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827 records · Page 46Linked to original sources
PubMed2006

Molecular epidemiology of VIM-4 metallo-beta-lactamase-producing Pseudomonas sp. isolates in Hungary.

VIM metallo-beta-lactamase-producing serotype O11 or O12 Pseudomonas aeruginosa isolates infecting or colonizing 19 patients from seven hospitals in Hungary were characterized between October 2003 and November 2005. Macrorestriction analysis revealed the involvement of hospitals from three different towns in northwest Hungary in an outbreak caused by VIM-4-producing P. aeruginosa.

Base Sequence↗
PubMed2006

Common region CR1 for expression of antibiotic resistance genes.

The CR1 element defined by an orf513 gene encoding a putative recombinase and a recombination crossover site has been identified upstream of several antibiotic resistance genes in Enterobacteriaceae. This CR1 element was shown to bring promoter sequences that play a role in the expression of unrelated antibiotic resistance genes.

Anti-Bacterial Agents↗
PubMed2004

Tetracycline and streptomycin resistance genes, transposons, and plasmids in Salmonella enterica isolates from animals in Italy.

Fifty-eight multidrug-resistant Salmonella enterica strains of 20 serotypes, isolated from animal sources in Italy, were analyzed for tet(A) and strA-strB, conferring tetracycline and streptomycin resistance, respectively. The strA and strB genes were highly prevalent in Salmonella strains of our collection, being detected in 84% of the streptomycin-resistant strains. In many strains, the strA and strB genes were linked to a particular Tn5393-derivative transposon characterized by the presence of the insertion sequence IS1133, previously identified only in the plant pathogen Erwinia amylovora. Sixty-eight percent of the tetracycline-resistant strains were tet(A) positive, indicating that this gene is widely diffused in Salmonella strains circulating in animals in Italy. Most of the tet(A) genes were localized within a deleted Tn1721 transposon variant. Two prevalent repN and repI1 resistance plasmids were identified in Salmonella isolates of our collection.

Animals↗
PubMed2005

Genetic environment and expression of the extended-spectrum beta-lactamase blaPER-1 gene in gram-negative bacteria.

The genetic location of the gene coding for the expanded-spectrum beta-lactamase PER-1 was analyzed in a series of gram-negative isolates. It was identified as part of a composite transposon bracketed by two novel insertion elements, ISPa12 and ISPa13, belonging to the IS4 family that possess transposases that share 63% amino acid identity and that are chromosomally located in Pseudomonas aeruginosa, Providencia stuartii, and Acinetobacter baumannii. On the contrary, the bla(PER-1) gene was identified just downstream of an ISPa12 element but not within a composite transposon when it was located on a plasmid in Salmonella enterica serovar Typhimurium and A. baumannii isolates. In both cases, expression of the bla(PER-1) gene was driven by promoter sequences located in ISPa12.

Base Sequence↗
PubMed2006

SXT-related integrating conjugative element in New World Vibrio cholerae.

SXT-related integrating conjugative elements (ICEs) became prevalent in Asian Vibrio cholerae populations after V. cholerae O139 emerged. Here, we describe an SXT-related ICE, ICEVchMex1, in a Mexican environmental V. cholerae isolate. Identification of ICEVchMex1 represents the first description of an SXT-related ICE in the Western Hemisphere. The significant differences between the SXT and ICEVchMex1 genomes suggest that these ICEs have evolved independently.

Conjugation, Genetic↗
PubMed2007

Modes and modulations of antibiotic resistance gene expression.

Since antibiotic resistance usually affords a gain of function, there is an associated biological cost resulting in a loss of fitness of the bacterial host. Considering that antibiotic resistance is most often only transiently advantageous to bacteria, an efficient and elegant way for them to escape the lethal action of drugs is the alteration of resistance gene expression. It appears that expression of bacterial resistance to antibiotics is frequently regulated, which indicates that modulation of gene expression probably reflects a good compromise between energy saving and adjustment to a rapidly evolving environment. Modulation of gene expression can occur at the transcriptional or translational level following mutations or the movement of mobile genetic elements and may involve induction by the antibiotic. In the latter case, the antibiotic can have a triple activity: as an antibacterial agent, as an inducer of resistance to itself, and as an inducer of the dissemination of resistance determinants. We will review certain mechanisms, all reversible, that bacteria have elaborated to achieve antibiotic resistance by the fine-tuning of the expression of genetic information.

Bacteria↗
PubMed2005

Clonal diversity of metallo-beta-lactamase-possessing Pseudomonas aeruginosa in geographically diverse regions of Japan.

The aim of this study was to determine the distribution of metallo-beta-lactamase-producing Pseudomonas aeruginosa in Japan and to investigate the molecular characteristics of resistance gene cassettes including the gene encoding this enzyme. A total of 594 nonduplicate strains of P. aeruginosa isolated from 60 hospitals throughout Japan in 2002 were evaluated. This study indicated that although the prevalence of imipenem-resistant P. aeruginosa has not increased compared to that found in previous studies, clonal distribution of the same strain across Japan is evident.

Anti-Bacterial Agents↗
PubMed2006

ISCR elements: novel gene-capturing systems of the 21st century?

"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-beta-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.

Aminoglycosides↗
PubMed2005

Antibiotic resistance in the intensive care unit: a primer in bacteriology.

