scholarly journals Comparative Analysis of Sequences Flanking tet(W) Resistance Genes in Multiple Species of Gut Bacteria

2006 ◽  
Vol 50 (8) ◽  
pp. 2632-2639 ◽  
Author(s):  
Katarzyna A. Kazimierczak ◽  
Harry J. Flint ◽  
Karen P. Scott
Keyword(s):  
Resistance Genes ◽  
Bifidobacterium Longum ◽  
Tetracycline Resistance ◽  
Direct Repeats ◽  
Low Frequencies ◽  
Butyrivibrio Fibrisolvens ◽  
Reading Frame ◽  
Conjugative Transposons ◽  
Tetracycline Resistance Genes ◽  
Multiple Species

ABSTRACT 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.

scholarly journals Presence of the tet(O) Gene in Erythromycin- and Tetracycline-Resistant Strains of Streptococcus pyogenes and Linkage with either the mef(A) or the erm(A) Gene

2003 ◽  
Vol 47 (9) ◽  
pp. 2844-2849 ◽  
Author(s):  
Eleonora Giovanetti ◽  
Andrea Brenciani ◽  
Remo Lupidi ◽  
Marilyn C. Roberts ◽  
Pietro E. Varaldo
Keyword(s):  
Streptococcus Pyogenes ◽  
Resistance Genes ◽  
Gel Electrophoresis ◽  
Tetracycline Resistance ◽  
Pulsed Field Gel Electrophoresis ◽  
M Gene ◽  
Pulsed Field ◽  
Conjugative Transposons ◽  
Tetracycline Resistance Genes ◽  
Resistant Strains

ABSTRACT Sixty-three recent Italian clinical isolates of Streptococcus pyogenes resistant to both erythromycin (MICs ≥ 1 μg/ml) and tetracycline (MICs ≥ 8 μg/ml) were genotyped for macrolide and tetracycline resistance genes. We found 19 isolates carrying the mef(A) and the tet(O) genes; 25 isolates carrying the erm(A) and tet(O) genes; and 2 isolates carrying the erm(A), tet(M), and tet(O) genes. The resistance of all erm(A)-containing isolates was inducible, but the isolates could be divided into two groups on the basis of erythromycin MICs of either >128 or 1 to 4 μg/ml. The remaining 17 isolates included 15 isolates carrying the erm(B) gene and 2 isolates carrying both the erm(B) and the mef(A) genes, with all 17 carrying the tet(M) gene. Of these, 12 carried Tn916-Tn1545-like conjugative transposons. Conjugal transfer experiments demonstrated that the tet(O) gene moved with and without the erm(A) gene and with the mef(A) gene. These studies, together with the results of pulsed-field gel electrophoresis experiments and hybridization assays with DNA probes specific for the tet(O), erm(A), and mef(A) genes, suggested a linkage of tet(O) with either erm(A) or mef(A) in erythromycin- and tetracycline-resistant S. pyogenes isolates. By amplification and sequencing experiments, we detected the tet(O) gene ca. 5.5 kb upstream from the mef(A) gene. This is the first report demonstrating the presence of the tet(O) gene in S. pyogenes and showing that it may be linked with another gene and can be moved by conjugation from one chromosome to another.

scholarly journals Mosaic Tetracycline Resistance Genes and Their Flanking Regions in Bifidobacterium thermophilum and Lactobacillus johnsonii

2007 ◽  
Vol 52 (1) ◽  
pp. 248-252 ◽  
Author(s):  
Angela H. A. M. van Hoek ◽  
Sigrid Mayrhofer ◽  
Konrad J. Domig ◽  
Ana B. Flórez ◽  
Mohammed S. Ammor ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Efflux Pump ◽  
Hot Spot ◽  
Tetracycline Resistance ◽  
Lactobacillus Johnsonii ◽  
Reading Frame ◽  
Tetracycline Resistance Genes ◽  
Upstream Part ◽  
Bifidobacterium Thermophilum ◽  
Flanking Regions

ABSTRACT For the first time, mosaic tetracycline resistance genes were identified in Lactobacillus johnsonii and in Bifidobacterium thermophilum strains. The L. johnsonii strain investigated contains a complex hybrid gene, tet(O/W/32/O/W/O), whereas the five bifidobacterial strains possess two different mosaic tet genes: i.e., tet(W/32/O) and tet(O/W). As reported by others, the crossover points of the mosaic tet gene segments were found at similar positions within the genes, suggesting a hot spot for recombination. Analysis of the sequences flanking these genes revealed that the upstream part corresponds to the 5′ end of the mosaic open reading frame. In contrast, the downstream region was shown to be more variable. Surprisingly, in one of the B. thermophilum strains a third tet determinant was identified, coding for the efflux pump Tet(L).

