# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 3571 | 0 | 1.0000 | Evidence for recent intergeneric transfer of a new tetracycline resistance gene, tet(W), isolated from Butyrivibrio fibrisolvens, and the occurrence of tet(O) in ruminal bacteria. We have previously reported high-frequency transfer of tetracycline resistance between strains of the rumen anaerobic bacterium Butyrivibrio fibrisolvens. Donor strains were postulated to carry two TcR genes, one of which is transferred on a novel chromosomal element. It is shown here that coding sequences within the non-transmissible gene in B. fibrisolvens 1.230 are identical to those of the Streptococcus pneumoniae tet(O) gene. This provides the first evidence for genetic exchange between facultatively anaerobic bacteria and rumen obligate anaerobes. In contrast, the product of the transmissible TcR gene shares only 68% amino acid sequence identity with the TetO and TetM proteins and represents a new class of ribosome protection tetracycline resistance determinant, designated Tet W. The tet(W) coding region shows a higher DNA G + C content (53%) than other B. fibrisolvens genes or other ribosome protection-type tet genes, suggesting recent acquisition from a high G + C content genome. Tet(W) genes with almost identical sequences are also shown to be present in TcR strains of B. fibrisolvens from Australian sheep and in TcR strains of two other genera of rumen obligate anaerobes, Selenomonas ruminantium and Mitsuokella multiacidus. This provides compelling evidence for recent intergeneric transfer of resistance genes between ruminal bacteria. Tet(W) is not restricted to ruminal bacteria, as it was also present in a porcine strain of M. multiacidus. | 1999 | 11207718 |
| 4501 | 1 | 0.9997 | A Bacteroides tetracycline resistance gene represents a new class of ribosome protection tetracycline resistance. The ribosome protection type of tetracycline resistance (Tcr) has been found in a variety of bacterial species, but the only two classes described previously, Tet(M) and Tet(O), shared a high degree of amino acid sequence identity (greater than 75%). Thus, it appeared that this type of resistance emerged recently in evolution and spread among different species of bacteria by horizontal transmission. We obtained the DNA sequence of a Tcr gene from Bacteroides, a genus of gram-negative, obligately anaerobic bacteria that is phylogenetically distant from the diverse species in which tet(M) and tet(O) have been found. The Bacteroides Tcr gene defines a new class of ribosome protection resistance genes, Tet(Q), and has a deduced amino acid sequence that was only 40% identical to Tet(M) or Tet(O). Like tet(M) and tet(O), tet(Q) appears to have spread by horizontal transmission, but only within the Bacteroides group. | 1992 | 1339256 |
| 3572 | 2 | 0.9997 | Comparative analysis of sequences flanking tet(W) resistance genes in multiple species of gut bacteria. tet(W) is one of the most abundant tetracycline resistance genes found in bacteria from the mammalian gut and was first identified in the rumen anaerobe Butyrivibrio fibrisolvens 1.230, where it is highly mobile and its transfer is associated with the transposable chromosomal element TnB1230. In order to compare the genetic basis for tet(W) carriage in different bacteria, we studied sequences flanking tet(W) in representatives of seven bacterial genera originating in diverse gut environments. The sequences 657 bp upstream and 43 bp downstream of tet(W) were 96 to 100% similar in all strains examined. A common open reading frame (ORF) was identified downstream of tet(W) in five different bacteria, while another conserved ORF that flanked tet(W) in B. fibrisolvens 1.230 was also present upstream of tet(W) in a human colonic Roseburia isolate and in another rumen B. fibrisolvens isolate. In one species, Bifidobacterium longum (strain F8), a novel transposase was located within the conserved 657-bp region upstream of tet(W) and was flanked by imperfect direct repeats. Additional direct repeats 6 bp long were identified on each end of a chromosomal ORF interrupted by the insertion of the putative transposase and the tet(W) gene. This tet(W) gene was transferable at low frequencies between Bifidobacterium strains. A putative minielement carrying a copy of tet(W) was identified in B. fibrisolvens transconjugants that had acquired the tet(W) gene on TnB1230. Several different mechanisms, including mechanisms involving plasmids and conjugative transposons, appear to be involved in the horizontal transfer of tet(W) genes, but small core regions that may function as minielements are conserved. | 2006 | 16870752 |
