# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 482 | 0 | 1.0000 | Natural hot spots for gain of multiple resistances: arsenic and antibiotic resistances in heterotrophic, aerobic bacteria from marine hydrothermal vent fields. Microorganisms are responsible for multiple antibiotic resistances that have been associated with resistance/tolerance to heavy metals, with consequences to public health. Many genes conferring these resistances are located on mobile genetic elements, easily exchanged among phylogenetically distant bacteria. The objective of the present work was to isolate arsenic-, antimonite-, and antibiotic-resistant strains and to determine the existence of plasmids harboring antibiotic/arsenic/antimonite resistance traits in phenotypically resistant strains, in a nonanthropogenically impacted environment. The hydrothermal Lucky Strike field in the Azores archipelago (North Atlantic, between 11°N and 38°N), at the Mid-Atlantic Ridge, protected under the OSPAR Convention, was sampled as a metal-rich pristine environment. A total of 35 strains from 8 different species were isolated in the presence of arsenate, arsenite, and antimonite. ACR3 and arsB genes were amplified from the sediment's total DNA, and 4 isolates also carried ACR3 genes. Phenotypic multiple resistances were found in all strains, and 7 strains had recoverable plasmids. Purified plasmids were sequenced by Illumina and assembled by EDENA V3, and contig annotation was performed using the "Rapid Annotation using the Subsystems Technology" server. Determinants of resistance to copper, zinc, cadmium, cobalt, and chromium as well as to the antibiotics β-lactams and fluoroquinolones were found in the 3 sequenced plasmids. Genes coding for heavy metal resistance and antibiotic resistance in the same mobile element were found, suggesting the possibility of horizontal gene transfer and distribution of theses resistances in the bacterial population. | 2015 | 25636836 |
| 486 | 1 | 0.9997 | Detection of heavy metal ion resistance genes in gram-positive and gram-negative bacteria isolated from a lead-contaminated site. Resistance to a range of heavy metal ions was determined for lead-resistant and other bacteria which had been isolated from a battery-manufacturing site contaminated with high concentration of lead. Several Gram-positive (belonging to the genera Arthrobacter and Corynebacterium) and Gram-negative (Alcaligenes species) isolates were resistant to lead, mercury, cadmium, cobalt, zinc and copper, although the levels of resistance to the different metal ions were specific for each isolate. Polymerase chain reaction, DNA-DNA hybridization and DNA sequencing were used to explore the nature of genetic systems responsible for the metal resistance in eight of the isolates. Specific DNA sequences could be amplified from the genomic DNA of all the isolates using primers for sections of the mer (mercury resistance determinant on the transposon Tn501) and pco (copper resistance determinant on the plasmid pRJ1004) genetic systems. Positive hybridizations with mer and pco probes indicated that the amplified segments were highly homologous to these genes. Some of the PCR products were cloned and partially sequenced, and the regions sequenced were highly homologous to the appropriate regions of the mer and pco determinants. These results demonstrate the wide distribution of mercury and copper resistance genes in both Gram-positive and Gram-negative isolates obtained from this lead-contaminated soil. In contrast, the czc (cobalt, zinc and cadmium resistance) and chr (chromate resistance) genes could not be amplified from DNAs of some isolates, indicating the limited contribution, if any, of these genetic systems to the metal ion resistance of these isolates. | 1997 | 9342884 |
| 3701 | 2 | 0.9996 | Genetic Determinants for Metal Tolerance and Antimicrobial Resistance Detected in Bacteria Isolated from Soils of Olive Tree Farms. Copper-derived compounds are often used in olive tree farms. In a previous study, a collection of bacterial strains isolated from olive tree farms were identified and tested for phenotypic antimicrobial resistance and heavy metal tolerance. The aim of this work was to study the genetic determinants of resistance and to evaluate the co-occurrence of metal tolerance and antibiotic resistance genes. Both metal tolerance and antibiotic resistance genes (including beta-lactamase genes) were detected in the bacterial strains from Cu-treated soils. A high percentage of the strains positive for metal tolerance genes also carried antibiotic resistance genes, especially for genes involved in resistances to beta-lactams and tetracycline. Significant associations were detected between genes involved in copper tolerance and genes coding for beta-lactamases or tetracycline resistance mechanisms. A significant association was also detected between zntA (coding for a Zn(II)-translocating P-type ATPase) and tetC genes. In conclusion, bacteria from soils of Cu-treated olive farms may carry both metal tolerance and antibiotic resistance genes. The positive associations detected between metal tolerance genes and antibiotic resistance genes suggests co-selection of such genetic traits by exposure to metals. | 2020 | 32756388 |
