Abstract：
Campylobacter spp., such as Campylobacter jejuni and Campylobacter coli, are important zoonotic Gram-negative pathogens that cause acute intestinal diseases in humans. In this study, a retrospective analysis was conducted on previously collected Campylobacter isolates from antimicrobial resistance surveillance. A total of 29 optrA-positive C. coli strains were identified and subjected to second-generation sequencing. Multilocus sequence typing and single nucleotide polymorphism analyses demonstrated that the 29 optrA-positive isolates were genetically homogeneous. Notably, among the 29 isolated strains, the ΔoptrA variants exhibit a nonsense mutation at position 979 where the base C is substituted by T, leading to the formation of a premature termination codon. The alignment of sequences and genetic environmental characteristics suggested that ΔoptrA located on a chromosomally carried multidrug-resistant genomic island. There are other resistant genes on the multidrug resistance genomic island, such as aph(2\'\')-If, aph(3\')-III, aadE, tet(O), tet(L), cat, erm(A), optrA and blaOXA-61. As a result, the 29 ΔoptrA-positive strains displayed susceptibility to both florfenicol and linezolid. The ΔoptrA gene is linked to the erm(A) gene, resulting in the formation of translocatable unit (TU) that are encompassed by two copies of IS1216 mobile elements. Multiple occurrences of similar TUs have been documented in numerous C. coli and provided evidence for the significance of TUs in facilitating the transfer of drug resistance genes in C. coli.
摘要：
弯曲杆菌属。,如空肠弯曲菌和大肠杆菌弯曲菌，是重要的人畜共患革兰氏阴性病原体，可引起人类急性肠道疾病。在这项研究中,我们对之前从抗菌素耐药性监测中收集的弯曲杆菌分离株进行了回顾性分析.鉴定了总共29个optrA阳性的大肠杆菌菌株并进行第二代测序。多位点序列分型和单核苷酸多态性分析表明，29个optrA阳性分离株具有遗传同质。值得注意的是,在29个分离菌株中，ΔoptrA变体在第979位表现出无义突变，其中碱基C被T取代，导致提前终止密码子的形成。序列和遗传环境特征的比对表明，位于染色体携带的多药耐药基因组岛上的ΔoptrA。多药耐药基因组岛上还有其他耐药基因，如aph(2\'\')-如果，aph(3')-III,aadE,tet(O),tet(L),猫,erm(A),optrA和blaOXA-61。因此,29个ΔoptrA阳性菌株对氟苯尼考和利奈唑胺均具有易感性。ΔoptrA基因与erm（A）基因相连，导致形成由IS1216可移动元件的两个拷贝包围的易位单元(TU)。已在许多大肠杆菌中多次出现相似的TU,并且为TU在促进大肠杆菌中耐药性基因的转移中的重要性提供了证据。
