scholarly journals IntI2 Integron Integrase in Tn7

2002 ◽  
Vol 184 (6) ◽  
pp. 1712-1721 ◽  
Author(s):  
Karin Hansson ◽  
Lars Sundström ◽  
Alex Pelletier ◽  
Paul H. Roy
Keyword(s):  
Amino Acids ◽  
Antibiotic Resistance ◽  
Stop Codon ◽  
Antibiotic Resistance Genes ◽  
Peptide Sequence ◽  
Integrase Gene ◽  
Site Specific ◽  
Class 1 Integrons ◽  
Parental Allele ◽  
Class 1

ABSTRACT Integrons can insert and excise antibiotic resistance genes on plasmids in bacteria by site-specific recombination. Class 1 integrons code for an integrase, IntI1 (337 amino acids in length), and are generally borne on elements derived from Tn5090, such as that found in the central part of Tn21. A second class of integron is found on transposon Tn7 and its relatives. We have completed the sequence of the Tn7 integrase gene, intI2, which contains an internal stop codon. This codon was found to be conserved among intI2 genes on three other Tn7-like transposons harboring different cassettes. The predicted peptide sequence (IntI2*) is 325 amino acids long and is 46% identical to IntI1. In order to detect recombination activity, the internal stop codon at position 179 in the parental allele was changed to a triplet coding for glutamic acid. The sequences flanking the cassette arrays in the class 1 and 2 integrons are not closely related, but a common pool of mobile cassettes is used by the different integron classes; two of the three antibiotic resistance cassettes on Tn7 and its close relatives are also found in various class 1 integrons. We also observed a fourth excisable cassette downstream of those described previously in Tn7. The fourth cassette encodes a 165-amino-acid protein of unknown function with 6.5 contiguous repeats of a sequence coding for 7 amino acids. IntI2*179E promoted site-specific excision of each of the cassettes in Tn7 at different frequencies. The integrases from Tn21 and Tn7 showed limited cross-specificity in that IntI1 could excise all cassettes from both Tn21 and Tn7. However, we did not observe a corresponding excision of the aadA1 cassette from Tn21 by IntI2*179E.

scholarly journals The Evolution of Class 1 Integrons and the Rise of Antibiotic Resistance

2008 ◽  
Vol 190 (14) ◽  
pp. 5095-5100 ◽  
Author(s):  
Michael Gillings ◽  
Yan Boucher ◽  
Maurizio Labbate ◽  
Andrew Holmes ◽  
Samyuktha Krishnan ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Lateral Transfer ◽  
Natural Environments ◽  
Class 1 Integrons ◽  
Wide Range ◽  
Human Food Chain ◽  
Class 1 ◽  
Phylogenetic Signature

ABSTRACT Class 1 integrons are central players in the worldwide problem of antibiotic resistance, because they can capture and express diverse resistance genes. In addition, they are often embedded in promiscuous plasmids and transposons, facilitating their lateral transfer into a wide range of pathogens. Understanding the origin of these elements is important for the practical control of antibiotic resistance and for exploring how lateral gene transfer can seriously impact on, and be impacted by, human activities. We now show that class 1 integrons can be found on the chromosomes of nonpathogenic soil and freshwater Betaproteobacteria. Here they exhibit structural and sequence diversity, an absence of antibiotic resistance genes, and a phylogenetic signature of lateral transfer. Some examples are almost identical to the core of the class 1 integrons now found in pathogens, leading us to conclude that environmental Betaproteobacteria were the original source of these genetic elements. Because these elements appear to be readily mobilized, their lateral transfer into human commensals and pathogens was inevitable, especially given that Betaproteobacteria carrying class 1 integrons are common in natural environments that intersect with the human food chain. The strong selection pressure imposed by the human use of antimicrobial compounds then ensured their fixation and global spread into new species.

scholarly journals Incidence, Distribution, and Spread of Tetracycline Resistance Determinants and Integron-Associated Antibiotic Resistance Genes among Motile Aeromonads from a Fish Farming Environment

