摘要
为了研究动物园禽类散养场分离菌对替加环素敏感性及其耐药机制,2019年从某市动物园禽类散养场采集的1只健康珍珠鸡粪便样品中分离获得分离菌,通过常规细菌分离纯化、革兰染色镜检和全自动细菌鉴定仪鉴定,以及序列比对确定该菌株为印地不动杆菌(LYS68A)。采用微量肉汤稀释法测定菌株对8种抗菌药物的敏感性,并通过全基因组测序和比较基因组学分析该菌株的耐药特征。药敏试验及PCR检测发现,尽管该菌株对多西环素和替加环素高度敏感,但却携带对替加环素耐药的tet(X3)基因。进一步全基因组测序发现菌株LYS68A未携带耐药质粒,其染色体上共携带tet(X3)、tet(X6)、floR、sul1、aadA2、dfrA12、aph(3’)-I、mphE和sul2等9个耐药基因,构成了一个29252 bp的多重耐药区并以一个整体插入到基因组tRNA-Gly的上游。耐药基因tet(X6)的基因环境(hp-tet(X6)-α/βhydrolase-GMP synthase)与2020年在1株奇异变形杆菌中发现的tet(X6)的基因环境同源性高达99%,推测其是通过ISVsa3和假定蛋白(hp)之间的热点区域(TCTTCC)经同源重组获得。耐药基因tet(X3)的基因环境与质粒p34AB(MK134375)中tet(X3)的上、下游序列高度相似,主要区别是前者仅一侧含有ISVsa3,而另一侧的插入序列在同源重组后缺失,结果导致tet(X3)失去独立在菌属间水平传播能力。本试验首次在1株替加环素敏感的禽源印地不动杆菌菌株LYS68A的染色体上同时检出tet(X6)和tet(X3)基因,且两种tet(X)的变异体主要通过菌属间的同源重组获得。
To analyze the sensitivity and drug resistant mechanism to tigecycline of free-range poultry park in zoo,LYS68 A was obtained from a guinea fowl feces sample in 2019.It was isolated and purified by conventional methods.Antimicrobial susceptibility to 8 antibiotics were determined with broth micro-dilution method.PCR and sequencing were used to detect the tigecycline resistance gene tet(X).The characteristics of LYS68 A were analyzed by whole genome sequencing and comparative genomics.LYS68 A was identified as Acinetobacter indicus by sequence alignment.Although the strain was highly sensitive to doxycycline and tigecycline,tet(X3)gene was found to be resistant to tigecycline.Whole genome sequencing showed that LYS68 A did not carry drug-resistant plasmid,and its chromosomes carried a total of 9 drug resistance genes,including floR,tet(X6),sul1,aadA2,dfrA12,aph(3′)-I,tet(X3),mphE,sul2.A 29252 bp multidrug resistant region was constructed and inserted as a whole into the upstream of the genome tRNA-Gly.It inserts as a whole into one of hot spots the genome,upstream of tRNA-Gly.The gene environment of drug resistance gene tet(X6)(hp-tet(X6)-α/βhydrolyse-GMP synthase)was 99%homologous to the gene environment of tet(X6)found in a strain of Proteus genomospecies in 2020.It was assumed that it was obtained by homologous recombination of the hot spot region(TCTTCC)between ISVsa3and the hypothetical protein(hp).The gene environment of the drug resistance gene tet(X3)was highly similar to that of the upstream and downstream sequences of tet(X3)in plasmid p34AB(MK134375).The main difference was that only one side of the former contained ISVsa3,while the insertion sequence on the other side was missing after homologous recombination,resulting in the loss of the ability of tet(X3)to independently transmit horizontally among bacteria.In conclusion,for the first time,tet(X6)and tet(X3)gene were detected simultaneously on the chromosome of a tigecycline sensitive avian Acinetobacter indicus LYS68A,and the two tet(X)variants
作者
李垠树
赵冰
孙华润
何坤
许慧
梁玉蕾
胡功政
苑丽
LI Yinshu;ZHAO Bing;SUN Huarun;HE Kun;XU Hui;LIANG Yulei;HU Gongzheng;YUAN Li(College of Animal Medicine,Henan Agricultural University,Zhengzhou 450046,China)
出处
《中国兽医学报》
CAS
CSCD
北大核心
2022年第8期1620-1625,共6页
Chinese Journal of Veterinary Science
基金
国家自然科学基金面上资助项目(31772800)。
