Chouchani Chedly, Marrakchi Rim, Henriques Isabel, Correia António
Université de Carthage, Institut Supérieur des Sciences et Technologies de l'Environnement de Borj-Cedria, Technopôle de Borj-Cedria, Hammam-Lif, Tunisia.
Scand J Infect Dis. 2013 Feb;45(2):95-103. doi: 10.3109/00365548.2012.717712. Epub 2012 Sep 19.
Antibiotic-resistant bacteria have been surveyed widely in water bodies, but few studies have determined the diversity of antibiotic-resistant bacteria in river waters. This study was undertaken to investigate the origin of resistance among polluted river bacterial isolates in Tunisia.
In this study 128 isolates resistant to β-lactam antibiotics were obtained from 2 polluted rivers in the north of Tunisia. Isolates were identified using Phoenix phenotyping criteria. The occurrence of bla(TEM), bla(SHV), bla(CTX-M), bla(CMY), bla(VIM), and bla(IMP) was studied by polymerase chain reaction (PCR) amplification and sequencing, and the genetic relatedness of the 16 IMP-producing Klebsiella pneumoniae isolates was analyzed by comparison of XbaI pulsed-field gel electrophoresis (PFGE) profiles.
Using Phoenix phenotyping criteria, diverse genera of bacteria were identified with different rates of prevalence and with different minimum inhibitory concentrations against different antibiotics. The occurrence of bla(TEM), bla(SHV), bla(CTXM), bla(CMY), bla(VIM), and bla(IMP) genes was confirmed. The DNA sequences upstream and downstream of bla(IMP) genes were determined, revealing that all IMP-encoding genes constituted the first cassette of class 1 integrons, followed by aacA gene cassettes encoding aminoglycoside resistance. Comparison of PFGE profiles showed that only 2 of the isolates were clonal, the other 14 displaying unique profiles. The bla(CTX-M) gene was the most dominant of the extended-spectrum β-lactamase (ESBL) genes, while the bla(TEM) gene was the second-most dominant.
The discovery of highly diverse ESBL-producing bacteria and metallo-β-lactamases, particularly bla(IMP), in polluted river water raises alarms with regard to the potential dissemination of antibiotic-resistant bacteria in communities through river environments.
抗生素耐药菌已在水体中得到广泛调查，但很少有研究确定河水中抗生素耐药菌的多样性。本研究旨在调查突尼斯受污染河流细菌分离株的耐药起源。
在本研究中，从突尼斯北部的两条受污染河流中获得了128株对β-内酰胺类抗生素耐药的分离株。使用Phoenix表型分析标准对分离株进行鉴定。通过聚合酶链反应（PCR）扩增和测序研究bla(TEM)、bla(SHV)、bla(CTX-M)、bla(CMY)、bla(VIM)和bla(IMP)的出现情况，并通过比较XbaI脉冲场凝胶电泳（PFGE）图谱分析16株产IMP的肺炎克雷伯菌分离株的遗传相关性。
使用Phoenix表型分析标准，鉴定出了不同属的细菌，其流行率不同，对不同抗生素的最低抑菌浓度也不同。证实了bla(TEM)、bla(SHV)、bla(CTX-M)、bla(CMY)、bla(VIM)和bla(IMP)基因的出现。确定了bla(IMP)基因上下游的DNA序列，揭示所有编码IMP的基因构成1类整合子的第一个盒式结构，随后是编码氨基糖苷耐药性的aacA基因盒式结构。PFGE图谱比较显示，只有2株分离株是克隆性的，其他14株显示出独特的图谱。bla(CTX-M)基因是超广谱β-内酰胺酶（ESBL）基因中最主要的，而bla(TEM)基因是第二主要的。
在受污染的河水中发现高度多样化的产ESBL细菌和金属β-内酰胺酶，特别是bla(IMP)，这就抗生素耐药菌通过河流环境在社区中潜在传播发出了警报。