2001 ◽  
Vol 67 (12) ◽  
pp. 5675-5682 ◽  
Author(s):  
Anja S. Schmidt ◽  
Morten S. Bruun ◽  
Inger Dalsgaard ◽  
Jens L. Larsen
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Tetracycline Resistance ◽  
Class 1 Integron ◽  
Gene Cassettes ◽  
Class 1 Integrons ◽  
Resistance Determinants ◽  
Class 1

ABSTRACT A collection of 313 motile aeromonads isolated at Danish rainbow trout farms was analyzed to identify some of the genes involved in high levels of antimicrobial resistance found in a previous field trial (A. S. Schmidt, M. S. Bruun, I. Dalsgaard, K. Pedersen, and J. L. Larsen, Appl. Environ. Microbiol. 66:4908–4915, 2000), the predominant resistance phenotype (37%) being a combined oxytetracycline (OTC) and sulphadiazine/trimethoprim resistance. Combined sulphonamide/trimethoprim resistance (135 isolates) appeared closely related to the presence of a class 1 integron (141 strains). Among the isolates containing integrons, four different combinations of integrated resistance gene cassettes occurred, in all cases including a dihydrofolate reductase gene and a downstream aminoglycoside resistance insert (87 isolates) and occasionally an additional chloramphenicol resistance gene cassette (31 isolates). In addition, 23 isolates had “empty” integrons without inserted gene cassettes. As far as OTC resistance was concerned, only 66 (30%) out of 216 resistant aeromonads could be assigned to resistance determinant class A (19 isolates), D (n = 6), or E (n = 39); three isolates contained two tetracycline resistance determinants (AD, AE, and DE). Forty OTC-resistant isolates containing large plasmids were selected as donors in a conjugation assay, 27 of which also contained a class 1 integron. Out of 17 successful R-plasmid transfers to Escherichia coli recipients, the respective integrons were cotransferred along with the tetracycline resistance determinants in 15 matings. Transconjugants were predominantly tetApositive (10 of 17) and contained class 1 integrons with two or more inserted antibiotic resistance genes. While there appeared to be a positive correlation between conjugative R-plasmids andtetA among the OTC-resistant aeromonads, tetEand the unclassified OTC resistance genes as well as class 1 integrons were equally distributed among isolates with and without plasmids. These findings indicate the implication of other mechanisms of gene transfer besides plasmid transfer in the dissemination of antibiotic resistance among environmental motile aeromonads.

scholarly journals Characterization of Vibrio parahaemolyticus strains isolated in Chile in 2005 and in 2007

2010 ◽  
Vol 5 (07) ◽  
pp. 502-510 ◽  
Author(s):  
Priscila Dauros ◽  
Helia Bello ◽  
Mariana Domínguez ◽  
Juan C. Hormazábal ◽  
Gerardo González
Keyword(s):  
Antibiotic Resistance ◽  
Antibiotic Resistance Genes ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Disk Diffusion Method ◽  
Integrase Gene ◽  
Class 1 ◽  
Single Clone ◽  
Almost All ◽  
Pfge Profiles

Introduction: Vibrio (V.) parahaemolyticus has endemically established in Chilean sea shores, causing outbreaks every year, with an important number of cases. In order to know the genetic relationship, genotype dominance and antibiotic resistance of isolates obtained from two outbreaks, this study characterized 110 strains isolated from environmental and clinical samples in years 2005 and 2007 in Chile. Methodology: Genotyping was performed by determination of PFGE profiles, and pandemic group and integrons were screened by PCR. Antimicrobial susceptibility was studied by the disk diffusion method. Results: High antibiotic susceptibility frequency was found, mainly among 2007 isolates, except to ampicillin, cephalothin, cefoxitin, cefpodoxime, amikacin, streptomycin and kanamycin. Strains belonging to the pandemic group in clinical isolates account for 88% in 2005, decreasing to 66% in 2007 and among environmental isolates were detected in 20% of the strains from 2005, rising to 36% in 2007. In 2005, nine different PFGE profiles were identified, with 78% of the strains corresponding to a single clone. In 2007, sixteen different PFGE profiles were detected, with 61% of the strains included into a sole clone. The same clone was prevalent in both years. None of class 1, 2, 3 and SXT integrases genes was detected; however, the superintegron integrase gene (intIA) was present in almost all strains. Conclusions: These results suggest the persistence and dominance of a unique PFGE clone of V. parahaemolyticus during 2005 and 2007, and the absence of genetic elements that capture antibiotic resistance genes described in other species of Vibrio.

