Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Integrons”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed2003

Comparative genome analysis of Vibrio vulnificus, a marine pathogen.

The halophile Vibrio vulnificus is an etiologic agent of human mortality from seafood-borne infections. We applied whole-genome sequencing and comparative analysis to investigate the evolution of this pathogen. The genome of biotype 1 strain, V. vulnificus YJ016, was sequenced and includes two chromosomes of estimated 3377 kbp and 1857 kbp in size, and a plasmid of 48,508 bp. A super-integron (SI) was identified, and the SI region spans 139 kbp and contains 188 gene cassettes. In contrast to non-SI sequences, the captured gene cassettes are unique for any given Vibrio species and are highly variable among V. vulnificus strains. Multiple rearrangements were found when comparing the 5.3-Mbp V. vulnificus YJ016 genome and the 4.0-Mbp V. cholerae El Tor N16961 genome. The organization of gene clusters of capsular polysaccharide, iron metabolism, and RTX toxin showed distinct genetic features of V. vulnificus and V. cholerae. The content of the V. vulnificus genome contained gene duplications and evidence of horizontal transfer, allowing for genetic diversity and function in the marine environment. The genomic information obtained in this study can be applied to monitoring vibrio infections and identifying virulence genes in V. vulnificus.

Amino Acid Sequence↗
PubMed2005

Identification of an aadA2 gene cassette from Salmonella enterica subsp. enterica Serovar derby.

During a study on Salmonella enterica subsp. enterica serovar Derby from slaughter-age pigs in Brazil, two epidemiologically unrelated multi-resistant S. Derby isolates were found to carry a class 1 integron with a single gene cassette. Sequence analysis confirmed that this gene cassette harboured an aadA2 gene. The aadA2 gene codes for an aminoglycoside adenyltransferase, which mediates resistance to the aminoglycoside streptomycin and the aminocyclitol spectinomycin. Although aadA2 gene cassettes are widely distributed among Salmonella, database searches identified an AadA2 protein indistinguishable from that of S. Derby only in single isolates of S. enterica subsp. enterica Enteritidis from France and S. enterica subsp. enterica Typhimurium from Japan. Structural analysis of the 59-base element revealed at least one base pair difference between the 59-base element of the aadA2 cassette from S. Derby and any of the 59-base elements deposited in the databases.

Abattoirs↗
PubMed2005

Isolation of an amikacin-resistant Escherichia coli strain after tobramycin treatment of previous recurrent episodes of respiratory tract infections caused by Pseudomonas aeruginosa.

Amikacin-resistant Escherichia coli strains are isolated rarely from clinical samples. In the present study, investigation of an amikacin-resistant clinical isolate of E. coli demonstrated the presence of two class 1 integrons carrying the aacA4 gene plus the aacA7 gene, and the dfrA17 gene plus the aadA5 gene, respectively. Resistance to amikacin in this E. coli isolate was related to the presence of both aacA4 and aacA7.

Amikacin↗
PubMed2005

The emergence and implications of metallo-beta-lactamases in Gram-negative bacteria.

The increase in Gram-negative broad-spectrum antibiotic resistance is worrisome, particularly as there are few, if any, ''pipeline'' antimicrobial agents possessing suitable activity against Pseudomonas spp. or Acinetobacter spp. The increase in resistance will be further enhanced by the acquisition of metallo-beta-lactamase (MBL) genes that can potentially confer broad-spectrum beta-lactam resistance. These genes encode enzymes that can hydrolyse all classes of beta-lactams and the activity of which cannot be neutralised by beta-lactamase inhibitors. MBL genes are often associated with aminoglycoside resistant genes and thus bacteria that possess MBL genes are often co-resistant to aminoglycosides, further compromising therapeutic regimes. Both types of genes can be found as gene cassettes carried by integrons that in turn are embedded within transposons providing a highly ambulatory genetic element. The dissemination of MBL genes is typified by the spread of blaVIM-2, believed to originate from a Portuguese patient in 1995, and is now present in over 20 counties. The increase in international travel is likely to be a contributory factor for the ascendancy of mobile MBL genes as much as the mobility among individual bacteria. Fitness, acquisition and host dependency are key areas that need to be addressed to enhance our understanding of how antibiotic resistance spreads. There is also a pressing need for new, and hopefully novel, compounds active against pan-resistant Gram-negative bacteria--a growing problem that needs to be addressed by both government and industry.