| 3601 | 3 | 0.9996 | R factors mediate resistance to mercury, nickel, and cobalt. Fifty-five clinical isolates and laboratory stocks of Escherichia coli and Salmonella were studied for resistance to each of ten metals. Eleven clinical isolates carrying R factors were resistant to mercury, and, in each case, the resistance was mediated by a previously undefined R-factor gene. The gene was phenotypically expressed within 2 to 4 minutes after entry into sensitive bacteria, but the basis for the resistance remains undefined. Fourteen strains, 12 infected with R factors, were resistant to cobalt and nickel, but these resistances were mediated by R-factor genes in only two strains; separate R-factor genes mediated the resistances to nickel and cobalt. These and other results indicate that the genetic composition of R factors is greater than that originally defined. | 1967 | 5337360 |
| 2833 | 4 | 0.9996 | Heavy metal resistance genes and plasmid-mediated quinolone resistance genes in Arthrobacter sp. isolated from Brazilian soils. Arthrobacter sp. are Gram-positive bacilli commonly obtained from soil and in the hospital environment. These species have been reported to cause several types of infection. Heavy metals are a threat to the ecological system due to their high-levels of toxicity and the fluoroquinolones are antimicrobials widely used for the treatment of different bacterial infections. The aim of this study was to investigate the resistance to fluoroquinolone and heavy metals, the presence of plasmid-mediated resistance (PMQR) genes and heavy metals resistance (HMR) genes and the presence of plasmids in Arthrobacter sp. obtained from Brazilian soils. Bacterial isolation was performed using soil samples from different Brazilian regions. The bacterial identification was performed by 16S rRNA gene sequencing. The resistance profile for fluoroquinolones and heavy metals was determined by MIC. Several PMQR and HMR genes and plasmid families were investigated by PCR. Eight isolates were obtained from soil samples from different cultivations and regions of Brazil. All isolates were resistant to all fluoroquinolones, cadmium, cobalt and zinc and the majority to copper. Among the PMQR genes, the qepA (4) was the most prevalent, followed by qnrS (3), qnrB (3), oqxB (2) and oqxA (1). Among the HMR genes, the copA was detected in all isolates and the czcA in two isolates. The replication origin of the ColE-like plasmid was detected in all isolates; however, no plasmid was detected by extraction. The association of resistance to heavy metals and antimicrobials is a threat to the environmental balance and to human health. There are no studies reporting the association of PMQR and HMR genes in bacteria belonging to the genus Arthrobacter. To the best of our knowledge, this is the first report of qnrB, qepA, oqxA and oqxB in Arthrobacter species. | 2019 | 31129890 |
| 3356 | 5 | 0.9996 | Conjugative multiple-antibiotic resistance plasmids in Escherichia coli isolated from environmental waters contaminated by human faecal wastes. AIMS: To better understand the involvement of faecal contamination in the dissemination of antibiotic resistance genes, we investigated the genetic supports of resistances in nine multi-resistant Escherichia coli strains originating from human faecal contamination, and isolated from three different aquatic environments used for producing drinking water. METHODS AND RESULTS: Seven strains harboured at least one large plasmid that we have characterized (size, antibiotic resistance patterns, incompatibility group, capacity of autotransfer, presence of integron). Most of these plasmids were conjugative and carried numerous resistances. One of the plasmids studied, belonging to the IncP incompatibility group, was able to transfer by conjugation to Pseudomonas fluorescens and Aeromonas sp. Only two of the plasmids we studied carried class 1 and/or 2 integron(s). CONCLUSIONS: Conjugative plasmids isolated from multi-resistant E. coli strains explained most of the resistances of their host strains and probably contribute to the spread of antibiotic resistance genes coming from human faecal contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: These results highlight the key role played by plasmids in the multi-resistance phenotype of faecal bacteria and the diversity of these genetic structures. Contaminated water, especially accidentally contaminated drinking water, could be a path back to humans for these plasmids. | 2015 | 25387599 |
