scholarly journals Characterization and Movement of the Class 1 Integron Known as Tn2521 and Tn1405

2002 ◽  
Vol 46 (5) ◽  
pp. 1288-1294 ◽  
Author(s):  
Sally R. Partridge ◽  
Heidi J. Brown ◽  
Ruth M. Hall

ABSTRACT Two putative transposons, Tn2521 and Tn1405, carrying determinants for the PSE-4 β-lactamase and for resistance to streptomycin, spectinomycin, and sulfonamides were previously isolated from the chromosome of Pseudomonas aeruginosa Dalgleish. Detailed mapping and determination of the complete sequence of Tn2521 revealed that it is a class 1 integron, here renamed In33, with a backbone structure identical to that of In4 from Tn1696. In33 contains two gene cassettes, blaP1 and aadA1, replacing the aacC1-orfE-aadA2-cmlA1 cassette array in In4. Although In33 does not include any transposition genes, movement of In33 (Tn2521) targeted to a single location in the IncP-1 plasmid R18-18 has been reported previously (M. I. Sinclair and B. W. Holloway, J. Bacteriol. 151:569-579, 1982). A 5-bp duplication of the target, which lies within the res site recognized by the ParA resolvase of R18-18, was present, indicating that the mechanism of movement was transposition. Together, these data indicate that class 1 integrons that are defective in self-transposition can move under appropriate circumstances. The Tn1405 isolate studied was found to represent only the cassette array of In33, which had replaced the cassette array in the recipient plasmid R388, probably by homologous recombination.

2002 ◽  
Vol 46 (8) ◽  
pp. 2400-2408 ◽  
Author(s):  
Sally R. Partridge ◽  
Christina M. Collis ◽  
Ruth M. Hall

ABSTRACT The carbenicillin, gentamicin, kanamycin, streptomycin, spectinomycin, sulfonamide, and tobramycin resistance determinants found on Pseudomonas aeruginosa plasmid R151 have previously been shown to translocate to another plasmid, R388, and it was inferred that a transposon, Tn1404, carried the resistance determinants. Sequencing of the cassette array from the plasmid known as R388::Tn1404 revealed two known gene cassettes, oxa10 and aadB, and a previously unidentified cassette determining resistance to streptomycin and spectinomycin, here designated aadA10, in the order oxa10-aadB-aadA10. These cassettes replaced the dfrB2-orfA cassette array of R388, indicating that movement of the resistance determinants from R151 to R388 resulted from recombinational exchange between two class 1 integrons rather than transposition. The AadA10 protein is most closely related to AadA6 (85% identical) and AadA7 (80% identical). The aadA10 cassette found here has only a simple site containing a 7-bp spacer derived from attI1 in place of a 59-base element and is likely to represent a derivative of the complete cassette. IntI1-mediated deletion of the aadA10 cassette was not detected, indicating that this single simple site is either inactive or only weakly active.


2001 ◽  
Vol 45 (11) ◽  
pp. 3014-3020 ◽  
Author(s):  
Sally R. Partridge ◽  
Gavin D. Recchia ◽  
H. W. Stokes ◽  
Ruth M. Hall

ABSTRACT The class 1 integron In28, found in the multidrug resistance transposon Tn1403, was found to be located in theres site of the backbone transposon and is flanked by a 5-bp direct duplication, indicating that it reached this position by transposition. In28 has a backbone structure related to that of In4, but has lost internal sequences, including the sul1gene, due to an IS6100-mediated deletion. In28 also lacks the partial copy of IS6100 found in In4 and contains different gene cassettes, blaP1, cmlA1, andaadA1. In1, the class 1 integron found in the multidrug resistance plasmid R46, is also located in a putativeres site and belongs to the In4 group. In1 has a shorter internal deletion than In28 and has also lost one end. Additional integrons with structures related to In4 were also found in databases, and most of them had also lost either one end or internal regions or both. Tn610 belongs to this group.


2015 ◽  
Vol 78 (8) ◽  
pp. 1442-1450 ◽  
Author(s):  
KANJANA CHANGKAEW ◽  
APIRADEE INTARAPUK ◽  
FUANGFA UTRARACHKIJ ◽  
CHIE NAKAJIMA ◽  
ORASA SUTHIENKUL ◽  
...  

Administration of antimicrobials to food-producing animals increases the risk of higher antimicrobial resistance in the normal intestinal flora of these animals. The present cross-sectional study was conducted to investigate antimicrobial susceptibility and extended-spectrum β-lactamase (ESBL)–producing strains and to characterize class 1 integrons in Escherichia coli in healthy swine in Thailand. All 122 of the tested isolates had drug-resistant phenotypes. High resistance was found to ampicillin (98.4% of isolates), chloramphenicol (95.9%), gentamicin (78.7%), streptomycin (77.9%), tetracycline (74.6%), and cefotaxime (72.1%). Fifty-four (44.3%) of the E. coli isolates were confirmed as ESBL-producing strains. Among them, blaCTX-M (45 isolates) and blaTEM (41 isolates) were detected. Of the blaCTX-M-positive E. coli isolates, 37 carried the blaCTX-M-1 cluster, 12 carried the blaCTX-M-9 cluster, and 5 carried both clusters. Sequence analysis revealed blaTEM-1, blaTEM-135, and blaTEM-175 in 38, 2, and 1 isolate, respectively. Eighty-seven (71%) of the 122isolates carried class 1 integrons, and eight distinct drug-resistance gene cassettes with seven different integron profiles were identified in 43 of these isolates. Gene cassettes were associated with resistance to aminoglycosides (aadA1, aadA2, aadA22, or aadA23), trimethoprim (dfrA5, dfrA12, or dfrA17), and lincosamide (linF). Genes encoding β-lactamases were not found in class 1 integrons. This study is the first to report ESBL-producing E. coli with a class 1 integron carrying the linF gene cassette in swine in Thailand. Our findings confirm that swine can be a reservoir of ESBL-producing E. coli harboring class 1 integrons, which may become a potential health risk if these integrons are transmitted to humans. Intensive analyses of animal, human, and environmental isolates are needed to control the spread of ESBL-producing E. coli strains.


