宁夏地区一株奶牛源耐甲氧西林金黄色葡萄球菌流行株的高通量测序分析

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

摘要:

【背景】耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus, MRSA)是一种常见的条件性致病菌，由MRSA感染导致的奶牛乳腺炎给奶牛养殖户带来了重大的经济损失。【目的】了解宁夏地区奶牛源MRSA流行株基因组序列特征，为MRSA感染的防治提供理论依据。【方法】采用琼脂扩散法对分离株ld11进行抗菌药物敏感性试验，同时运用Illumina高通量测序平台对其基因组DNA进行高通量测序，使用网络数据库对获得的测序序列进行处理分析。【结果】药敏试验结果显示分离株ld11对头孢噻呋、磺胺异恶唑、氨苄西林、红霉素、庆大霉素、苯唑西林、克林霉素、四环素和多西环素耐药，数据分析显示分离株ld11携带耐药基因aadD、spc、str、blaZ、mecA、cat(pC194)、erm(A)、norA、tet(k)和tet(M)，二者之间有很好的相关性；分离株ld11携带的耐药基因多于MRSA参考菌株，且分离株ld11和MRSA252的亲缘关系较近。COG功能分析和GO注释结果显示，与维持菌体基本功能和菌株生长增殖相关的基因占优势；KEGG通路分析结果显示，属于代谢通路的基因占比最多。从该菌株基因组序列上共检测到4个基因岛、9个疑似的CRISPR序列和1个完整的前噬菌体序列。【结论】揭示了宁夏地区奶牛源MRSA流行株的部分基因组序列信息，为MRSA菌株间基因组序列信息的比较分析及MRSA感染的防控提供参考依据。

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.