| 6156 | 6 | 0.9996 | Diversity of arsenite transporter genes from arsenic-resistant soil bacteria. A PCR approach was developed to assess the occurrence and diversity of arsenite transporters in arsenic-resistant bacteria. For this purpose, three sets of degenerate primers were designed for the specific amplification of approximately 750bp fragments from arsB and two subsets of ACR3 (designated ACR3(1) and ACR3(2)) arsenite carrier gene families. These primers were used to screen a collection of 41 arsenic-resistant strains isolated from two soil samples with contrasting amounts of arsenic. PCR results showed that 70.7% of the isolates contained a gene related to arsB or ACR3, with three of them carrying both arsB and ACR3-like genes. Phylogenetic analysis of the protein sequences deduced from the amplicons indicated a prevalence of arsB in Firmicutes and Gammaproteobacteria, while ACR3(1) and ACR3(2) were mostly present in Actinobacteria and Alphaproteobacteria, respectively. In addition to validating the use of degenerate primers for the identification of arsenite transporter genes in a taxonomically wide range of bacteria, the study describes a novel collection of strains displaying interesting features of resistance to arsenate, arsenite and antimonite, and the ability to oxidize arsenite. | 2007 | 17258434 |
| 4529 | 7 | 0.9996 | Evolution of gentamicin and arsenite resistance acquisition in Ralstonia pickettii water isolates. Ralstonia pickettii are ubiquitous in water environments. Members of this species are frequently, but not always, resistant to both gentamicin and arsenite. Gentamicin and arsenite co-resistance and the putative molecular mechanisms were investigated. A group of 37 R. pickettii strains isolated from drinking water and hospital wastewater were characterized for gentamicin and arsenite resistance phenotypes, the number and size of plasmids, and screened for genetic elements associated with arsenite tolerance, Integrative and Conjugative Elements (ICEs), among other. The genomes of three representative strains were compared. Most gentamicin resistant (GR) isolates (32/33) were resistant to arsenite, and harbored ICE- and ars operon-related genes. These genetic elements were not detected in any of the five arsenite susceptible strains, regardless of the GR (n = 1) or gentamicin susceptibility (GS) (n = 4) phenotype. The comparison of the genomes of two GR (one resistant and one susceptible to arsenite) and one GS strains suggested that these phenotypes correspond to three phylogroups, distinguished by presence of some genes only in GR isolates, in addition to point mutations in functional genes. The presence of ICEs and ars operon-related genes suggest that arsenite resistance might have been acquired by GR lineages. | 2021 | 33197514 |
| 4662 | 8 | 0.9996 | Characterization of a multiresistant mosaic plasmid from a fish farm Sediment Exiguobacterium sp. isolate reveals aggregation of functional clinic-associated antibiotic resistance genes. The genus Exiguobacterium can adapt readily to, and survive in, diverse environments. Our study demonstrated that Exiguobacterium sp. strain S3-2, isolated from marine sediment, is resistant to five antibiotics. The plasmid pMC1 in this strain carries seven putative resistance genes. We functionally characterized these resistance genes in Escherichia coli, and genes encoding dihydrofolate reductase and macrolide phosphotransferase were considered novel resistance genes based on their low similarities to known resistance genes. The plasmid G+C content distribution was highly heterogeneous. Only the G+C content of one block, which shared significant similarity with a plasmid from Exiguobacterium arabatum, fit well with the mean G+C content of the host. The remainder of the plasmid was composed of mobile elements with a markedly lower G+C ratio than the host. Interestingly, five mobile elements located on pMC1 showed significant similarities to sequences found in pathogens. Our data provided an example of the link between resistance genes in strains from the environment and the clinic and revealed the aggregation of antibiotic resistance genes in bacteria isolated from fish farms. | 2014 | 24362420 |
| 483 | 9 | 0.9996 | Present-day mercury resistance transposons are common in bacteria preserved in permafrost grounds since the Upper Pleistocene. Transposons closely related to mercury resistance transposons Tn5041, Tn5053, and Tn5056, which have been previously described in present-day bacteria, were detected in a survey of 12 mercury-resistant Pseudomonas strains isolated from permafrost samples aged 15-40 thousand years. In addition, Tn5042, a novel type of mercury resistance transposon, was revealed in the permafrost strain collection and its variants found to be common among present-day bacteria. The results reveal that no drastic changes in the distribution mode of the different types of mercury resistance transposons among environmental bacteria have taken place in the last 15-40 thousand years. | 2005 | 16084067 |
