The Partial 3′-Conserved Segment Duplications in the Integrons In6 from pSa and In7 from pDGO100 Have a Common Origin

Stokes, H. W.; Tomaras, Constantine; Parsons, Y. M.; Hall, Ruth M.

doi:10.1006/plas.1993.1032

Cited by 86 publications

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“…This integron has unusual structures showing the partial duplication of the 3'CS, containing the ORF341, and carrying the bla DHA-1 locus integrated into a secondary recombination site, downstream of ORF341. A similar structure was previously described for two other integrons, In6 and In7 [41,67,85]. Besides containing ORF341, these integrons also carry a different array of resistance genes integrated at the attI and at the secondary site downstream of ORF341.…”

Section: Clustering Of Resistance Genesmentioning

confidence: 88%

Importance of integrons in the diffusion of resistance

2001

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Summary -Horizontal transfer of resistance genes is a successful mechanism for the transmission and dissemination of multiple drug resistance among bacterial pathogens. The impact of horizontally transmitted genetic determinants in the evolution of resistance is particularly evident when resistance genes are physically associated in clusters and transferred en bloc to the recipient cell. Recent advances in the molecular characterisation of antibiotic resistance mechanisms have highlighted the existence of genetic structures, called integrons, involved in the acquisition of resistance genes. These DNA elements have frequently been reported in multi-drug resistant strains isolated from animals and humans, and are located either on the bacterial chromosome or on broad-host-range plasmids. The role of integrons in the development of multiple resistance relies on their unique capacity to cluster and express drug resistance genes. Moreover, the spread of resistance genes among different replicons and their exchange between plasmid and bacterial chromosome are facilitated by the integration of integrons into transposable elements. The association of a highly efficient gene capture and expression system, together with the capacity for vertical and horizontal transmission of resistance genes represents a powerful weapon used by bacteria to combat the assault of antibiotics. antimicrobial resistance / integron / transposon / horizontal gene transferRésumé -Importance des intégrons dans la diffusion de la résistance. Le transfert horizontal de gènes est un mécanisme efficace pour la transmission et la dissémination, parmi les agents pathogènes bactériens, de résistances multiples aux antibiotiques. L'impact des déterminants génétiques transmis horizontalement dans l'évolution de la résistance est particulièrement évident lorsque les gènes de résistance sont physiquement regroupés, et transférés en bloc à la cellule réceptrice. Des avancées récentes dans la caractérisation moléculaire des mécanismes de résistance aux antibiotiques ont mis en évidence l'existence de structures génétiques, appelées intégrons, impliqués dans l'acquisition de gènes de résistance. Ces éléments d'ADN ont été fréquemment observés dans des souches bactériennes multi-résistantes isolées chez des animaux ou chez des humains, localisés soit sur le chromosome bactérien, soit sur des plasmides à large spectre d'hôte. Le rôle des intégrons dans le développement de la multi-résistance repose sur leur capacité unique à former des clusters de gènes et à exprimer des gènes Vet. Res. 32 (2001) 243-259 243

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Section: Clustering Of Resistance Genesmentioning

confidence: 88%

Importance of integrons in the diffusion of resistance

2001

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“…Common regions were first discovered and reported in the early 1990s as a DNA sequence of 2,154 bp that was found in two complex class 1 integrons, In6 and In7 (93). These arrays possess partial duplications of the 3Ј conserved sequence of the class 1 integrons (Fig.…”

Section: Crs and Their Discoverymentioning

confidence: 99%

“…Accordingly, it was unexpected to find noncassette resistance genes closely associated with integron structures. Searches of available databases in 1993 detected only one other sequence with high identity to the CR, i.e., a 349-bp section of the small nonconjugative plasmid, RSF1010 (93). This plasmid is a broad-host-range (incQ) plasmid that confers resistance to sulfonamide and streptomycin and has been the basis of numerous broad-host-range vectors for recombinant DNA manipulation.…”

Section: Crs and Their Discoverymentioning

confidence: 99%

“…D37825). Integrons In6 and In7 were discovered on plasmids pSa and pDG0100, respectively, with pDG0100 being a 120-kb incC group plasmid and pSa a 39-kb incW group plasmid (93). Recently, a retrospective study found an integron that is virtually identical to In6 on the incU group plasmid pAR-32, which confers resistance to sulfonamide, chloramphenicol, and streptomycin.…”

Section: Crs and Their Discoverymentioning

confidence: 99%

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IS CR Elements: Novel Gene-Capturing Systems of the 21st Century?