| 4500 | 3 | 0.9997 | Mosaic tetracycline resistance genes encoding ribosomal protection proteins. First reported in 2003, mosaic tetracycline resistance genes are a subgroup of the genes encoding ribosomal protection proteins (RPPs). They are formed when two or more RPP-encoding genes recombine resulting in a functional chimera. To date, the majority of mosaic genes are derived from sections of three RPP genes, tet(O), tet(W) and tet(32), with others comprising tet(M) and tet(S). In this first review of mosaic genes, we report on their structure, diversity and prevalence, and suggest that these genes may be responsible for an under-reported contribution to tetracycline resistance in bacteria. | 2016 | 27494928 |
| 3568 | 4 | 0.9996 | Occurrence of the new tetracycline resistance gene tet(W) in bacteria from the human gut. Members of our group recently identified a new tetracycline resistance gene, tet(W), in three genera of rumen obligate anaerobes. Here, we show that tet(W) is also present in bacteria isolated from human feces. The tet(W) genes found in human Fusobacterium prausnitzii and Bifidobacterium longum isolates were more than 99.9% identical to those from a rumen isolate of Butyrivibrio fibrisolvens. | 2000 | 10681357 |
| 4526 | 5 | 0.9996 | The tetracycline resistance gene tet(M) exhibits mosaic structure. Tetracycline resistance genes of the M class, tet(M), are typically found on mobile genetic elements as the conjugative transposons of gram-positive bacteria. By comparing the sequences of eight different tet(M) genes (from Enterococcus faecalis, Streptococcus pneumoniae, Staphylococcus aureus, Ureaplasma urealyticum, and Neisseria), a mosaic structure was detected which could be traced to two distinct alleles. The two alleles displayed a divergence of 8% and a different G/C content. The block structure of these genes provides evidence for the contribution of homologous recombination to the evolution and the heterogeneity of the tet(M) locus. Unlike described cases of chromosomally located mosaic loci, tet(M) is a relatively recently acquired determinant in the species examined and it would appear that mosaic structure within tet(M) has evolved after acquisition of the gene by the mobile genetic elements upon which it is located. | 1996 | 8812782 |
| 4499 | 6 | 0.9996 | Organization of two sulfonamide resistance genes on plasmids of gram-negative bacteria. The organization of two widely distributed sulfonamide resistance genes has been studied. The type I gene was linked to other resistance genes, like streptomycin resistance in R100 and trimethoprim resistance in R388 and other recently isolated plasmids from Sri Lanka. In R388, the sulfonamide resistance gene was transcribed from a promoter of its own, but in all other studied plasmids the linked genes were transcribed from a common promoter. This was especially established with a clone derived from plasmid R6-5, in which transposon mutagenesis showed that expression of sulfonamide resistance was completely dependent on the linked streptomycin resistance gene. The type II sulfonamide resistance gene was independently transcribed and found on two kinds of small resistance plasmids and also on large plasmids isolated from clinical material. | 1987 | 3032095 |
| 4465 | 7 | 0.9995 | Genetic analyses of sulfonamide resistance and its dissemination in gram-negative bacteria illustrate new aspects of R plasmid evolution. In contrast to what has been observed for many other antibiotic resistance mechanisms, there are only two known genes encoding plasmid-borne sulfonamide resistance. Both genes, sulI and sulII, encode a drug-resistant dihydropteroate synthase enzyme. In members of the family Enterobacteriaceae isolated from several worldwide sources, plasmid-mediated resistance to sulfonamides could be identified by colony hybridization as being encoded by sulI, sulII, or both. The sulI gene was in all cases found to be located in the newly defined, mobile genetic element, recently named an integron, which has been shown to contain a site-specific recombination system for the integration of various antibiotic resistance genes. The sulII gene was almost exclusively found as part of a variable resistance region on small, nonconjugative plasmids. Colony hybridization to an intragenic probe, restriction enzyme digestion, and nucleotide sequence analysis of small plasmids indicated that the sulII gene and contiguous sequences represent an independently occurring region disseminated in the bacterial population. The sulII resistance region was bordered by direct repeats, which in some plasmids were totally or partially deleted. The prevalence of sulI and sulII could thus be accounted for by their stable integration in transposons and in plasmids that are widely disseminated among gram-negative bacteria. | 1991 | 1952855 |