Aminoglycosides↗
PubMed2006

Genetic analysis of a multiresistant strain of Pseudomonas aeruginosa producing PER-1 beta-lactamase.

A multiresistant strain of Pseudomonas aeruginosa, PA2345, belonging to serotype O:1, was isolated at the Teaching Hospital of Besançon, France. Resistance to beta-lactams, including third-generation cephalosporins, depended upon a chromosomally-located composite transposon carrying the bla(PER-1) gene encoding extended-spectrum beta-lactamase PER-1. PA2345 was unrelated genotypically to two previous PER-1-producing isolates of P. aeruginosa. Sequence analysis of the transposon in PA2345 revealed the presence of two insertion sequences (ISPa23 and ISPa24) with very different predicted transposases (TnpA1, TnpA2), which were both bordered by closely related 16-bp inverted repeats. High resistance of PA2345 to aminoglycosides was caused, in part, by a chromosomal class-I integron containing gene cassettes aadB, encoding an ANT(2'') enzyme, and aadA11, encoding a new ANT(3'') enzyme with 281 amino-acids that conferred elevated resistance to streptomycin and spectinomycin. Stable overproduction of efflux system MexXY contributed to resistance to amikacin, while mutations in the quinolone resistance-determining regions of gyrA and parC accounted for the high resistance of PA2345 to fluoroquinolones. The study indicates that multidrug resistance in P. aeruginosa might arise from sequential acquisition of a variety of mechanisms provided by both horizontal gene transfers and mutations in chromosomal genes.

Drug Resistance, Multiple, Bacterial↗
PubMed2006

Septaplex PCR assay for rapid identification of Vibrio cholerae including detection of virulence and int SXT genes.

In this study, we describe a septaplex PCR assay for rapid identification of Vibrio cholerae including detection of the virulence and intsxt genes. Conditions were optimized to amplify fragments of ISRrRNA (encoding for 16S-23S rRNA gene, Intergenic spacer regions), O1rfb (O1 serogroup specific rfb), O139rfb (O139 serogroup specific rfb), ctxA (cholera toxin subunit A), tcpA (toxin coregulated pilus), and intsxt (sxt integron) simultaneously in a single PCR. The septaplex PCR was evaluated using 211 strains of V. cholerae and six water samples for in situ testing. PCR results were correlated with genotype data obtained by individual PCR and slot-blot assays. The one-step PCR described here can be used to identify V. cholerae accurately and rapidly. Also, the virulence and intsxt genes can be simultaneously detected, providing a useful method for monitoring pathogenic, intsxt-positive and nonpathogenic, intsxt-negative V. cholerae serogroups both in the environment and clinical settings.

Genes, Viral↗
PubMed2007

Molecular characterization of ICEVchVie0 and its disappearance in Vibrio cholerae O1 strains isolated in 2003 in Vietnam.

We analyzed 28 epidemic Vibrio cholerae O1 strains isolated in the region of Thua Thien Hue (Vietnam) in 2003. Ubiquitous amoxicillin, prevalent aminoglycosides and sporadic erythromycin resistances were observed. All were devoid of plasmids, class 1 integrons and ICEs and showed the same BglI ribotype, irrespective of their site of isolation and resistance pattern. A strain isolated in 1990 in the same area was resistant to amoxicillin and aminoglycosides but characterized by a different ribotype. This strain contained ICEVchVie0, belonging to the SXT/R391 ICE family, devoid of any resistance cluster. The molecular analysis of three conserved and six variable regions outlined an original genetic profile. ICEs not coding for resistance to drugs seem to be more frequent than supposed, and this finding reinforces the idea that the SXT/R391 family of genetic elements is wide and composite. The clearance of ICEVchVie0 in the 2003 epidemic may be explained by the lack of any resistance determinant as a favorable selective marker.

