Preclinical class 1 integron with a complete Tn402-like transposition module.

The presence of integrons was assessed in gut bacteria isolated from wild-caught prawns. A pseudomonad was recovered that contained a Tn402-like class 1 integron with a complete transposition module and two gene cassettes. One cassette was identical to a previously described cassette from a chromosomal class 3 integron in Delftia tsuruhatensis.

Mobilization of a Tn402-like class 1 integron with a novel cassette array via flanking miniature inverted-repeat transposable element-like structures.

A Tn402-like class 1 integron was recovered from a prawn-associated bacterium. One of its cassettes included methionine sulfoxide reductase genes, the first example of such genes being captured by an integron. The integron was flanked by direct repeats that resemble miniature inverted-repeat transposable element sequences.

Evidence for dynamic exchange of qac gene cassettes between class 1 integrons and other integrons in freshwater biofilms.

Class 1 integrons carried by pathogens have acquired over 100 different gene cassettes encoding resistance to antimicrobial compounds, helping to generate a crisis in the management of infectious disease. It is presumed that these cassettes originated from environmental bacteria, but exchange of gene cassettes has surprisingly never been demonstrated outside laboratory or clinical contexts. We aimed to identify a natural environment where such exchanges might occur, and determine the phylogenetic range of participating integrons.

Gene cassettes encoding resistance to quaternary ammonium compounds: a role in the origin of clinical class 1 integrons?

DNA sequencing, phylogenetic and mapping studies suggest that the class 1 integron found in pathogens arose when one member of the diverse family of environmental class 1 integrons became embedded into a Tn402 transposon. However, the timing of this event and the selective forces that first fixed the newly formed element in a bacterial lineage are still unknown. Biocides have a longer use in clinical practice than antibiotics, and a qac (quaternary ammonium compound) resistance gene, or remnant thereof, is a normal feature of class 1 integrons recovered from clinical isolates.

An enhanced miniaturized assay for antimicrobial prospecting.

Bioprospecting for novel antimicrobials increasingly relies on extremely small samples unsuitable for conventional bulk extraction and assay. We developed a microtitre plate assay for minimal amounts of test materials which is rapid, extremely sensitive, allows time-course analysis and reduces false negatives. Developed for the analyses of antimicrobial sensitivity and resistance, the technique is appropriate for assays where source materials are scarce.

Integrons in Xanthomonas: a source of species genome diversity.

Integrons are best known for assembling antibiotic resistance genes in clinical bacteria. They capture genes by using integrase-mediated site-specific recombination of mobile gene cassettes. Integrons also occur in the chromosomes of many bacteria, notably beta- and gamma-Proteobacteria.

Mobile gene cassettes: a fundamental resource for bacterial evolution.

Horizontal gene transfer increases genetic diversity in prokaryotes to a degree not allowed by the limitations of reproduction by binary fission. The integron/gene cassette system is one of the most recently characterized examples of a system that facilitates horizontal gene transfer. This system, discovered in the context of multidrug resistance, is recognized in a clinical context for its role in allowing pathogens to adapt to the widespread use of antibiotics.

Recombination activity of a distinctive integron-gene cassette system associated with Pseudomonas stutzeri populations in soil.

Class 1 integrons have strongly influenced the evolution of multiple antibiotic resistance. Diverse integrons have recently been detected directly in a range of natural environments. In order to characterize the properties of these environmental integrons, we sought to isolate organisms containing integrons from soils, which resulted in the isolation of Pseudomonas stutzeri strain Q.