| 9821 | 8 | 0.9995 | Mercury resistance (mer) operons in enterobacteria. Mercury resistance is found in many genera of bacteria. Common amongst enterobacteria are transposons related to Tn21, which is both mercuric ion- and streptomycin-/spectinomycin- and sulphonamide-resistant. Other Tn21-related transposons often have different antibiotic resistances compared with Tn21, but share many non-antibiotic-resistance genes with it. In this article we discuss possible mechanisms for the evolution of Tn21 and related genetic elements. | 2002 | 12196175 |
| 3579 | 9 | 0.9995 | The Tetracycline Resistance Gene, tet(W) in Bifidobacterium animalis subsp. lactis Follows Phylogeny and Differs From tet(W) in Other Species. The tetracycline resistance gene tet(W) encodes a ribosomal protection protein that confers a low level of tetracycline resistance in the probiotic bacterium Bifidobacterium animalis subsp. lactis. With the aim of assessing its phylogenetic origin and potential mobility, we have performed phylogenetic and in silico genome analysis of tet(W) and its flanking genes. tet(W) was found in 41 out of 44 examined B. animalis subsp. lactis strains. In 38 strains, tet(W) was flanked by an IS5-like element and an open reading frame encoding a hypothetical protein, which exhibited a similar GC content (51-53%). These genes were positioned in the same genomic context within the examined genomes. Phylogenetically, the B. animalis subsp. lactis tet(W) cluster in a clade separate from tet(W) of other species and genera. This is not the case for tet(W) encoded by other bifidobacteria and other species where tet(W) is often found in association with transferable elements or in different genomic regions. An IS5-like element identical to the one flanking the B. animalis subsp. lactis tet(W) has been found in a human gut related bacterium, but it was not associated with any tet(W) genes. This suggests that the IS5-like element is not associated with genetic mobility. tet(W) and the IS5 element have previously been shown to be co-transcribed, indicating that co-localization may be associated with tet(W) expression. Here, we present a method where phylogenetic and in silico genome analysis can be used to determine whether antibiotic resistance genes should be considered innate (intrinsic) or acquired. We find that B. animalis subsp. lactis encoded tet(W) is part of the ancient resistome and thereby possess a negligible risk of transfer. | 2021 | 34335493 |
| 4503 | 10 | 0.9995 | Evolution and transfer of aminoglycoside resistance genes under natural conditions. 3'-Aminoglycoside phosphotransferases [APH(3')] were chosen as a model to study the evolution and the transfer of aminoglycoside resistance genes under natural conditions. Comparison of the amino acid sequences of APH(3') enzymes from transposons Tn903 (type I) and Tn5 (type II) detected in Gram-negative bacteria, from the Gram-positive Staphylococcus and Streptococcus (type III), from the butirosin-producing Bacillus circulans (type IV) and from a neomycin-producing Streptomyces fradiae (type V) indicate that they have diverged from a common ancestor. These structural data support the hypothesis that the antibiotic-producing strains were the source of certain resistance determinants. We have shown that kanamycin resistance in Campylobacter coli BM2509 was due to the synthesis of an APH(3')-III, an enzyme not detected previously in a Gram-negative bacterium. The genes encoding APH(3')-III in Streptococcus and Campylobacter are identical. These findings constitute evidence for a recent in-vivo transfer of DNA between Gram-positive and Gram-negative bacteria. | 1986 | 3027020 |