| 2803 | 10 | 0.9996 | Antimicrobial resistance, heavy metal resistance and integron content in bacteria isolated from a South African tilapia aquaculture system. Antibacterial compounds and metals co-select for antimicrobial resistance when bacteria harbour resistance genes towards both types of compounds, facilitating the proliferation and evolution of antimicrobial and heavy metal resistance. Antimicrobial and heavy metal resistance indices of 42 Gram-negative bacteria from a tilapia aquaculture system were determined to identify possible correlations between these phenotypes. Agar dilution assays were carried out to determine susceptibility to cadmium, copper, lead, mercury, chromate and zinc, while susceptibility to 21 antimicrobial agents was investigated by disk diffusion assays. Presence of merA, the mercury resistance gene, was determined by dot-blot hybridizations and PCR. Association of mercury resistance with integrons and transposon Tn21 was also investigated by PCR. Isolates displayed a high frequency of antimicrobial (erythromycin: 100%; ampicillin: 85%; trimethoprim: 78%) and heavy metal (Zn2+: 95%; Cd2+: 91%) resistance. No correlation was established between heavy metal and multiple antibiotic resistance indices. Significant positive correlations were observed between heavy metal resistance profiles, indices, Cu2+ and Cr3+ resistance with erythromycin resistance. Significant positive correlations were observed between merA (24%)/Tn21 (24%) presence and heavy metal resistance profiles and indices; however, significant negative correlations were obtained between integron-associated qacE∆1 (43%) and sulI (26%) gene presence and heavy metal resistance indices. Heavy metal and antimicrobial agents co-select for resistance, with fish-associated, resistant bacteria demonstrating simultaneous heavy metal resistance. Thus, care should be taken when using anti-fouling heavy metals as feed additives in aquaculture facilities. | 2017 | 29160218 |
| 3360 | 11 | 0.9996 | Gentamicin resistance genes in environmental bacteria: prevalence and transfer. A comprehensive multiphasic survey of the prevalence and transfer of gentamicin resistance (Gm(r)) genes in different non-clinical environments has been performed. We were interested to find out whether Gm(r) genes described from clinical isolates can be detected in different environmental habitats and whether hot spots can be identified. Furthermore, this study aimed to evaluate the impact of selective pressure on the abundance and mobility of resistance genes. The study included samples from soils, rhizospheres, piggery manure, faeces from cattle, laying and broiler chickens, municipal and hospital sewage water, and coastal water. Six clusters of genes coding for Gm-modifying enzymes (aac(3)-I, aac(3)-II/VI, aac(3)-III/IV, aac(6')-II/Ib, ant(2'')-I, aph(2'')-I) were identified based on a database comparison and primer systems for each gene cluster were developed. Gm-resistant bacteria isolated from the different environments had a different taxonomic composition. In only 34 of 207 isolates, mainly originating from sewage, faeces and coastal water polluted with wastewater, were known Gm(r) genes corresponding to five of the six clusters detected. The strains belonged to genera in which the genes had previously been detected (Enterobacteriaceae, Pseudomonas, Acinetobacter) but also to phylogenetically distant bacteria, such as members of the CFB group, alpha- and beta-Proteobacteria. Gm(r) genes located on mobile genetic elements (MGE) could be captured in exogenous isolations into recipients belonging to alpha-, beta- and gamma-Proteobacteria from all environments except for soil. A high proportion of the MGE, conferring Gm resistance isolated from sewage, were identified as IncPbeta plasmids. Molecular detection of Gm(r) genes, and broad host range plasmid-specific sequences (IncP-1, IncN, IncW and IncQ) in environmental DNA indicated a habitat-specific dissemination. A high abundance and diversity of Gm(r) genes could be shown for samples from faeces (broilers, layers, cattle), from sewage, from seawater, collected close to a wastewater outflow, and from piggery manure. In the latter samples all six clusters of Gm(r) genes could be detected. The different kinds of selective pressure studied here seemed to enhance the abundance of MGE, while an effect on Gm(r) genes was not obvious. | 2002 | 19709289 |