Toleman

Bennett

Walsh

2006

Microbiol Mol Biol Rev

512

481

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SUMMARY “Common regions” (CRs), such as Orf513, are being increasingly linked to mega-antibiotic-resistant regions. While their overall nucleotide sequences show little identity to other mobile elements, amino acid alignments indicate that they possess the key motifs of IS91-like elements, which have been linked to the mobility ent plasmids in pathogenic Escherichia coli. Further inspection reveals that they possess an IS91-like origin of replication and termination sites (terIS), and therefore CRs probably transpose via a rolling-circle replication mechanism. Accordingly, in this review we have renamed CRs as ISCRs to give a more accurate reflection of their functional properties. The genetic context surrounding ISCRs indicates that they can procure 5′ sequences via misreading of the cognate terIS, i.e., “unchecked transposition.” Clinically, the most worrying aspect of ISCRs is that they are increasingly being linked with more potent examples of resistance, i.e., metallo-β-lactamases in Pseudomonas aeruginosa and co-trimoxazole resistance in Stenotrophomonas maltophilia. Furthermore, if ISCR elements do move via “unchecked RC transposition,” as has been speculated for ISCR1, then this mechanism provides antibiotic resistance genes with a highly mobile genetic vehicle that could greatly exceed the effects of previously reported mobile genetic mechanisms. It has been hypothesized that bacteria will surprise us by extending their “genetic construction kit” to procure and evince additional DNA and, therefore, antibiotic resistance genes. It appears that ISCR elements have now firmly established themselves within that regimen.

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“…In S. Agona strains, three SGI1 variant antibiotic resistance gene clusters, SGI1-A (complex class 1 integron containing the entire antibiotic resistance gene cluster), SGI1-D (class 1 integron containing only the aadA2 gene cassette), and SGI1-G (class 1 integron containing only the bla PSE-1 gene cassette), the 3'-CS (designated 3'-CS1) is followed by a 2 154-bp common region (CR) originally described in In6 and In7 [112,133]. There is a unique region adjacent to the CR that includes dfrA10 (Tm resistance), as in In7 [112].…”

Section: Emergence Of Variant Sgi1 Antibiotic Resistance Gene Clustermentioning

confidence: 99%

Emergence of Salmonella epidemics: The problems related to Salmonella enterica serotyp Enteritidis and multiple antibiotic resistance in other major serotypes

Cloeckaert²,

2005

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-Two major changes in the epidemiology of salmonellosis occurred in the second half of the 20th century: the emergence of food-borne human infections caused by S. Enteritidis and by multiple-antibiotic resistant strains of Salmonella. This review updates information on the S. Enteritidis pandemic and focuses on the emergence of Salmonella, carrying the SGI1 antibiotic resistance gene cluster, resistant to extended-spectrum cephalosporins, or resistant to fluoroquinolones. The factors responsible for the emergence of these Salmonella strains could be either of human origin or related to bacterial genome evolution. However, our increasing understanding of the molecular fluidity of the genome shows that any attempt to counteract bacteria results in further bacterial evolution or adaptation of other bacteria to take place in the new free ecological niche. In these conditions, we can ask who is faster: humans who want to eliminate bacterial pathogens or bacteria that continuously evolve to gain new niches.

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The Partial 3′-Conserved Segment Duplications in the Integrons In6 from pSa and In7 from pDGO100 Have a Common Origin

Cited by 86 publications

References 0 publications

Importance of integrons in the diffusion of resistance

Importance of integrons in the diffusion of resistance

IS CR Elements: Novel Gene-Capturing Systems of the 21st Century?

Emergence of Salmonella epidemics: The problems related to Salmonella enterica serotyp Enteritidis and multiple antibiotic resistance in other major serotypes

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