2005 ◽  
Vol 49 (9) ◽  
pp. 3743-3748 ◽  
Author(s):  
Laurent Poirel ◽  
Laura Brinas ◽  
Annemie Verlinde ◽  
Louis Ide ◽  
Patrice Nordmann

ABSTRACT Screening by a double-disk synergy test identified a Pseudomonas aeruginosa isolate that produced a clavulanic acid-inhibited expanded-spectrum β-lactamase (ESBL). Cloning and sequencing identified a novel ESBL, BEL-1, weakly related to other Ambler class A ESBLs. β-Lactamase BEL-1 hydrolyzed significantly most expanded-spectrum cephalosporins and aztreonam, and its activity was inhibited by clavulanic acid, tazobactam, cefoxitin, moxalactam, and imipenem. This chromosome-encoded ESBL gene was embedded in a class 1 integron containing three other gene cassettes. In addition, this integron was bracketed by Tn1404 transposon sequences at its right end and by P. aeruginosa-specific sequences at its left end.


2001 ◽  
Vol 67 (12) ◽  
pp. 5675-5682 ◽  
Author(s):  
Anja S. Schmidt ◽  
Morten S. Bruun ◽  
Inger Dalsgaard ◽  
Jens L. Larsen

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.


2019 ◽  
Vol 40 (6) ◽  
pp. 972-978 ◽  
Author(s):  
Siamak Heidarzadeh ◽  
Yasamin Enayati Kaliji ◽  
Reza Pourpaknia ◽  
Alireza Mohammadzadeh ◽  
Mehran Ghazali-Bina ◽  
...  

Abstract The role of integrons has been highlighted in antibiotic resistance among Pseudomonas aeruginosa isolates. Therefore, we here reviewed the prevalence of class 1 integrons and their correlations with antibiotic resistance of P. aeruginosa isolated from Iranian burn patients. This review was conducted according to the guidelines of Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). Cross-sectional and cohort studies published from January 1, 2000 until December 31, 2018 were enrolled. Meta-analysis was performed by Comprehensive Meta-Analysis (CMA) software using the random effects model, Cochran’s Q, and I2 tests. Publication bias was estimated by Funnel plot and Egger’s linear regression test. Nine out of 819 studies met the eligibility criteria. The overall combined prevalence of class 1 integrons in P. aeruginosa isolates was 69% (95% confidence interval [CI]: 50.5–83%). The highest combined resistance was reported against Cloxacillin (87.7%), followed by Carbenicillin (79.1%) and Ceftriaxone (77.3%). The combined prevalence of multidrug-resistant (MDR) isolates was 79.3% (95% CI: 31.1–97%). Also, a significant correlation was noted between the presence of class 1 integrons and antibiotic resistance in 55.5% of the included studies (P < .05). The results showed high prevalence of class 1 integrons, antibiotic resistance, and MDR strains in P. aeruginosa isolated from Iranian burn patients. Also, most of the included studies showed a significant correlation between the presence of class 1 integrons and antibiotic resistance.


2005 ◽  
Vol 49 (2) ◽  
pp. 836-839 ◽  
Author(s):  
Patrícia Antunes ◽  
Jorge Machado ◽  
João Carlos Sousa ◽  
Luísa Peixe

ABSTRACT In 200 sulfonamide-resistant Portuguese Salmonella isolates, 152 sul1, 74 sul2, and 14 sul3 genes were detected. Class 1 integrons were always associated with sul genes, including sul3 alone in some isolates. The sul3 gene has been identified in isolates from different sources and serotypes, which also carried a class 1 integron with aadA and dfrA gene cassettes.


2006 ◽  
Vol 50 (8) ◽  
pp. 2741-2750 ◽  
Author(s):  
Ângela Novais ◽  
Rafael Cantón ◽  
Aránzazu Valverde ◽  
Elisabete Machado ◽  
Juan-Carlos Galán ◽  
...  

ABSTRACT This study analyzes the diversity of In60, a class 1 integron bearing CR1 and containing bla CTX-M-9, and its association with Tn402, Tn21, and classical conjugative plasmids among 45 CTX-M-9-producing clinical strains (41 Escherichia coli strains, 2 Klebsiella pneumoniae strains, 1 Salmonella enterica strain, and 1 Enterobacter cloacae strain). Forty-five patients in a Spanish tertiary care hospital were studied (1996 to 2003). The diversity of In60 and association of In60 with Tn402 or mercury resistance transposons were investigated by overlapping PCR assays and/or hybridization. Plasmid characterization included comparison of restriction fragment length polymorphism patterns and determination of incompatibility group by PCR-based replicon typing, sequencing, and hybridization. CTX-M-9 plasmids belonged to IncHI2 (n = 26), IncP-1α (n = 10), IncFI (n = 4), and IncI (n = 1) groups. Genetic platforms containing bla CTX-M-9 were classified in six types in relation to the In60 backbone and in eight subtypes in relation to Tn402 derivatives. They were associated with Tn21 sequences when located in IncP-1α or IncHI2 plasmids. Our study identified bla CTX-M-9 in a high diversity of CR1-bearing class 1 integrons linked to different Tn402 derivatives, often to Tn21, highlighting the role of recombination events in the evolution of antibiotic resistance plasmids. The presence of bla CTX-M-9 on broad-host-range IncP-1α plasmids might contribute to its dissemination to hosts that were not members of the family Enterobacteriaceae.


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