| 4970 | 12 | 0.9996 | Massive analysis of 64,628 bacterial genomes to decipher water reservoir and origin of mobile colistin resistance genes: is there another role for these enzymes? Since 2015, new worrying colistin resistance mechanism, mediated by mcr-1 gene has been reported worldwide along with eight newly described variants but their source(s) and reservoir(s) remain largely unexplored. Here, we conducted a massive bioinformatic analysis of bacterial genomes to investigate the reservoir and origin of mcr variants. We identified 13'658 MCR-1 homologous sequences in 494 bacterial genera. Moreover, analysis of 64'628 bacterial genomes (60 bacterial genera and 1'047 species) allows identifying a total of 6'651 significant positive hits (coverage >90% and similarity >50%) with the nine MCR variants from 39 bacterial genera and more than 1'050 species. A high number of MCR-1 was identified in Escherichia coli (n = 862). Interestingly, while almost all variants were identified in bacteria from different sources (i.e. human, animal, and environment), the last variant, MCR-9, was exclusively detected in bacteria from human. Although these variants could be identified in bacteria from human and animal sources, we found plenty MCR variants in unsuspected bacteria from environmental origin, especially from water sources. The ubiquitous presence of mcr variants in bacteria from water likely suggests another role in the biosphere of these enzymes as an unknown defense system against natural antimicrobial peptides and/or bacteriophage predation. | 2020 | 32249837 |
| 1972 | 13 | 0.9996 | Draft Genome Sequences of Multidrug-Resistant Escherichia coli Isolated from River Water. The spread of antibiotic resistance poses a critical challenge worldwide. Contaminated environments can become reservoirs, spreading antibiotic-resistant bacteria and genetic determinants of resistance to humans directly or indirectly. Here, we report the draft genome sequence, the resistome, virulence genes, and sequence types of seven multidrug-resistant Escherichia coli strains isolated from river water. | 2022 | 36222705 |
| 4953 | 14 | 0.9996 | MCR-5-Producing Colistin-Resistant Cupriavidus gilardii Strain from Well Water in Batna, Algeria. This paper presents the first description of the mcr-5.1 gene in a colistin-resistant Cupriavidus gilardii isolate from well water that supplies a maternity hospital in Algeria. The whole-genome sequence of this strain showed the presence of putative β-lactamase, aac(3)-IVa, and multidrug efflux pump-encoding genes, which could explain the observed multidrug resistance phenotype. Our findings are of great interest, as we highlight a potential contamination route for the spread of mcr genes. IMPORTANCE Colistin resistance mediated by mcr genes in Gram-negative bacteria has gained significant attention worldwide. This is due to the ability of these genes to be horizontally transferred between different bacterial genera and species. Aquatic environments have been suggested to play an important role in the emergence and spread of this resistance mechanism. Here, we describe the first report of an mcr-5-positive Cupriavidus gilardii aquatic isolate through its isolation from well water in Algeria. The significance of our study is in shedding the light on an important environmental reservoir of mcr genes. | 2021 | 34468167 |
| 4971 | 15 | 0.9996 | Antimicrobial and Metal Resistance Genes in Bacteria Isolated from Mine Water in Austria. Background/Objectives: Microbiomes surrounding mining sites have been found to harbor both antibiotic resistance genes and metal resistance genes. Within the "One Health" framework, which spans human, veterinary and environmental health, it is crucial to determine whether bacterial metal resistance (MR) genes can independently trigger antimicrobial resistance (AMR) or if they are linked to AMR genes and co-transferred horizontally. Methods and Results: Bacteria were isolated from an active and an inactive mining site in the alpine region of Austria. Most of the isolated bacteria harbored antimicrobial and metal resistance genes (88%). MALDI-TOF and whole genome sequencing (WGS) revealed that species from the Pseudomonadaceae family were the most identified, accounting for 32.5%. All Pseudomonas spp. carried AMR genes from the mex family, which encode multidrug efflux pumps. β-lactamase production encoded by bla genes were detected as the second most common (26%). The same AMR genes have often been detected within a particular bacterial genus. No tetracycline resistance gene has been identified. Among metal resistance genes, rufB (tellurium resistance) was the most prevalent (33%), followed by recGM (selenium resistance, 30%), copA (copper resistance, 26%), and mgtA (magnesium and cobalt resistance, 26%). Notably, the mer gene family (mercury resistance) was found exclusively in isolates from the inactive mining site (n = 6). In addition, genes associated with both antimicrobial and metal resistance, including arsBM, acrD, and the mer operon, were identified in 19 out of the 43 isolates. Conclusions: Bacteria isolated from mine water harbored both MR and AMR genes. Given the exceptional diversity of bacterial species in these settings, 16S rRNA gene sequence analysis is the recommended method for accurate species identification. Moreover, the presence of multi-drug transporters and transferable resistance genes against critically important antimicrobials such as fluoroquinolones and colistin identified in these environmental bacteria emphasizes the importance of retrieving environmental data within the "One Health" framework. | 2025 | 40149073 |