| 416 | 11 | 0.9995 | Characterization of In0 of Pseudomonas aeruginosa plasmid pVS1, an ancestor of integrons of multiresistance plasmids and transposons of gram-negative bacteria. Many multiresistance plasmids and transposons of gram-negative bacteria carry related DNA elements that appear to have evolved from a common ancestor by site-specific integration of discrete cassettes containing antibiotic resistance genes or sequences of unknown function. The site of integration is flanked by conserved segments coding for an integraselike protein and for sulfonamide resistance, respectively. These segments, together with the antibiotic resistance genes between them, have been termed integrons (H. W. Stokes and R. M. Hall, Mol. Microbiol. 3:1669-1683, 1989). We report here the characterization of an integron, In0, from Pseudomonas aeruginosa plasmid pVS1, which has an unoccupied integration site and hence may be an ancestor of more complex integrons. Codon usage of the integrase (int) and sulfonamide resistance (sul1) genes carried by this integron suggests a common origin. This contrasts with the codon usage of other antibiotic resistance genes that were presumably integrated later as cassettes during the evolution and spread of these DNA elements. We propose evolutionary schemes for (i) the genesis of the integrons by the site-specific integration of antibiotic resistance genes and (ii) the evolution of the integrons of multiresistance plasmids and transposons, in relation to the evolution of transposons related to Tn21. | 1992 | 1310501 |
| 3587 | 12 | 0.9995 | Distribution of the streptomycin-resistance transposon Tn5393 among phylloplane and soil bacteria from managed agricultural habitats. The distribution of the strA-strB streptomycin-resistance (Smr) genes associated with Tn5393 was examined in bacteria isolated from the phylloplane and soil of ornamental pear and tomato. Two ornamental pear nurseries received previous foliar applications of streptomycin, whereas the tomato fields had no prior exposure to streptomycin bactericides. Although the recovery of culturable Smr bacteria was generally higher from soil, the highest occurrence of Smr was observed in phylloplane bacteria of an ornamental pear nursery that received 15 annual applications of streptomycin during the previous 2 years. Twenty-two and 12% of 143 Gram-negative phylloplane and 163 Gram-negative soil isolates, respectively, contained sequences that hybridized to probes specific for the strA-strB Smr genes and for the transposase and resolvase genes of Tn5393. These sequences were located on large plasmids (> 60 kb) in 74% of the isolates. The 77 Smr Gram-positive bacteria isolated in the present study showed no homology to the Tn5393-derived probes. Although the repeated use of a single antibiotic in clinical situations is known to favor the development of strains with resistance to other antibiotics, we found no evidence that intensive streptomycin usage in agricultural habitats favors the development of resistance to tetracycline, an antibiotic also registered for disease control on plants. The detection of Tn5393 in bacteria with no prior exposure to streptomycin suggests that this transposon is indigenous to both phylloplane and soil microbial communities. | 1995 | 7585356 |
| 3043 | 13 | 0.9995 | The role of insertions, deletions, and substitutions in the evolution of R6 related plasmids encoding aminoglycoside transferase ANT-(2"). In 7% of gram-negative bacteria resistance to gentamicin is mainly mediated by plasmid-encoded aminoglycoside transferase ANT-(2"). The genome organization of 15 aadB plasmids (42-110 kb) was analyzed by restriction and hybridization techniques. They appeared to be IncFII-like replicons but were distinct from R6 by virtue of small substitutions in the transfer region. Aminoglycoside resistance genes aadB and aadA were located on Tn21 related elements. Only one of them was able to transpose its resistance genes mer sul aadA and aadB ( Tn4000 ), the other elements were naturally occurring defective transposons. In some of these structures deletions were identified at the termini, at sul, aadA , mer or transposition function--insertions adjacent to aadA or mer. The mode of these rearrangements and their site-specificity were considered with respect to the evolution of the Tn21 transposon family. | 1984 | 6328217 |
| 3570 | 14 | 0.9995 | A newly discovered Bacteroides conjugative transposon, CTnGERM1, contains genes also found in gram-positive bacteria. Results of a recent study of antibiotic resistance genes in human colonic Bacteroides strains suggested that gene transfer events between members of this genus are fairly common. The identification of Bacteroides isolates that carried an erythromycin resistance gene, ermG, whose DNA sequence was 99% identical to that of an ermG gene found previously only in gram-positive bacteria raised the further possibility that conjugal elements were moving into Bacteroides species from other genera. Six of seven ermG-containing Bacteroides strains tested were able to transfer ermG by conjugation. One of these strains was chosen for further investigation. Results of pulsed-field gel electrophoresis experiments showed