Ewers Christa, Bethe Astrid, Stamm Ivonne, Grobbel Mirjam, Kopp Peter A, Guerra Beatriz, Stubbe Michael, Doi Yohei, Zong Zhiyong, Kola Axel, Schaufler Katharina, Semmler Torsten, Fruth Angelika, Wieler Lothar H, Guenther Sebastian
Institute of Hygiene and Infectious Diseases of Animals, Justus-Liebig-Universität Giessen, Frankfurter Str. 85-89, 35392 Giessen, Germany.
J Antimicrob Chemother. 2014 May;69(5):1224-30. doi: 10.1093/jac/dkt516. Epub 2014 Jan 6.
To discern the relevance of ST648 extended-spectrum β-lactamase (ESBL)-producing Escherichia coli as a putative new group of multiresistant and extraintestinal pathogenic strains in animals, its frequency, ESBL types, antimicrobial resistance patterns and virulence gene (VG) profiles should be determined and compared with ST131 strains from the same collection of strains.
ESBL-producing E. coli isolates (n = 1152), consecutively sampled from predominantly dogs, cats and horses between 2008 and 2011, were assigned to a phylogenetic group by PCR. Partial multilocus sequence typing was performed for group D and B2 strains and strains presumed to be D-ST648 and B2-ST131 were fully typed. ESBL genes and extraintestinal pathogenic E. coli (ExPEC)-like VGs were characterized by PCR and sequence analysis and antimicrobial resistance was determined by broth dilution. Clonal analysis was done by PFGE.
Forty (3.5%) ESBL-producing E. coli were determined as D-ST648, whereas B2-ST131 isolates occurred less frequently (2.8%). Although the predominant ESBL type in both groups was CTX-M-15 (72.5% versus 46.9%), ST648 strains from companion animals and horses displayed a lower variety of ESBL types (CTX-M-1, -3, -14, -15 and -61 versus CTX-M-1,-2,-14,-15,-27 and -55 and SHV-12). In contrast to ST131 strains, a higher proportion of ST648 strains showed resistance to most non-β-lactam antibiotics. Overall, VGs were less abundant in ST648 strains, although some strains had VG profiles comparable to those of ST131 strains. ExPEC-associated serotype O1:H6 was predominant (46.8%) among the ST648 strains. Some PFGE clusters comprised ST648 isolates from pets, horses and wild birds and humans included from previous studies.
Our findings demonstrate that certain subgroups of E. coli D-ST648-CTX-M may represent a novel genotype that combines multiresistance, extraintestinal virulence and zoonotic potential.
为了识别产超广谱β-内酰胺酶（ESBL）的大肠杆菌ST648作为动物中一种假定的新型多重耐药和肠外致病菌株群的相关性，应确定其频率、ESBL类型、抗菌药物耐药模式和毒力基因（VG）谱，并与来自同一菌株库的ST131菌株进行比较。
对2008年至2011年间从主要是狗、猫和马中连续采样的产ESBL的大肠杆菌分离株（n = 1152）通过PCR进行系统发育分组。对D组和B2组菌株以及推测为D-ST648和B2-ST131的菌株进行部分多位点序列分型。通过PCR和序列分析对ESBL基因和类肠外致病性大肠杆菌（ExPEC）VG进行表征，并通过肉汤稀释法测定抗菌药物耐药性。通过脉冲场凝胶电泳（PFGE）进行克隆分析。
40株（3.5%）产ESBL的大肠杆菌被确定为D-ST648，而B2-ST131分离株出现频率较低（2.8%）。尽管两组中主要的ESBL类型均为CTX-M-15（分别为72.5%和46.9%），但来自伴侣动物和马的ST648菌株显示出的ESBL类型较少（CTX-M-1、-3、-14、-15和-61，而CTX-M-1、-2、-14、-15、-27和-55以及SHV-12）。与ST131菌株相比，更高比例的ST648菌株对大多数非β-内酰胺类抗生素耐药。总体而言，ST648菌株中的VG较少，尽管一些菌株的VG谱与ST131菌株相当。ExPEC相关血清型O1:H6在ST648菌株中占主导（46.8%）。一些PFGE簇包含来自宠物、马和野生鸟类以及先前研究中的人类的ST648分离株。
我们的研究结果表明，大肠杆菌D-ST648-CTX-M的某些亚组可能代表一种结合了多重耐药性、肠外毒力和人畜共患病潜力的新型基因型。