The clinical use of potent, well-tolerated, broad-spectrum antibiotics has been paralleled by the development of resistance in bacteria, and the prevalence of highly resistant bacteria in some intensive care units is despairingly commonplace. The intensive care community faces the realistic prospect of untreatable nosocomial infections and should be searching for new approaches to diagnose and manage resistant bacteria. In this review, we discuss some of the relevant underlying biology, with a particular focus on genetic transfer vehicles and the relationship of selection pressure to their movements. It is an attempt to demystify the relevant language and concepts for the anaesthetist and intensivist, to explain some of the reasons for the emergence of resistance in bacteria, and to provide a contextual basis for discussion of management approaches such as selective decontamination and antibiotic cycling.

Bacteriophages↗
PubMed2006

Comparative integromics on Ephrin family.

EFNA1, EFNA2, EFNA3, EFNA4, EFNA5, EFNB1, EFNB2 and EFNB3 are EFN family ligands for EPH family receptors. EFN/EPH signaling pathway networks with the WNT signaling pathway during embryogenesis, tissue regeneration, and carcinogenesis. Comparative genomics analyses on EFNB1, EFNB2 and EFNB3 were performed by using bioinformatics and human intelligence (humint). EFNB1 mRNA was expressed in human embryonic stem (ES) cells, neural tissues, diffuse type gastric cancer, pancreatic cancer, colon cancer, brain tumors and esophageal cancer, EFNB2 mRNA in human ES cells, neural tissues and colon cancer, EFNB3 mRNA in human ES cells, neural tissues, brain tumors, pancreatic cancer and colon cancer. Because triple TCF/LEF-binding sites were identified within the 5'-promoter region of human EFNB3 gene, comparative genomics analyses on EFNB3 orthologs were further performed. Chimpanzee EFNB3 gene, consisting of five exons, was identified within AC164921.3 genome sequence. AY421228.1 was not a correct coding sequence for chimpanzee EFNB3. Chimpanzee EFNB3 gene was found to encode a 340-amino-acid protein showing 99.4% and 96.6% total-amino-acid identity with human EFNB3 and mouse Efnb3, respectively. Three TCF/LEF-binding sites within human EFNB3 promoter were conserved in chimpanzee EFNB3 promoter, and the second TCF/LEF-binding site in rodent Efnb3 promoters. CpG hypermethylation of EFNB3 promoter with 63.2% GC content as well as deletion of EFNB3 gene closely linked to TP53 tumor suppressor gene at human chromosome 17p13.1 should be investigated to elucidate the mechanism of infrequent EFNB3 upregulation in human colorectal cancer. EFNB3, identified as potential transcriptional target of WNT/beta-catenin signaling pathway, is a pharmacogenomics target in the fields of regenerative medicine and oncology.

Amino Acid Sequence↗
PubMed2006

Comparative integromics on Eph family.

EPHA1, EPHA2, EPHA3, EPHA4, EPHA5, EPHA6, EPHA7, EPHA8, EPHA10, EPHB1, EPHB2, EPHB3, EPHB4 and EPHB6 are EPH family receptors for Ephrin family ligands. Ephrin/EPH signaling pathway networks with the WNT signaling pathway during embryogenesis, tissue regeneration, and carcinogenesis. TCF/LEF-binding sites within the promoter region of human EPH family members were searched for by using bioinformatics and human intelligence. Because five TCF/LEF-binding sites were identified within the 5'-promoter region of the EPHA7 gene, comparative genomics analyses on EPHA7 orthologs were further performed. EPHA7-MANEA-FHL5 locus at human chromosome 6q16.1 and EPHA10-MANEAL-FHL3 locus at human chromosome 1p34.3 were paralogous regions within the human genome. Human EPHA7 mRNA was expressed in embryonic stem (ES) cells, neural tissues, duodenal cancer and parathyroid tumors, while mouse Epha7 mRNA was expressed in fertilized egg, Rathke's pouche, visual cortex, pituitary gland, other neural tissues, pancreas, lung tumors and mammary tumors. The chimpanzee EPHA7 gene and cow Epha7 gene were identified within NW_107969.1 and AC155055.2 genome sequences, respectively. Five TCF/LEF-binding sites within human EPHA7 promoter were conserved in the chimpanzee EPHA7 promoter, and three TCF/LEF-binding sites in the cow Epha7 promoter, but none in the mouse Epha7 promoter. Primates and cow EPHA7 orthologs were identified as evolutionarily conserved targets of the WNT/beta-catenin signaling pathway. D6S1056 microsatellite marker within EPHA7 gene is deleted in prostate cancer. Deletion and/or promoter CpG hypermethylation could explain the EPHA7 down-regulation in human tumors. EPHA7 is a target of systems medicine, especially in the fields of regenerative medicine and oncology.

Animals↗
PubMed2006

Dissemination of Salmonella enterica serotype agona and multidrug-resistant Salmonella enterica serotype typhimurium in Cuba.

The molecular epidemiology, antimicrobial susceptibility, and mechanisms of resistance of 34 Salmonella spp. strains causing acute gastroenteritis, isolated from different provinces in Cuba, were determined. Sixty-four percent of the strains showed multiresistance. Salmonella typhimurium was the most frequent with 15 strains (44%), 13 of which belonged to phagotype 104 and presented similar genetic profiles of pulsed field gel electrophoresis. High levels of resistance to tetracycline (53%), spectinomycin (50%), ampicillin (44%), and chloramphenicol (41%) were found. Resistance to tetracycline was associated with the tet G and tet A genes. Resistance to ampicillin was caused by the presence of beta-lactamases, mainly the CARB type. The floR gene was the main mechanism of resistance to chloramphenicol. Our results showed an antimicrobial susceptible clone of Salmonella enterica serotype Agona in two separate regions. This is the first report of the widespread dissemination of a multiresistant clone of S. enterica serotype Typhimurium definitive phage type 104 in Cuba.

Anti-Bacterial Agents↗