Lee Gi Yong, Lee Soo In, Seong Hoon Je, Yang Soo-Jin
Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Republic of Korea.
Korean Medicine Data Division, Korea Institute of Oriental Medicine, Daejeon 1672, Republic of Korea.
Antibiotics (Basel). 2025 Feb 21;14(3):217. doi: 10.3390/antibiotics14030217.
: The occurrence of novel variants of staphylococcal cassette chromosome (SCC) in livestock-associated methicillin-resistant (LA-MRSA) has frequently been reported, posing significant zoonotic concern worldwide. In this study, the occurrence of novel types of SCC IX elements was identified in two clonal complex (CC) 398 LA-MRSA strains derived from a pig farm and a slaughterhouse in Korea. : Whole-genome sequence analysis of the two CC398 MRSA-SCC IX strains, designated KF1A-1172 and JS1E-122, revealed that these strains are most closely related to previously characterized strains of CC398 LA-MRSA carrying SCC V isolated from pig farms in Korea. : Further structural analysis of the SCC IX in KF1A-1172 and JS1E-122 revealed the presence of multiple gene complexes (, and a truncated ), including genes for SCC type IX. In addition, the pseudo-SCC (ΨSCC) elements, genes associated with the type 1 restriction-modification (RM) system, and zinc resistance gene , were identified in the SCC IX. : These findings suggest that the multiple recombination events of elements derived from various SCC types contributed to the emergence of the novel SCC IX variant. The identification of these novel SCC IX types in CC398 LA-MRSA also suggests that epidemiological diversification of SCC IX in CC398 LA-MRSA is an ongoing event, necessitating continued surveillance on the emergence of novel SCC variants. This study is the first to report the complete genome sequences of CC398 MRSA carrying SCC IX in Korea.
家畜源耐甲氧西林金黄色葡萄球菌（LA-MRSA）中葡萄球菌盒式染色体（SCC）新变体的出现屡有报道，引起了全球范围内对人畜共患病的重大关注。在本研究中，在源自韩国一个养猪场和一个屠宰场的两株克隆复合体（CC）398 LA-MRSA菌株中鉴定出新型SCC IX元件。对两株CC398 MRSA-SCC IX菌株（分别命名为KF1A-1172和JS1E-122）进行全基因组序列分析，结果显示这些菌株与之前在韩国养猪场分离出的携带SCC V的CC398 LA-MRSA特征菌株关系最为密切。对KF1A-1172和JS1E-122中的SCC IX进行进一步结构分析，发现存在多个基因复合体（包括 和一个截短的 ），其中包括SCC IX型基因。此外，在SCC IX中还鉴定出假SCC（ΨSCC）元件、与1型限制修饰（RM）系统相关的基因以及锌抗性基因 。这些发现表明，源自各种SCC类型的元件的多次重组事件促成了新型SCC IX变体的出现。在CC398 LA-MRSA中鉴定出这些新型SCC IX类型还表明，CC398 LA-MRSA中SCC IX的流行病学多样化仍在持续，有必要持续监测新型SCC变体的出现。本研究首次报道了韩国携带SCC IX的CC398 MRSA的完整基因组序列。
