of genomic DNA of isolate ld11 was carried out based on Illumina high-throughput sequencing platform, and the obtained sequencing sequences were processed and analyzed through network databases. [Results] The susceptibility test showed that the isolate ld11 was resistant to ceftiofur, sulfisoxazole, ampicillin, erythromycin, gentamicin, oxacillin, clindamycin, tetracycline, and doxycycline, and data analysis showed isolate ld11 carried the drug resistance genes aadD, spc, str, blaZ, mecA, cat(pC194), erm(A), norA, tet(k), and tet(M), and there was a good correlation between the two; The isolate ld11 carried more resistance genes than the MRSA reference strains, and the relationship between isolate ld11 and MRSA252 was closer. The results of COG (Clusters of orthologous groups of proteins) functional analysis and GO (Gene ontology) annotation showed that the genes involved in maintaining the basic functions of the cells and the growth and proliferation of the strains predominated. The KEGG (Kyoto encyclopedia of genes and genomes) pathway analysis showed that the genes belonging to the metabolic pathway accounted for the most; four gene islands, nine questionable CRISPR sequences, and one complete prophage sequence were detected from the genome sequence. [Conclusion] This study revealed partial genomic sequence information of MRSA epidemic strain in dairy cows in Ningxia, which provided a reference for comparative analysis of genomic sequence information and prevention and control of MRSA infection among MRSA strains.