Antimicrobial resistance is a “One Health” issue that requires improved knowledge of the presence and abundance of resistant bacteria in the environment. Extended-spectrum cephalosporins (ESCs) are critically important antibiotics (CIAs), and resistance to these CIAs is often encoded by beta-lactamase genes borne on conjugative plasmids. We thus decided to characterise 21 plasmids of ESC-resistant Escherichia coli randomly selected from isolates previously obtained from river water collected in a rural area in western France. The plasmids encoding ESC resistance were sequenced to investigate the diversity of the genes encoding ESC resistance and their genetic context.

Sequences revealed that eleven IncI1 pMLST3 plasmids carried the bla_CTX-M-1 and sul2 genes, and some of them also had the tet(A), aadA5 or dfrA17 genes. The bla_CTX-M-1 gene was also detected on an IncN plasmid. Five plasmids obtained from four rivers contained bla_CTX-M-14, either on IncI1 or on IncFII plasmids. Two strains from two rivers contained bla_CTX-M-15 on IncN pMLST7 plasmids, with qnrS1 and dfrA14 genes. One plasmid contained the bla_CTX-M-55, a bla_TEM-1B-like, and fosA genes. One plasmid contained the bla_CMY-2 gene.

The diversity of the genes and plasmids of the resistant bacteria isolated from French rivers is probably related to the various animal and human origins of the isolated bacteria.

抗菌素耐药性是“一个健康问题”，需要对环境中耐药菌的存在和丰富性有更多的了解。广谱头孢菌素（ESC）是至关重要的抗生素（CIA），对这些CIA的抗性通常由结合质粒上携带的β-内酰胺酶基因编码。因此，我们决定表征21种抗ESC大肠杆菌的质粒，这些质粒随机选自先前从法国西部农村地区收集的河水中分离的菌株。对编码ESC抗性的质粒进行测序，以研究编码ESC抗性的基因的多样性及其遗传背景。

序列显示，有11个IncI1 pMLST3质粒带有bla _CTX-M-1和sul2基因，其中一些还具有tet（A），aadA 5或dfrA17基因。所述BLA _CTX-M-1上的IncN质粒也检测基因。从四个河流获得的五个质粒在IncI1或IncFII质粒上均包含bla _CTX-M-14。来自两条河流的两个菌株在IncN pMLST7质粒上包含bla _CTX-M-15，具有qnrS1和dfrA14基因。一种质粒包含bla _{CTX-M - 55}，bla _TEM-1B样和fosA基因。一种质粒包含bla _CMY-2基因。

从法国河中分离出的抗性细菌的基因和质粒的多样性可能与分离出的细菌的各种动物和人类起源有关。