Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand.
Research Unit in Microbial Food Safety and Antimicrobial Resistance, Chulalongkorn University, Bangkok, 10330, Thailand.
J Antimicrob Chemother. 2024 Aug 1;79(8):1856-1864. doi: 10.1093/jac/dkae172.
To characterize the mobile genetic elements and genetic localization of ileS2 in high-level mupirocin-resistant (Hi-MupR) methicillin-resistant Staphylococcus pseudintermedius (MRSP) and MRSA isolates recovered from canine and feline clinical samples.
The identification of bacterial species and presence of mecA and ileS2 genes in MRSP and MRSA isolates were performed using MALDI-TOF MS and PCR, respectively. Antimicrobial resistance (AMR) phenotypes were determined by broth microdilution assays. The genome characteristics, ileS2-containing elements and staphylococcal cassette chromosome mec (SCCmec) were illustrated using complete circular genomes obtained from hybrid assembly of Illumina short-reads and Oxford Nanopore Technologies long-reads. These were analysed through phylogenetic and bioinformatics approaches.
A total of 18 MRSP clinical isolates and four MRSA clinical isolates exhibited the Hi-MupR phenotype and carried multiple AMR genes, including mecA and ileS2 genes. MRSP ST182-SCCmec V (n = 6) and ST282-ΨSCCmec57395-t10 (n = 4) contained the ileS2 transposable unit associated with IS257 on the chromosome. Three MRSA ST398-SCCmec V-t034/t4652 isolates carried ∼42 kb pSK41-like ileS2 plasmids, whereas similar ileS2 plasmids lacking tra genes were found in MRSP ST282-ΨSCCmec57395-t72/t21 isolates. Furthermore, a new group of ileS2 plasmids, carried by MRSP ST45-ΨSCCmec57395, ST433-ΨSCCmecKW21-t05 and ST2165-SCCmec IV-t06, and by one MRSA ST398-SCCmec V-t034 strain, shared the plasmid backbone with the cfr/fexA-carrying plasmid pM084526_1 in MRSA ST398.
This study provides the first evidence of ileS2 integration into the S. pseudintermedius chromosome, which is a rare occurrence in staphylococcal species, and plasmids played a pivotal role in dissemination of ileS2 in both staphylococcal species.
对来自犬猫临床样本的高水平米诺环素耐药（Hi-MupR）耐甲氧西林金黄色葡萄球菌（MRSP）和耐甲氧西林金黄色葡萄球菌（MRSA）分离株中的移动遗传元件和 ileS2 基因的遗传定位进行特征描述。
使用 MALDI-TOF MS 和 PCR 分别鉴定 MRSP 和 MRSA 分离株的细菌种类和 mecA 和 ileS2 基因的存在。通过肉汤微量稀释法测定抗生素耐药表型。使用 Illumina 短读和 Oxford Nanopore Technologies 长读混合组装获得的完整环状基因组来说明基因组特征、含有 ileS2 的元件和葡萄球菌盒染色体 mec（SCCmec）。通过系统发育和生物信息学方法进行分析。
总共 18 株 MRSP 临床分离株和 4 株 MRSA 临床分离株表现出 Hi-MupR 表型，并携带多种抗生素耐药基因，包括 mecA 和 ileS2 基因。ST182-SCCmec V（n=6）和 ST282-ΨSCCmec57395-t10（n=4）MRSP 含有与染色体上 IS257 相关的 ileS2 可移动单元。3 株 ST398-SCCmec V-t034/t4652 的 MRSA 分离株携带约 42kb 的 pSK41 样 ileS2 质粒，而在 ST282-ΨSCCmec57395-t72/t21 的 MRSP 分离株中发现了类似的缺乏 tra 基因的 ileS2 质粒。此外，一组新的 ileS2 质粒，由 MRSP ST45-ΨSCCmec57395、ST433-ΨSCCmecKW21-t05 和 ST2165-SCCmec IV-t06 以及一株 ST398-SCCmec V-t034 分离株携带，与 MRSA ST398 中的 cfr/fexA 携带质粒 pM084526_1 共享质粒骨架。
本研究首次提供了 ileS2 整合到中间葡萄球菌染色体中的证据，这在葡萄球菌属中很少见，而质粒在两种葡萄球菌中 ileS2 的传播中起关键作用。