Aminoglycosides↗
PubMed2006

Genetic environment of acquired bla(ACC-1) beta-lactamase gene in Enterobacteriaceae isolates.

We studied the genetic organization of bla(ACC-1) in 14 isolates of Enterobacteriaceae from France, Tunisia, and Germany. In a common ancestor, ISEcp1 was likely involved in the mobilization of this gene from the Hafnia alvei chromosome to a plasmid. Other genetic events involving insertion sequences (particularly IS26), transposons (particularly Tn1696), or sulI-type integrons have occurred, leading to complex genetic environments.

Base Sequence↗
PubMed2007

First report of plasmid-mediated qnrA1 in a ciprofloxacin-resistant Escherichia coli strain in Latin America.

Among 144 ciprofloxacin-resistant Escherichia coli isolated in Brazil, one (0.69%) QnrA1-producing isolate was detected. The qnrA1 gene was associated with ISCR1. The QnrA1 determinant was carried on a 41-kb conjugative plasmid, which also carried a FOX-type cephalosporinase encoding gene and a class 1 integron with the aadB and catB3 cassettes. This is the first report of a qnrA-carrying isolate in a Latin American country.

Anti-Bacterial Agents↗
PubMed2005

Detection of qnr in clinical isolates of Escherichia coli from Korea.

qnr was detected in 2 of 260 Escherichia coli clinical isolates collected from a Korean hospital during the period 2001 to 2003. The two strains were not clonally related. qnr was located in In4 family class 1 integrons of original structure, downstream of orf513 and upstream from another resistance gene (dfrA3b) and a gene of unknown function (orf105). Transfer of the qnr determinant by conjugation could be detected from only one strain.

Anti-Infective Agents↗
PubMed2005

Multidrug-resistant Pseudomonas aeruginosa strain that caused an outbreak in a neurosurgery ward and its aac(6')-Iae gene cassette encoding a novel aminoglycoside acetyltransferase.

We characterized multidrug-resistant Pseudomonas aeruginosa strains isolated from patients involved in an outbreak of catheter-associated urinary tract infections that occurred in a neurosurgery ward of a hospital in Sendai, Japan. Pulsed-field gel electrophoresis of SpeI-, XbaI-, or HpaI-digested genomic DNAs from the isolates revealed that clonal expansion of a P. aeruginosa strain designated IMCJ2.S1 had occurred in the ward. This strain possessed broad-spectrum resistance to aminoglycosides, beta-lactams, fluoroquinolones, tetracyclines, sulfonamides, and chlorhexidine. Strain IMCJ2.S1 showed a level of resistance to some kinds of disinfectants similar to that of a control strain of P. aeruginosa, ATCC 27853. IMCJ2.S1 contained a novel class 1 integron, In113, in the chromosome but not on a plasmid. In113 contains an array of three gene cassettes of bla(IMP-1), a novel aminoglycoside resistance gene, and the aadA1 gene. The aminoglycoside resistance gene, designated aac(6')-Iae, encoded a 183-amino-acid protein that shared 57.1% identity with AAC(6')-Iq. Recombinant AAC(6')-Iae protein showed aminoglycoside 6'-N-acetyltransferase activity by thin-layer chromatography. Escherichia coli expressing exogenous aac(6')-Iae showed resistance to amikacin, dibekacin, isepamicin, kanamycin, netilmicin, sisomicin, and tobramycin but not to arbekacin, gentamicins, or streptomycin. Alterations of gyrA and parC at the amino acid sequence level were detected in IMCJ2.S1, suggesting that such mutations confer the resistance to fluoroquinolones observed for this strain. These results indicate that P. aeruginosa IMCJ2.S1 has developed multidrug resistance by acquiring resistance determinants, including a novel member of the aac(6')-I family and mutations in drug resistance genes.

