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At least 397 records · Page 22Linked to original sources
PubMed1996

An inverted repeat in the Tn21 integron determines the production of stem-loop DNA.

A 580-bp-long stem-loop DNA (sl-DNA) molecule was produced by a recombinant plasmid containing complete int and aadA genes from the transposon Tn21 cloned in the vector pUC18. A 50-bp-long inverted repeat found near the int gene stop codon could be involved in the generation of the sl-DNA molecule. cloning of the dhfrII gene between the plasmid replication origin and this IR produced an extended sl-DNA including the dhfrII gene. Tn21 recombination hot spot 2 was also able to direct the production of sl-DNA.

Codon↗
PubMed1997

Origins of the mobile gene cassettes found in integrons.

Many of the acquired antibiotic resistance genes found in enterobacteria and pseudomonads are part of small mobile elements known as gene cassettes, and other genes are also likely to be found in cassettes. The origins of the genes and the recombination sites that make up cassettes are not known, but recent analyses of available data suggest that cassettes may be ancient structures, and some hypotheses for how they are formed can now be examined.

DNA Transposable Elements↗
PubMed2003

Characterization of antimicrobial resistance, plasmids, and gene cassettes in Shigella spp. from patients in vietnam.

The objective of the study was to investigate antimicrobial resistance, plasmids and class 1 integrons in 150 Shigella strains isolated from patients with diarrhea in Vietnam. Most isolates were resistant to the majority of antimicrobial agents used for treatment in the isolation areas and 90% were resistant to three or more antibiotics. A total of 20 strains yielded class 1 integrons, which harbored oxa1, dfrA, orfF, and aadA gene cassettes. The most common gene cassette, aadA2, was always located closest to the 3' conserved segment of the integrons and oxa1 and dfrA closest to the 5' end. Plasmid profiles of the 20 class 1 integron-positive strains all contained more than one plasmid, and 14 different profiles were found. No correlation was found between species, antibiograms, plasmid profiles, or presence of class 1 integrons. Conjugation resulted in 25 transconjugants, which all were resistant to four or more antimicrobial agents and all harbored at least one plasmid (>60 kb). Class 1 integrons were detected in 64% of the transconjugants. Phenotypic resistance pattern and plasmid profiles of the transconjugants seemed independent of the presence of an integron. Class 1 integrons seemed of less importance in phenotypic antibiograms and in transfer of resistance genes than conjugative plasmids.

Anti-Bacterial Agents↗
PubMed2005

Molecular basis of resistance to trimethoprim, chloramphenicol and sulphonamides in Bordetella bronchiseptica.

OBJECTIVES: To date, little is known about the molecular basis of antimicrobial resistance in Bordetella bronchiseptica, an important respiratory tract pathogen in pigs, dogs and cats. The aim of this study was to identify genes coding for trimethoprim resistance present in porcine B. bronchiseptica and to determine their localization, transferability and association with other resistance genes. METHODS: Six B. bronchiseptica isolates with elevated MICs of trimethoprim were investigated by PCR for the presence of trimethoprim resistance genes and their association with class 1 integrons. The amplicons obtained were cloned and sequenced. Plasmid localization of these integrons was confirmed by transformation and conjugation. Isolates carrying the same integron were compared for their genetic relatedness by XbaI and SpeI pulsed-field gel electrophoresis (PFGE). RESULTS: Five B. bronchiseptica isolates carried a class 1 integron with two gene cassettes, one carrying the trimethoprim resistance gene dfrA1 and the other the chloramphenicol resistance gene catB3. This integron was present on a common conjugative plasmid in four of the five isolates and on the chromosome in the remaining isolate. All five B. bronchiseptica isolates proved to be related on the basis of their PFGE patterns. Another isolate had a class 1 integron with a dfrB1 and a catB2 cassette on a structurally different conjugative plasmid. The sulphonamide resistance gene sul1 was detected in the 3'-conserved segment of both types of integrons. CONCLUSIONS: This is the first report of trimethoprim, chloramphenicol and sulphonamide resistance genes and class 1 integrons in B. bronchiseptica isolates.

Animals↗