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http://hdl.handle.net/10773/11067
Title: | Resistance to Broad-Spectrum Antibiotics in Aquatic Systems: Anthropogenic Activities Modulate the Dissemination of blaCTX-M-Like Genes |
Author: | Tacão, Marta Correia, António Henriques, Isabel |
Issue Date: | Jun-2012 |
Publisher: | American Society for Microbiology |
Abstract: | We compared the resistomes within polluted and unpolluted rivers, focusing on extended-spectrum beta-lactamase (ESBL) genes, in particular blaCTX-M. Twelve rivers from a Portuguese hydrographic basin were sampled. Physicochemical and microbiological parameters of water quality were determined, and the results showed that 9 rivers were classified as unpolluted (UP) and that 3 were classified as polluted (P). Of the 225 cefotaxime-resistant strains isolated, 39 were identified as ESBL-producing strains, with 18 carrying a blaCTX-M gene (15 from P and 3 from UP rivers). Analysis of CTX-M nucleotide sequences showed that 17 isolates produced CTX-M from group 1 (CTX-M-1, -3, -15, and -32) and 1 CTX-M that belonged to group 9 (CTX-M-14). A genetic environment study revealed the presence of different genetic elements previously described for clinical strains. ISEcp1 was found in the upstream regions of all isolates examined. Culture-independent blaCTX-M-like libraries were comprised of 16 CTX-M gene variants, with 14 types in the P library and 4 types in UP library, varying from 68% to 99% similarity between them. Besides the much lower level of diversity among CTX-M-like genes from UP sites, the majority were similar to chromosomal ESBLs such as blaRAHN-1. The results demonstrate that the occurrence and diversity of blaCTX-M genes are clearly different between polluted and unpolluted lotic ecosystems; these findings favor the hypothesis that natural environments are reservoirs of resistant bacteria and resistance genes, where anthropogenic-driven selective pressures may be contributing to the persistence and dissemination of genes usually relevant in clinical environments. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/11067 |
DOI: | 10.1128/AEM.00359-12 |
ISSN: | 0099-2240 |
Appears in Collections: | CESAM - Artigos DBio - Artigos Ria de Aveiro - Artigos |
Files in This Item:
File | Description | Size | Format | |
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5_Resistance to Broad-Spectrum.pdf | 583.86 kB | Adobe PDF | View/Open |
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