scholarly journals Novel Insertion Sequence- and Transposon-Mediated Genetic Rearrangements in Genomic Island SGI1 of Salmonella enterica Serovar Kentucky

2008 ◽  
Vol 52 (10) ◽  
pp. 3745-3754 ◽  
Author(s):  
Benoît Doublet ◽  
Karine Praud ◽  
Sophie Bertrand ◽  
Jean-Marc Collard ◽  
François-Xavier Weill ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Salmonella Enterica ◽  
Genomic Island ◽  
Tetracycline Resistance ◽  
Gene Clusters ◽  
Mercury Resistance ◽  
Reading Frame ◽  
Tetracycline Resistance Genes ◽  
Serovar Typhimurium ◽  
Genetic Rearrangements

ABSTRACT Salmonella genomic island 1 (SGI1) is an integrative mobilizable element that harbors a multidrug resistance (MDR) gene cluster. Since its identification in epidemic Salmonella enterica serovar Typhimurium DT104 strains, variant SGI1 MDR gene clusters conferring different MDR phenotypes have been identified in several S. enterica serovars and classified as SGI1-A to -O. A study was undertaken to characterize SGI1 from serovar Kentucky strains isolated from travelers returning from Africa. Several strains tested were found to contain the partially characterized variant SGI1-K, recently described in a serovar Kentucky strain isolated in Australia. This variant contained only one cassette array, aac(3)-Id-aadA7, and an adjacent mercury resistance module. Here, the uncharacterized part of SGI1-K was sequenced. Downstream of the mer module similar to that found in Tn21, a mosaic genetic structure was found, comprising (i) part of Tn1721 containing the tetracycline resistance genes tetR and tet(A); (ii) part of Tn5393 containing the streptomycin resistance genes strAB, IS1133, and a truncated tnpR gene; and (iii) a Tn3-like region containing the tnpR gene and the β-lactamase bla TEM-1 gene flanked by two IS26 elements in opposite orientations. The rightmost IS26 element was shown to be inserted into the S044 open reading frame of the SGI1 backbone. This variant MDR region was named SGI1-K1 according to the previously described variant SGI1-K. Other SGI1-K MDR regions due to different IS26 locations, inversion, and partial deletions were characterized and named SGI1-K2 to -K5. Two new SGI1 variants named SGI1-P1 and -P2 contained only the Tn3-like region comprising the β-lactamase bla TEM-1 gene flanked by the two IS26 elements inserted into the SGI1 backbone. Three other new variants harbored only one IS26 element inserted in place of the MDR region of SGI1 and were named SGI1-Q1 to -Q3. Thus, in serovar Kentucky, the SGI1 MDR region undergoes recombinational and insertional events of transposon and insertion sequences, resulting in a higher diversity of MDR gene clusters than previously reported and consequently a higher diversity of MDR phenotypes.

scholarly journals Bacterial resistance to tetracycline: mechanisms, transfer, and clinical significance.

1992 ◽  
Vol 5 (4) ◽  
pp. 387-399 ◽  
Author(s):  
B S Speer ◽  
N B Shoemaker ◽  
A A Salyers
Keyword(s):  
Resistance Genes ◽  
Bacterial Resistance ◽  
Tetracycline Resistance ◽  
Enteric Bacteria ◽  
Resistance Mechanisms ◽  
Gram Positive ◽  
Gram Negative ◽  
Conjugative Transposons ◽  
Tetracycline Resistance Genes ◽  
Attenuation Mechanism

Tetracycline has been a widely used antibiotic because of its low toxicity and broad spectrum of activity. However, its clinical usefulness has been declining because of the appearance of an increasing number of tetracycline-resistant isolates of clinically important bacteria. Two types of resistance mechanisms predominate: tetracycline efflux and ribosomal protection. A third mechanism of resistance, tetracycline modification, has been identified, but its clinical relevance is still unclear. For some tetracycline resistance genes, expression is regulated. In efflux genes found in gram-negative enteric bacteria, regulation is via a repressor that interacts with tetracycline. Gram-positive efflux genes appear to be regulated by an attenuation mechanism. Recently it was reported that at least one of the ribosome protection genes is regulated by attenuation. Tetracycline resistance genes are often found on transmissible elements. Efflux resistance genes are generally found on plasmids, whereas genes involved in ribosome protection have been found on both plasmids and self-transmissible chromosomal elements (conjugative transposons). One class of conjugative transposon, originally found in streptococci, can transfer itself from streptococci to a variety of recipients, including other gram-positive bacteria, gram-negative bacteria, and mycoplasmas. Another class of conjugative transposons has been found in the Bacteroides group. An unusual feature of the Bacteroides elements is that their transfer is enhanced by preexposure to tetracycline. Thus, tetracycline has the double effect of selecting for recipients that acquire a resistance gene and stimulating transfer of the gene.

