Metallo-beta-lactamase-producing Escherichia coli in the sewage of Mexico City: where do they come from?

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From: Canadian Journal of Microbiology(Vol. 68, Issue 2)
Publisher: NRC Research Press
Document Type: Report
Length: 4,545 words
Lexile Measure: 1500L

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Abstract :

While monitoring the presence of antibiotic resistance in municipal wastewater bacteria from Mexico City, five Escherichia coli isolates were found to be resistant to carbapenems, antibiotics of "last resort" used mostly in hospitals. Further analysis revealed that these carbapenem-resistant isolates carried the gene encoding a metallobeta-lactamase, NDM-5. The gene was found to be beared by a large, ~145 kb conjugative plasmid, which also carries putative genes encoding resistance to sulfonamides, trimethoprim, tetracycline, ciprofloxacin, and chloramphenicol (although no phenotypic chloramphenicol resistance was detected) and quaternary-ammonium compounds. The plasmid also carried gene mobility determinants, such as integron integrase and two transposases. In addition to the direct public health threat posed by the presence of such multi-resistant organisms in wastewater released into the environment and used for crop irrigation; it is particularly concerning that carbapenem-resistant E. coli is rather rare in Mexican hospitals ( Key words: wastewater, Escherichia coli, antibiotic resistance, carbapenem resistance, NDM-5. Lors de la surveillance de la presence de la resistance aux antibiotiques dans les bacteries des eaux usees municipales de la ville de Mexico, cinq isolats d'Escherichia coli ont ete detectes comme etant resistants aux carbapenemes, des antibiotiques de utilises principalement dans les hopitaux. Une analyse plus poussee a revele que ces isolats resistants aux carbapenemes portaient le gene d'une metallo-beta-lactamase, la NDM-5. Il s'avere que ce gene est porte par un grand plasmide conjugatif de ~145 kb, qui porte egalement des genes putatifs codant la resistance aux sulfamides, au trimethoprime, a la tetracycline, a la ciprofloxacine, au chloramphenicol (bien qu'aucune resistance phenotypique au chloramphenicol n'ait ete detectee) et aux composes d'ammonium quaternaire. Le plasmide portait egalement des determinants de la mobilite des genes, comme une integrase d'integron et deux transposases. Outre la menace directe pour la sante publique que represente la presence de tels organismes multiresistants dans les eaux usees rejetees dans l'environnement et utilisees pour l'irrigation des cultures, il est particulierement inquietant de constater qu'E. coli resistant aux carbapenemes est plutot rare dans les hopitaux mexicains ( Mots-cles : eaux usees, Escherichia coli, resistance aux antibiotiques, resistance aux carbapenemes, NDM-5.

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Gale Document Number: GALE|A693514957