| 4973 | 16 | 0.9996 | Plasmidome analysis of a hospital effluent biofilm: Status of antibiotic resistance. Plasmids are widely involved in the dissemination of characteristics within bacterial communities. Their genomic content can be assessed by high-throughput sequencing of the whole plasmid fraction of an environment, the plasmidome. In this study, we analyzed the plasmidome of a biofilm formed in the effluents of the teaching hospital of Clermont-Ferrand (France). Our analysis discovered >350 new complete plasmids, with a length ranging from 1219 to 40,193 bp. Forty-two plasmid incompatibility (Inc) groups were found among all the plasmid contigs. Ten large plasmids, described here in detail, were reconstructed from plasmid contigs, seven of which carried antibiotic resistance genes. Four plasmids potentially confer resistance to numerous families of antibiotics, including carbapenems, aminoglycosides, colistin, and chloramphenicol. Most of these plasmids were affiliated to Proteobacteria, a phylum of Gram-negative bacteria. This study therefore illustrates the composition of an environmental mixed biofilm in terms of plasmids and antibiotic resistance genes. | 2022 | 35691511 |
| 3359 | 17 | 0.9996 | Marine bacteria harbor the sulfonamide resistance gene sul4 without mobile genetic elements. Marine bacteria are possible reservoirs of antibiotic-resistance genes (ARGs) originating not only from clinical and terrestrial hot spots but also from the marine environment. We report here for the first time a higher rate of the sulfonamide-resistance gene sul4 in marine bacterial isolates compared with other sul genes. Among four sulfonamide-resistance genes (sul1, sul2, sul3, and sul4), sul4 was most abundant (45%) in 74 sulfonamide-resistant marine isolates by PCR screening. The order of abundance was sul4 (33 isolates) >sul2 (6 isolates) >sul3 (5 isolates) >sul1 (1 isolate). Whole-genome sequencing of 23 isolates of sul4-expressing α- and γ-proteobacteria and bacilli revealed that sul4 was not accompanied by known mobile genetic elements. This suggests that sul4 in these marine isolates is clonally transferred and not horizontally transferable. Folate metabolism genes formed a cluster with sul4, suggesting that the cluster area plays a role in folate metabolism, at which sul4 functions as a dihydropteroate synthase. Thus, sul4 might be expressed in marine species and function in folate synthesis, but it is not a transferable ARG. | 2023 | 37779713 |
| 3600 | 18 | 0.9995 | Uncultured soil bacteria are a reservoir of new antibiotic resistance genes. Antibiotic resistance genes are typically isolated by cloning from cultured bacteria or by polymerase chain reaction (PCR) amplification from environmental samples. These methods do not access the potential reservoir of undiscovered antibiotic resistance genes harboured by soil bacteria because most soil bacteria are not cultured readily, and PCR detection of antibiotic resistance genes depends on primers that are based on known genes. To explore this reservoir, we isolated DNA directly from soil samples, cloned the DNA and selected for clones that expressed antibiotic resistance in Escherichia coli. We constructed four libraries that collectively contain 4.1 gigabases of cloned soil DNA. From these and two previously reported libraries, we identified nine clones expressing resistance to aminoglycoside antibiotics and one expressing tetracycline resistance. Based on the predicted amino acid sequences of the resistance genes, the resistance mechanisms include efflux of tetracycline and inactivation of aminoglycoside antibiotics by phosphorylation and acetylation. With one exception, all the sequences are considerably different from previously reported sequences. The results indicate that soil bacteria are a reservoir of antibiotic resistance genes with greater genetic diversity than previously accounted for, and that the diversity can be surveyed by a culture-independent method. | 2004 | 15305923 |
| 4660 | 19 | 0.9995 | Recovery of new integron classes from environmental DNA. Integrons are genetic elements known for their role in the acquisition and expression of genes conferring antibiotic resistance. Such acquisition is mediated by an integron-encoded integrase, which captures genes that are part of gene cassettes. To test whether integrons occur in environments with no known history of antibiotic exposure, PCR primers were designed to conserved regions of the integrase gene and the gene cassette recombination site. Amplicons generated from four environmental DNA samples contained features typical of the integrons found in antibiotic-resistant and pathogenic bacteria. The sequence diversity of the integrase genes in these clones was sufficient to classify them within three new classes of integron. Since they are derived from environments not associated with antibiotic use, integrons appear to be more prevalent in bacteria than previously observed. | 2001 | 11166996 |