that the conjugal element carrying ermG in this strain is an integrated element about 75 kb in size. Thus, the element appears to be a conjugative transposon (CTn) and was designated CTnGERM1. CTnGERM1 proved to be unrelated to the predominant type of CTn found in Bacteroides isolates-CTns of the CTnERL/CTnDOT family-which sometimes carry another type of erm gene, ermF. A 19-kbp segment of DNA from CTnGERM1 was cloned and sequenced. A 10-kbp portion of this segment hybridized not only to DNA from all the ermG-containing strains but also to DNA from strains that did not carry ermG. Thus, CTnGERM1 seems to be part of a family of CTns, some of which have acquired ermG. The percentage of G+C content of the ermG region was significantly lower than that of the chromosome of Bacteroides species-an indication that CTnGERM1 may have entered Bacteroides strains from some other bacterial genus. A survey of strains isolated before 1970 and after 1990 suggests that the CTnGERM1 type of CTn entered Bacteroides species relatively recently. One of the genes located upstream of ermG encoded a protein that had 85% amino acid sequence identity with a macrolide efflux pump, MefA, from Streptococcus pyogenes. Our having found >90% sequence identity of two upstream genes, including mefA, and the remnants of two transposon-carried genes downstream of ermG with genes found previously only in gram-positive bacteria raises the possibility that gram-positive bacteria could have been the origin of CTnGERM1. | 2003 | 12902247 |
| 3578 | 15 | 0.9995 | Analysis of newly detected tetracycline resistance genes and their flanking sequences in human intestinal bifidobacteria. Due to tetracycline abuse, the safe bifidobacteria in the human gastrointestinal intestinal tract (GIT) may serve as a reservoir of tetracycline resistance genes. In the present investigation of 92 bifidobacterial strains originating from the human GIT, tetracycline resistance in 29 strains was mediated by the tet(W), tet(O) or tet(S) gene, and this is the first report of tet(O)- and tet(S)-mediated tetracycline resistance in bifidobacteria. Antibiotic resistance genes harbored by bifidobacteria are transferred from other bacteria. However, the characteristics of the spread and integration of tetracycline resistance genes into the human intestinal bifidobacteria chromosome are poorly understood. Here, conserved sequences were identified in bifidobacterial strains positive for tet(W), tet(O), or tet(S), including the tet(W), tet(O), or tet(S) and their partial flanking sequences, which exhibited identity with the sequences in multiple human intestinal pathogens, and genes encoding 23 S rRNA, an ATP transporter, a Cpp protein, and a membrane-spanning protein were flanking by the 1920-bp tet(W), 1920-bp tet(O), 1800-bp tet(O) and 252-bp tet(S) in bifidobacteria, respectively. These findings suggest that tetracycline resistance genes harbored by human intestinal bifidobacteria might initially be transferred from pathogens and that each kind of tetracycline resistance gene might tend to insert in the vicinity of specific bifidobacteria genes. | 2017 | 28740169 |
| 4463 | 16 | 0.9995 | Composite mobile genetic elements disseminating macrolide resistance in Streptococcus pneumoniae. Macrolide resistance in Streptococcus pneumoniae emerged in the U.S. and globally during the early 1990's. The RNA methylase encoded by erm(B) and the macrolide efflux genes mef(E) and mel were identified as the resistance determining factors. These genes are disseminated in the pneumococcus on mobile, often chimeric elements consisting of multiple smaller elements. To better understand the variety of elements encoding macrolide resistance and how they have evolved in the pre- and post-conjugate vaccine eras, the genomes of 121 invasive and ten carriage isolates from Atlanta from 1994 to 2011 were analyzed for mobile elements involved in the dissemination of macrolide resistance. The isolates were selected to provide broad coverage of the genetic variability of antibiotic resistant pneumococci and included 100 invasive isolates resistant to macrolides. Tn916-like elements carrying mef(E) and mel on the Macrolide Genetic Assembly (Mega) and erm(B) on the erm(B) element and Tn917 were integrated into the pneumococcal chromosome backbone and into larger Tn5253-like composite elements. The results reported here include identification of novel insertion sites for Mega and characterization of the insertion sites of Tn916-like elements in the pneumococcal chromosome and in larger composite elements. The data indicate that integration of elements by conjugation was infrequent compared to recombination. Thus, it appears that conjugative mobile elements allow the pneumococcus to acquire DNA from distantly related bacteria, but once integrated into a pneumococcal genome, transformation and recombination is the primary mechanism for transmission of novel DNA throughout the pneumococcal population. | 2015 | 25709602 |
