Description of In116, the first blaCTX-M-2-containing complex class 1 integron found in Morganella morganii isolates from Buenos Aires, Argentina

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Abstract
Objectives: We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods: bla genes and class 1 integron elements were detected by PCR and DNA–DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions: A class 1 integron (In116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 β-lactamase. The variable region of In116 contains aacA4, blaOXA-2 and orfD cassettes. Downstream of the 3′-conserved-segment (3′-CS), an orf513-containing common region is followed by blaCTX-M-2 and flanking regions, having 96–99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3′-CS (3′-CS2), and the absence of 59-base element or IS-like structures upstream of blaCTX-M-2.