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J Antimicrob Chemother. 2005 Nov;56(5):819-26. Epub 2005 Sep 27.

Characterization of the highly variable region surrounding the bla(CTX-M-9) gene in non-related Escherichia coli from Barcelona.

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Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain.



The dispersion of a clone, a plasmid or a mobile element carrying the bla(CTX-M-9) gene was evaluated in 30 Escherichia coli strains isolated in Barcelona between 1996 and 1999. The presence of the previously described orf513-bearing class 1 integron, In60, carrying the bla(CTX-M-9) gene, was also studied.


The clonality was analysed by pulsed-field gel electrophoresis. Plasmid analysis was performed by S1 digestion and hybridization with the CTX-M-9 probe. PCR mapping using specific designed primers was used to study the presence of In60 and In60-like structures.


The clonality between the 30 strains was minor. The size of bla(CTX-M-9) carrying plasmids ranged between approximately 80 and 430 kb. One strain produced only a chromosome-encoded CTX-M-9 beta-lactamase. Thirty-six per cent of the strains showed differences with respect to the In60 structure due to an insertion or deletion events.


These findings suggest that the bla(CTX-M-9) gene may be carried by a mobile element that disperses it between plasmids. The fast dispersion of the CTX-M-9 enzyme could therefore be due to both diffusion of plasmids and mobile elements.

[Indexed for MEDLINE]

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