scholarly journals Antimicrobial Use and Resistance in Swine Waste Treatment Systems

2006 ◽  
Vol 72 (12) ◽  
pp. 7813-7820 ◽  
Author(s):  
Archana Jindal ◽  
Svetlana Kocherginskaya ◽  
Asma Mehboob ◽  
Matthew Robert ◽  
Roderick I. Mackie ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Waste Treatment ◽  
Growth Promotion ◽  
Tetracycline Resistance ◽  
Land Application ◽  
Molecular Methods ◽  
23S Rrna ◽  
Organic Farm ◽  
Tetracycline Resistance Genes ◽  
Fecal Streptococci

ABSTRACT Chlortetracycline and the macrolide tylosin were identified as commonly used antimicrobials for growth promotion and prophylaxis in swine production. Resistance to these antimicrobials was measured throughout the waste treatment processes at five swine farms by culture-based and molecular methods. Conventional farm samples had the highest levels of resistance with both culture-based and molecular methods and had similar levels of resistance despite differences in antimicrobial usage. The levels of resistance in organic farm samples, where no antimicrobials were used, were very low by a culture-based method targeting fecal streptococci. However, when the same samples were analyzed with a molecular method detecting methylation of a specific nucleotide in the 23S rRNA that results in resistance to macrolides, lincosamides, and streptogramin B (MLSB), an unexpectedly high level of resistant rRNA (approximately 50%) was observed, suggesting that the fecal streptococci were not an appropriate target group to evaluate resistance in the overall microbial community and that background levels of MLSB resistance may be substantial. All of the feed samples tested, including those from the organic farm, contained tetracycline resistance genes. Generally, the same tetracycline resistance genes and frequency of detection were found in the manure and lagoon samples for each commercial farm. The levels of tetracycline and MLSB resistance remained high throughout the waste treatment systems, suggesting that the potential impact of land application of treated wastes and waste treatment by-products on environmental levels of resistance should be investigated further.

Abundances of Tetracycline Resistance Genes and Tetracycline Antibiotics during Anaerobic Digestion of Swine Waste

2019 ◽  
Vol 48 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Melanie Couch ◽  
Getahun E. Agga ◽  
John Kasumba ◽  
Rohan R. Parekh ◽  
John H. Loughrin ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Resistance Genes ◽  
Tetracycline Resistance ◽  
Swine Waste ◽  
Tetracycline Antibiotics ◽  
Tetracycline Resistance Genes

scholarly journals Tetracycline Susceptibility Testing and Resistance Genes in Isolates of Acinetobacter baumannii-Acinetobacter calcoaceticus Complex from a U.S. Military Hospital

2009 ◽  
Vol 53 (6) ◽  
pp. 2693-2695 ◽  
Author(s):  
Kevin S. Akers ◽  
Katrin Mende ◽  
Heather C. Yun ◽  
Duane R. Hospenthal ◽  
Miriam L. Beckius ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Susceptibility Testing ◽  
Tetracycline Resistance ◽  
Acinetobacter Calcoaceticus ◽  
Multidrug Resistant ◽  
Military Hospital ◽  
Tetracycline Resistance Genes ◽  
Testing Method

ABSTRACT Infections with multidrug-resistant Acinetobacter baumannii-Acinetobacter calcoaceticus complex bacteria complicate the care of U.S. military personnel and civilians worldwide. One hundred thirty-three isolates from 89 patients at our facility during 2006 and 2007 were tested by disk diffusion, Etest, and broth microdilution for susceptibility to tetracycline, doxycycline, minocycline, and tigecycline. Minocycline was the most active in vitro, with 90% of the isolates tested susceptible. Susceptibilities varied significantly with the testing method. The acquired tetracycline resistance genes tetA, tetB, and tetA(39) were present in the isolates.

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