scholarly journals Prevalence of class 1 and 2 integrons among the multidrug resistant uropathogenic strains of Escherichia coli

2017 ◽  
Vol 9 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Haddadi Azam ◽  
Somayeh Mikaili Ghezeljeh ◽  
Shavandi Mahmoud
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Disk Diffusion Method ◽  
Integrase Gene ◽  
Class 1 ◽  
Tract Infections

Abstract Background Multidrug resistance is a serious problem in the treatment of urinary tract infections. Horizontal gene transfer, directed by strong selective pressure of antibiotics, has resulted in the widespread distribution of multiple antibiotic resistance genes. The dissemination of resistance genes is enhanced when they are trapped in integrons. Objectives To determine the prevalence of integrons among multidrug resistant Escherichia coli strains collected from regional hospitals and private clinical laboratories in Alborz province. Methods The susceptibility of 111 clinical Escherichia coli isolates was tested using a Kirby–Bauer disk diffusion method for common antibiotics. Isolates were screened for the production of extended spectrum β-lactamases (ESBLs) using a double disk synergy test. The existence of integrons was confirmed by amplification of the integrase gene and their class determined via analysis of PCR products by PCR-RFLP. Results Isolates showed the highest resistance to amoxicillin. Nitrofurantoin, amikacin, and ceftizoxime were the most effective antibiotics in vitro. Eighty-eight isolates of 111 (79%) were resistant to more than three unrelated drugs. We found 30% of the multidrug resistant isolates harbor integrons. Class 1 and 2 integrons were detected in 25 and 1 isolates, respectively. ESBL screening of strains showed 45 isolates (40%) were positive; 22% of the ESBL-positive isolates carried class 1 integrons and the frequency of MDR in ESBLpositive isolates was 93%. Conclusion The existence of integrons in only 29.5% of multidrug resistant isolates showed that besides integrons, antibiotic resistance genes were probably carried on other transferable elements lacking integrons, such as transposons or plasmids.

scholarly journals Analysis of Class 1 Integrons and Antibiotic Resistance Genes in Pseudomonas aeruginosa Strains from Benin City, Nigeria

2020 ◽  
Vol 24 (4) ◽  
pp. 633-637
Author(s):  
B.O. Isichei-Ukah ◽  
O.I. Enabulele
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Environmental Isolates ◽  
Significance Level ◽  
Beta Lactamases ◽  
Class 1 Integrons ◽  
Benin City ◽  
Class 1

The presence of integrons and antibiotic resistance genes in the genome of Pseudomonas aeruginosa pose a serious problem in the treatment and control of infections caused by this pathogen in hospitals. This study was carried to analyse the presence of class 1 integrons and some antibiotic resistance genes on selected clinical and environmental strains of Pseudomonas aeruginosa. A total of 120 strains were employed for this study.The strains were confirmed using molecular method and species-specific primers targeting the 16S ribosomal ribonucleic acid (rRNA). Polymerase chain reaction (PCR) was used to detect the presence of class 1 integrons and resistance genes using appropriate primers and conditions. The strains were analysed for the presence of the following antibiotic resistance genes - aadA, blaPSE, blaAMPC, blaIMP and tetC encoding  aminoglycosides, betalactamases, metallo-beta-lactamases (MBL) and tetracylines resistance respectively. On screening the isolates for the presence of class 1 integrons, 50/60 (83.3 %) clinical isolates and 46/60 (76.7 %) environmental isolates showed positive results (P > 0.05). In both clinical and environmental isolates, the highest occurring resistance genes were blaAMPC and tetC (encoding beta-lactamases and tetracylines respectively), while the least was observed in blaIMP (encoding metallo-beta-lactamases). In comparison, there was high significance difference (at P<0.01 significance level) in the resistance gene blaPSE between the clinical and environmental strains. The high prevalence of these resistance genes is a great threat in the treatment of Pseudomonas infections. Keywords: Pseudomonas aeruginosa, Resistance genes, Integrons, Beta-lactamases.