| 4530 | 17 | 0.9995 | Novel conjugative transferable multiple drug resistance plasmid pAQU1 from Photobacterium damselae subsp. damselae isolated from marine aquaculture environment. The emergence of drug-resistant bacteria is a severe problem in aquaculture. The ability of drug resistance genes to transfer from a bacterial cell to another is thought to be responsible for the wide dissemination of these genes in the aquaculture environment; however, little is known about the gene transfer mechanisms in marine bacteria. In this study, we show that a tetracycline-resistant strain of Photobacterium damselae subsp. damselae, isolated from seawater at a coastal aquaculture site in Japan, harbors a novel multiple drug resistance plasmid. This plasmid named pAQU1 can be transferred to Escherichia coli by conjugation. Nucleotide sequencing showed that the plasmid was 204,052 base pairs and contained 235 predicted coding sequences. Annotation showed that pAQU1 did not have known repA, suggesting a new replicon, and contained seven drug resistance genes: bla(CARB-9)-like, floR, mph(A)-like, mef(A)-like, sul2, tet(M) and tet(B). The plasmid has a complete set of genes encoding the apparatus for the type IV secretion system with a unique duplication of traA. Phylogenetic analysis of the deduced amino acid sequence of relaxase encoded by traI in pAQU1 demonstrated that the conjugative transfer system of the plasmid belongs to MOB(H12), a sub-group of the MOB(H) plasmid family, closely related to the IncA/C type of plasmids and SXT/R391 widely distributed among species of Enterobacteriaceae and Vibrionaceae. Our data suggest that conjugative transfer is involved in horizontal gene transfer among marine bacteria and provide useful insights into the molecular basis for the dissemination of drug resistance genes among bacteria in the aquaculture environment. | 2012 | 22446310 |
| 4605 | 18 | 0.9995 | Self-transmissible multidrug resistance plasmids in Escherichia coli of the normal intestinal flora of healthy swine. The resistance genes and their surroundings on three self-transmissible plasmids found in Escherichia coli of the enteric normal flora of healthy pigs have been characterized. The resistance elements found are similar to those commonly found in clinical isolates, like the transposon Tn1721 including the Tet A tetracycline resistance determinant, Tn10 with the Tet B determinant, Tn21 including a class 1 integron with the aadA1a cassette inserted, sulII encoding sulfonamide resistance, and the strA-strB genes responsible for streptomycin resistance. The plasmids were able to mobilize into various recipients, including swine pathogens, zoonotic bacteria, and commensals when conjugation experiments were carried out. Transfer of plasmids did not require optimal conditions concerning nutrition and temperature as plasmids were transferred in 0.9% saline at room temperature, suggesting that in vivo transfer might be possible. This study shows that transferable resistance elements appearing in normal flora bacteria from animals are similar to those commonly found in clinical isolates of human origin. The results indicate a probable communication between pathogens and the normal flora with respect to exchange of resistance factors. | 2001 | 11442346 |
| 3567 | 19 | 0.9995 | Cloning and sequence analysis of ermQ, the predominant macrolide-lincosamide-streptogramin B resistance gene in Clostridium perfringens. The erythromycin resistance determinant from Clostridium perfringens JIR100 has been cloned, sequenced, and shown to be expressed in Escherichia coli. An open reading frame with sequence similarity to erm genes from other bacteria was identified and designated the ermQ gene. On the basis of comparative sequence analysis, it was concluded that the ermQ gene represented a new Erm hybridization class, designated ErmQ. Genes belonging to the ErmQ class were found to be widespread in C. perfringens, since 30 of 38 macrolide-lincosamide-streptogramin B-resistant C. perfringens strains, from diverse sources, hybridized to an ermQ-specific gene probe. The ermQ gene therefore represents the most common erythromycin resistance determinant in C. perfringens. | 1994 | 8067735 |