Acetyltransferases↗
PubMed2006

Impact of antimicrobial usage on antimicrobial resistance in commensal Escherichia coli strains colonizing broiler chickens.

Escherichia coli strains isolated from commercial broilers and an experimental flock of chickens were screened to determine phenotypic expression of antimicrobial resistance and carriage of drug resistance determinants. The goal of this study was to investigate the influence of oxytetracycline, sarafloxacin, and enrofloxacin administration on the distribution of resistance determinants and strain types among intestinal commensal E. coli strains isolated from broiler chickens. We detected a high prevalence of resistance to drugs such as tetracycline (36 to 97%), sulfonamides (50 to 100%), and streptomycin (53 to 100%) in E. coli isolates from treated and untreated flocks. These isolates also had a high prevalence of class 1 integron carriage, and most of them possessed the streptomycin resistance cassette, aadA1. In order to investigate the contribution of E. coli strain distribution to the prevalence of antimicrobial resistance and the resistance determinants, isolates from each flock were DNA fingerprinted by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR. Although very diverse E. coli strain types were detected, four ERIC strain types were present on all of the commercial broiler farms, and two of the strains were also found in the experimental flocks. Each E. coli strain consisted of both susceptible and antimicrobial agent-resistant isolates. In some instances, isolates of the same E. coli strain expressed the same drug resistance patterns although they harbored different tet determinants or streptomycin resistance genes. Therefore, drug resistance patterns could not be explained solely by strain prevalence, indicating that mobile elements contributed significantly to the prevalence of resistance.

Animals↗
PubMed2006

Antimicrobial susceptibility and characterization of Salmonella isolates from processed bison carcasses.

Seventeen Salmonella enterica serovar Hadar isolates recovered from bison were found to possess a range of virulence genes and resistance to tetracycline, gentamicin, sulfamethoxazole, and streptomycin simultaneously. A 1-kb class 1 integron containing the aadA1 gene was identified in all isolates. Pulsed-field gel electrophoresis found that all isolates were closely related, indicating the possibility of cross-contamination during processing.

Animals↗
PubMed2006

Multiniche screening reveals the clinically relevant metallo-beta-lactamase VIM-2 in Pseudomonas aeruginosa far from the hospital setting: an ongoing dispersion process?

A screening study of the presence of metallo-beta-lactamases (IMP and VIM types and SPM-1) in isolates from different nonhospital sources was conducted, and it revealed the presence of bla(VIM-2), associated with the In58 class 1 integron, in two unrelated Pseudomonas aeruginosa strains from aquatic habitats. The results suggest that the hospital setting was the possible origin of these bla(VIM-2)-carrying strains.

Animals↗
PubMed2005

Exposure to rumen protozoa leads to enhancement of pathogenicity of and invasion by multiple-antibiotic-resistant Salmonella enterica bearing SGI1.

Multiple-antibiotic-resistant Salmonella enterica serotype Typhimurium is a food-borne pathogen that has been purported to be more virulent than antibiotic-sensitive counterparts. The paradigm for this multiresistant/hyperpathogenic phenotype is Salmonella enterica serotype Typhimurium phage type DT104 (DT104). The basis for the multiresistance in DT104 is related to an integron structure designated SGI1, but factors underlying hyperpathogenicity have not been completely identified. Since protozoa have been implicated in the alteration of virulence in Legionella and Mycobacterium spp., we attempted to assess the possibility that protozoa may contribute to the putative hypervirulence of DT104. Our study reveals that DT104 can be more invasive, as determined by a tissue culture invasion assay, after surviving within protozoa originating from the bovine rumen. The enhancement of invasion was correlated with hypervirulence in a bovine infection model in which we observed a more rapid progression of disease and a greater recovery rate for the pathogen. Fewer DT104 cells were recovered from tissues of infected animals when protozoa were lysed by preinfection chemical defaunation of the bovine or ovine rumen. The protozoan-mediated hypervirulence phenotype was observed only in DT104 and other Salmonella strains, including serovars Agona and Infantis, possessing SGI1.

Animals↗