A new trimethoprim resistance gene, dhfrX, in the In7 integron of plasmid pDGO100

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

doi:10.1128/aac.35.11.2436

Cited by 47 publications

(49 citation statements)

References 21 publications

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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%

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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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Section: Emergence Of Variant Sgi1 Antibiotic Resistance Gene Clustermentioning

confidence: 99%

“…There is a unique region adjacent to the CR that includes dfrA10 (Tm resistance), as in In7 [112]. Following this unique region is a second partial copy of the 3'-CS, designated 3'-CS2.…”

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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“…The integron system associated with the Tn2l-group of transposons has been responsible for the accumulation of resistance mechanisms to sulphonamides [45], ,3-lactams [50], aminoglycosides [51], heavy metals [52] and disinfectants [25] as well as the insertion of the dhfr genes encoding for the DHFR types lIc, V [23], VII [25], X [32]. Recently the dhfrla has been found in Tn2I inserted as a gene-cassette that has been shown to be associated with Tn7; however, the integrase of Tn7 seems to have undergone a deletion that has rendered it inoperative [29,32].…”

Section: Discussionmentioning

confidence: 99%

“…The DHFR types Ia, IIc, V, VII and X have been found as gene-cassettes located at the integron-associated active recombination locus of Tn2l-like transposons [25,32]. The DHFR lb has only been characterized as part of a Tn7-like transposon [33].…”

Section: Introductionmentioning

confidence: 99%

Trimethoprim resistant dihydrofolate reductases in normal faecal flora isolated in India

Tait

Amyes

1994

Epidemiol. Infect.

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SUMMARYA high incidence of resistance to trimethoprim has been shown in the normal faecal flora in a population in south India. The dihydrofolate reductase (dhfr) genes mediating transferable resistance to trimethoprim have been identified.Unusually, in this study, the dhfrV was shown to be the predominant resistance gene (dhfrV 50 % of transconjugants, dhfrla 30%), the dhfrlb was also detected being distinguished from the dhfrV by an oligo-probe. However, when nontransferable resistance was considered, the dhfrIa was the most prevalent of the dhfrs identified. All those plasmids harbouring the dhfrla were shown to possess Tn7. All the plasmids that probed positive for the dhfrV and the dhfrlb were shown to be associated with the integrase of the Tn2l-like transposons, but 8 of the dhfrV genes were not associated with the Tn2l resolvase. The dhfrIV was shown to be present in all seven plasmids that produced low level trimethoprimresistance. The dhfrV, first characterized in Sri Lanka, would seem to have a local distribution in this region of Asia but is distinguishable from the dhfrlb only by the use of an oligo-probe.

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“…Fifteen of these trimethoprim resistant enzymes have been identified in Enterobacteria and have been characterized according to their biochemistry and DNA sequence. They are the Ia [3], lb [4], Ila [5], Ilb [6], Ile [7], Illa [8], IIIb [9], IIIc [10] renamed the type VIII [11], IV [12], V [13], VI [14], VII [15], IX [16], X [17] and XII [18].…”

Section: Introductionmentioning

confidence: 99%

Prevalence and genetic location of non-transferable trimethoprim resistant dihydrofolate reductase genes in South African commensal faecal isolates

et al. 1995

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SUMAIARYIn a recent survey of trimethoprim resistance, 357 Gram-negative aerobic organisms were isolated from healthy volunteers from rural and urban populations in South Africa. Trimethoprim resistance did not transfer to an Escherichia coli J62-2 recipient strain by conjugation in a liquid mating in 161 (45 1 %) of the isolates. These isolates which did not transfer their resistance were probed with intragenic oligonucleotide probes for the types Ia, Ib, Illa, V, VI, VII, VIII, IX, X and XII dihydrofolate reductase genes. Contrary to all previous data, the most prevalent dihydrofolate reductase gene in this group of non-transferable isolates which hybridized, was the type VII (38%) followed by the type Ia (25%), lb (12%), V (1-7%) and VIII (1-2%). None of the strains hybridized to the types Illa, VI, XI, X and the XII dihydrofolate reductase probes. Southern blots of plasmid and chromosomal DNA from selective isolates revealed that the type VII dihydrofolate reductase genes were located on the chromosome and were associated with the integrase gene of Tn2l. However, the type lb and Vr dihydrofolate reductase genes were all found on plasmids which could not be mobilized. The type Ia dihydrofolate reductase genes were found on both nontransferable plasmids and on the chromosome. The nature of the genetic structures associated with a dihydrofolate reductase gene strongly affects the means of spread of the gene in a population.

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A new trimethoprim resistance gene, dhfrX, in the In7 integron of plasmid pDGO100

Cited by 47 publications

References 21 publications

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

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

Trimethoprim resistant dihydrofolate reductases in normal faecal flora isolated in India

Prevalence and genetic location of non-transferable trimethoprim resistant dihydrofolate reductase genes in South African commensal faecal isolates

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