Transferable plasmid-mediated quinolone resistance in association with extended-spectrum β-lactamases and fluoroquinolone-acetylating aminoglycoside-6′-N-acetyltransferase in clinical isolates of Vibrio fluvialis
Transferable plasmid-mediated quinolone resistance in association with extended-spectrum β-lactamases and fluoroquinolone-acetylating aminoglycoside-6′-N-acetyltransferase in clinical isolates of Vibrio fluvialis
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DOI：
10.1016/j.ijantimicag.2011.04.013
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发表时间：
2011-08-01
影响因子：
10.8
通讯作者：
Ramamurthy, T.
中科院分区：
文献类型：
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作者：
Chowdhury, Goutam;Pazhani, Gururaja Perumal;Ramamurthy, T.
河流弧菌可引起人类霍乱样腹泻，是印度加尔各答急性腹泻的病原体之一，对许多抗菌药物具有耐药性。发现两种对氟喹诺酮类和β-内酰胺类抗生素具有抗性的河流弧菌分离株在喹诺酮类耐药决定区（QRDRs）的GyrA位置83和ParC位置85处具有突变，并且携带含有喹诺酮类耐药基因qnrA 1的150 kb质粒，编码环丙沙星修饰酶的基因aac（6 ′）-Ib-cr和编码超广谱β-内酰胺酶如bla（SHV）和bla（CTX-M-3）的基因。当这个大质粒通过接合转移到大肠杆菌中时，接合子显示环丙沙星和诺氟沙星的最低抑制浓度增加10-75倍。qnrA 1基因被确定在一个复杂的sul 1型整合子的transconjugants质粒。Southern杂交和qnrA 1及其侧翼区的序列分析证实了aac（6 '）-Ib-cr和bla（CTX-M-3）的存在，但这些与sul 1型整合子无关。脉冲场凝胶电泳（PFGE）显示，两个河流弧菌分离株属于不同的克隆。虽然在亚洲国家的肠道细菌中已经报道了许多qnr等位基因的存在，但这是关于qnrA 1在印度出现的第一份报告。qnrA 1沿着aac（6 '）-Ib-cr和bla（CTX-M-3）基因在移动的质粒上可能传播到该区域内处于氟喹诺酮类和β-内酰胺类抗菌剂选择压力下的其他细菌种属。(c)2011年爱思唯尔B。和国际化疗学会。All rights reserved.
Vibrio fluvialis, which causes cholera-like diarrhoea in humans, is one of the aetiological agents of acute diarrhoea in Kolkata, India, and is resistant to many antimicrobial agents. Two V. fluvialis isolates resistant to fluoroquinolones and beta-lactam antimicrobials were found to have mutations in the quinolone resistance-determining regions (QRDRs) of GyrA at position 83 and of ParC at position 85 as well as carrying a 150 kb plasmid harbouring the quinolone resistance gene qnrA1, the ciprofloxacin-modifying enzyme-encoding gene aac(6')-Ib-cr and genes encoding for extended-spectrum beta-lactamases such as bla(SHV) and bla(CTX-M-3). When this large plasmid was transferred to Escherichia coli by conjugation, the transconjugants showed a 10-75-fold increase in the minimum inhibitory concentrations of ciprofloxacin and norfloxacin. The qnrA1 gene was identified in a complex sul1-type integron in a plasmid of the transconjugants. Southern hybridisation and sequence analysis of qnrA1 and its flanking regions confirmed the presence of aac(6')-Ib-cr and bla(CTX-M-3) but these were not associated with the sul1-type integron. Pulsed-field gel electrophoresis (PFGE) revealed that the two V. fluvialis isolates belonged to different clones. Although the presence of many qnr alleles has been reported amongst enteric bacteria in Asian countries, this is the first report on the emergence of qnrA1 in India. qnrA1 along with aac(6')-Ib-cr and bla(CTX-M-3) genes on a mobile plasmid may spread to other bacterial species that are under the selective pressure of fluoroquinolones and beta-lactam antimicrobials in this region. (c) 2011 Elsevier B. V. and the International Society of Chemotherapy. All rights reserved.