College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, People's Republic of China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, People's Republic of China.
Antimicrob Agents Chemother. 2020 Dec 16;65(1). doi: 10.1128/AAC.01622-20.
Tetracyclines are widely used in veterinary medicine and food animal production. members are major foodborne pathogens, and their resistance to tetracycline has been widely reported in different countries. To date, Tet(O), a ribosomal protection protein, is the only confirmed Tet resistance determinant in spp. Here, we reported the detection and characterization of a novel Tet resistance element in spp. of chicken origin. This gene is identified to be a variant of (L), which encodes an efflux pump for Tet resistance. The variant was detected in 14 of the 82 tetracycline-resistant isolates collected from chickens in Henan, China. Cloning of the (L) variant into tetracycline-susceptible NCTC 11168 confirmed its function in conferring resistance to tetracycline and doxycycline. In addition, this (L) variant elevated the MIC (4-fold increase) of tigecycline in the heterologous host. Sequencing analysis indicated the (L) variant was located within a multidrug-resistance genomic island (MDRGI) containing (L) variant IS-ORF1--Δ-IS(O)- This MDRGI is inserted into conserved gene on the chromosome. Multilocus sequence type (MLST) analysis revealed that both clonal expansion and horizontal transfer were involved in the dissemination of the (L) variant. These findings reveal the emergence of a new Tet resistance determinant in spp., which may facilitate their adaptation to the antimicrobial selection pressure in chickens.
四环素类广泛应用于兽医和食用动物生产。 是主要的食源性病原体，其对四环素的耐药性已在不同国家广泛报道。迄今为止，Tet(O)，一种核糖体保护蛋白，是 种中唯一确认的四环素耐药决定因素。在这里，我们报道了一种新型四环素耐药元件在鸡源 种中的检测和特征。该基因被鉴定为 (L) 的变体，它编码一种用于四环素耐药的外排泵。该变体在从中国河南采集的 82 株耐四环素 分离株中检测到 14 株。将 (L) 变体克隆到四环素敏感的 NCTC 11168 中，证实了其对四环素和强力霉素的耐药性。此外，该 (L) 变体使异源 宿主对替加环素的 MIC（增加 4 倍）升高。测序分析表明，(L)变体位于包含 (L)变体 IS-ORF1--Δ-IS(O)-的多药耐药基因组岛 (MDRGI) 内。该 MDRGI 插入到染色体上保守基因 上。多位点序列型 (MLST) 分析表明，克隆扩张和水平转移都参与了 (L)变体的传播。这些发现揭示了 种中一种新的四环素耐药决定因素的出现，这可能有助于它们适应鸡体内的抗菌选择压力。
