Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China.
Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China.
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DOI：
10.1093/jac/dkv114
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
Hawkey PM
中科院分区：
文献类型：
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作者：
Zhong YM;Liu WE;Liang XH;Li YM;Jian ZJ;Hawkey PM
本研究的目的是确定产CTX-M大肠埃希菌ST 131菌株在中国中部健康受试者粪便标本中的流行率，并对克隆群进行分子表征。2013年11月至2014年1月对湖南省健康人群粪便标本进行产ESBL E.大肠杆菌CTX-M基因型及系统发育分析。通过PCR检测ST 131克隆群并表征抗生素耐药性、fimH、gyrA和parC等位基因、质粒介导的喹诺酮类耐药决定簇、毒力基因型和PFGE模式。在563例受试者中，287例（51.0%）存在粪便产ESBL E。coli中，所有菌株都能产生CTX-M酶。最常见的CTX-M基因型为CTX-M-14（48.4%）、CTX-M-15（27.5%）和CTX-M-27（15.0%）。在287株产CTX-M菌株中，32株（11.1%）属于ST 131克隆。O 16-ST 131菌株占优势（75%），含有fimH 41等位基因。其余8株（25%）ST 131分离株属于O25 b亚组，含有fimH 30或fimH 41。O25 b-ST 131分离株对环丙沙星的耐药率为100%，而O 16-ST 131分离株对环丙沙星的耐药率仅为8%。除1株外，所有O25 b-ST 131分离株均显示gyrA 1AB和parC 1aAB突变;大多数O 16-ST 131分离株均具有gyrA 1A和parC 1b突变。O 16-ST 131菌株的毒力基因型与O25 b-ST 131菌株的毒力基因型相似。在64%的相似性水平上，32个ST 131分离物形成一个大群。它们包括15个PFGE组（定义为相似性≥85%）。O 16-ST 131分离株已成为粪便产CTX-M大肠杆菌中ST 131分离株的主要类型。中国健康人群中的大肠杆菌。
The objectives of this study were to determine CTX-M-producing Escherichia coli ST131 strain prevalence in stool specimens from healthy subjects in central China and to molecularly characterize clonal groups. From November 2013 to January 2014, stool specimens from healthy individuals in Hunan Province were screened for ESBL-producing E. coli using chromogenic medium and CTX-M genotypes and phylogenetic groups were determined. ST131 clonal groups were detected by PCR and characterized for antibiotic resistance, fimH, gyrA and parC alleles, plasmid-mediated quinolone resistance determinants, virulence genotypes and PFGE patterns. Among 563 subjects, 287 (51.0%) exhibited the presence of faecal ESBL-producing E. coli, all of which produced CTX-M enzymes. The most common CTX-M genotypes were CTX-M-14 (48.4%), CTX-M-15 (27.5%) and CTX-M-27 (15.0%). Of the 287 CTX-M-producing isolates, 32 (11.1%) belonged to the ST131 clone. O16-ST131 isolates were dominant (75%) and contained the fimH41 allele. The remaining eight (25%) ST131 isolates were of the O25b subgroup and contained fimH30 or fimH41. Ciprofloxacin resistance was found in 100% of the O25b-ST131 isolates, whereas only 8% of the O16-ST131 isolates were resistant. All of the O25b-ST131 isolates except one showed gyrA1AB and parC1aAB mutations; most of the O16-ST131 isolates had gyrA1A and parC1b mutations. The virulence genotypes of O16-ST131 resembled those of the O25b-ST131 isolates. The 32 ST131 isolates formed one large group at the 64% similarity level. They comprised 15 PFGE groups (defined at ≥85% similarity). O16-ST131 isolates have emerged as the predominant type of ST131 isolate in faecal CTX-M-producing E. coli in healthy individuals in China.