College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, PR China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, PR China.
Int J Food Microbiol. 2023 Mar 2;388:110098. doi: 10.1016/j.ijfoodmicro.2023.110098. Epub 2023 Jan 20.
Lincomycin is widely used in respiratory and gastrointestinal infection in veterinary medicine and food animal production. Campylobacter members are vital foodborne pathogens causing campylobacteriosis, and the resistance to lincosamides is seldom reported. To date, only the rRNA methyltransferase Erm(B) has been confirmed to be associated with lincosamides resistance in Campylobacter. In this study, we identified a lnu(C) variant conferring lincomycin resistance in this pathogen of chicken origin. The Lnu(C) encoded by this gene variant showed substitution at position 8 (Asn8Lys), 11 (Phe11Leu) and 112 (Leu112Phe), when compared with the firstly reported Lnu(C) from Streptococcus agalactiae. Cloning of the lnu(C) variant into lincosamide-susceptible Campylobacter jejuni NCTC 11168 confirmed its function in conferring resistance to lincomycin with the 32-fold increased MICs. Sequencing analysis showed that the lnu(C) variant was located within a MTnSag1-like transposon together with insLNU, which is inserted between panB and cj0299 genes on the chromosome. lnu(C) gene was distributed among C. coli globally, and various STs were involved in the dissemination of lnu(C). Although transposition mediated by MTnSag1-like transposon failed to occur, the horizontal transfer mediated by natural transformation and reservoir for resistance genes may facilitate their adaptation to the antimicrobial selection pressure in chickens, which should not be ignored.
林可霉素广泛用于兽医和食品动物生产中的呼吸道和胃肠道感染。弯曲菌属成员是重要的食源性病原体，可引起弯曲菌病，而对林可酰胺类的耐药性很少报道。迄今为止，只有 rRNA 甲基转移酶 Erm(B)被证实与弯曲菌中的林可酰胺类耐药性有关。在本研究中，我们鉴定了一种在鸡源弯曲菌中赋予林可霉素耐药性的 lnu(C)变体。与首次从无乳链球菌报道的 Lnu(C)相比，该基因变异体编码的 Lnu(C)在 8 位（Asn8Lys）、11 位（Phe11Leu）和 112 位（Leu112Phe）发生取代。将 lnu(C)变体克隆到林可酰胺敏感的空肠弯曲菌 NCTC 11168 中，证实其在赋予林可霉素耐药性方面的功能，其 MIC 增加了 32 倍。测序分析表明，lnu(C)变体位于与 insLNU 一起的 MTnSag1 样转座子内，该转座子插入染色体上 panB 和 cj0299 基因之间。lnu(C)基因在全球范围内分布于 C. coli 中，并且不同的 ST 参与了 lnu(C)的传播。尽管 MTnSag1 样转座子介导的转座未能发生，但自然转化和耐药基因库介导的水平转移可能有助于它们适应鸡中的抗菌选择压力，这一点不容忽视。