Comparison of integron-linked antibiotic resistance genes in strains of Salmonella spp. isolated from swine in Chile in 2005 and 2008

2010 ◽  
Vol 56 (6) ◽  
pp. 515-521 ◽  
Author(s):  
Lisette Lapierre ◽  
Betty San Martín ◽  
Carolina Araya-Jordán ◽  
Consuelo Borie
Keyword(s):  
Antibiotic Resistance ◽  
Clavulanic Acid ◽  
Resistance Genes ◽  
Geographical Area ◽  
Antibiotic Resistance Genes ◽  
Gene Cassette ◽  
Salmonella Spp ◽  
Single Class ◽  
Class 1 Integrons ◽  
Class 1

Salmonella spp. isolates obtained from healthy swine in 2008 were analyzed for antibiotic resistance phenotypes and genotypes. The resistance profiles of the 2008 isolates were compared with those of a Salmonella collection isolated from the same geographical area in 2005. The 2008 isolates consisted of strains that were 97% oxytetracycline resistant, 33.3% amoxicillin resistant, 31.8% amoxicillin- plus clavulanic acid resistant, 27.5% trimethoprim–sulfamethoxazole resistant, 17.3% streptomycin resistant, and 7.2% enrofloxacin–ciprofloxacin resistant. The presence of integrons and resistance genes and their topological association in resistant strains was assessed by PCR. The prevalence of class 1 integrons was the highest, at 46.2%, while class 2 integrons were present in 17.9% of the isolates. In strains that harboured class 1 integrons, we identified 3 different gene cassette arrangements; a single class 2 integron arrangement of dfrA1–sat1–aadA1 was found. Comparison of these results with data obtained from the 2005 isolates showed that Salmonella strains resistant to amoxicillin and amoxicillin plus clavulanic acid had clearly emerged over the span of 3 years, along with an increase in the prevalence of class 1 integrons and the acquisition of new gene cassette arrangements. These findings highlight the need for continual monitoring of regional isolates to establish more efficient vigilance programs that can address variations in resistance over short periods of time within the same geographical area.

scholarly journals Class 1 Integrons Potentially Predating the Association with Tn402-Like Transposition Genes Are Present in a Sediment Microbial Community

2006 ◽  
Vol 188 (16) ◽  
pp. 5722-5730 ◽  
Author(s):  
H. W. Stokes ◽  
Camilla L. Nesbø ◽  
Marita Holley ◽  
Martin I. Bahl ◽  
Michael R. Gillings ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Bacterial Species ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Global Scale ◽  
Human Pathogens ◽  
Class 1 Integrons ◽  
Recombination System ◽  
Class 1

ABSTRACT Integrons are genetic elements that contribute to lateral gene transfer in bacteria as a consequence of possessing a site-specific recombination system. This system facilitates the spread of genes when they are part of mobile cassettes. Most integrons are contained within chromosomes and are confined to specific bacterial lineages. However, this is not the case for class 1 integrons, which were the first to be identified and are one of the single biggest contributors to multidrug-resistant nosocomial infections, carrying resistance to many antibiotics in diverse pathogens on a global scale. The rapid spread of class 1 integrons in the last 60 years is partly a result of their association with a specific suite of transposition functions, which has facilitated their recruitment by plasmids and other transposons. The widespread use of antibiotics has acted as a positive selection pressure for bacteria, especially pathogens, which harbor class 1 integrons and their associated antibiotic resistance genes. Here, we have isolated bacteria from soil and sediment in the absence of antibiotic selection. Class 1 integrons were recovered from four different bacterial species not known to be human pathogens or commensals. All four integrons lacked the transposition genes previously considered to be a characteristic of this class. At least two of these integrons were located on a chromosome, and none of them possessed antibiotic resistance genes. We conclude that novel class 1 integrons are present in a sediment environment in various bacteria of the β-proteobacterial class. These data suggest that the dispersal of this class may have begun before the “antibiotic era.”

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