Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Integrons”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2005

Class 1 integrons in Pseudomonas aeruginosa isolates from clinical settings in Amazon region, Brazil.

A hundred and six Pseudomonas aeruginosa isolates from clinical cases were screened using PCR for the presence of integrons and associated resistance gene cassettes. Forty-four isolates harboured class 1 integrons (41.5%), of which 29 isolates (66%) also carried gene cassettes. The aacA gene was most frequently found within class 1 integrons (69%), followed by blaOXA family genes (52%). From class 1 integron-positive strains, we detected a total of 15 isolates (34%) carrying no gene cassettes. Restriction fragment-length polymorphism analysis of the integrons variable region revealed some identical structures, as well as distinct profiles indicating heterogeneity among these cassette regions. Multiresistance was observed in 71% of isolates, nevertheless no strong correlation was observed between integron presence and multiresistance. This is the first report showing class 1 integron prevalence and gene cassette content in P. aeruginosa isolates from clinical settings in the Brazilian Amazon.

Brazil↗
PubMed2004

Analysis of integrons in human isolates of Salmonella enterica serovar typhimurium isolated in the Slovak Republic.

About 110 sporadic, epidemiologically unrelated Salmonella enterica serovar typhimurium strains isolated in the Slovak Republic were analyzed for the presence of integrons. Of these 110 examined strains, 47 were of definitive phage type DT104 and 63 were strains of various phage type, RDNC and untypeable, designated here as non-DT104 strains. All isolates were also tested for antimicrobial resistance to 10 antibiotics as well as for the presence of virulence plasmid. Of 63 non-DT104 strains, 15 isolates were multiple-resistant, independently from phage type, other strains were resistant to one, two or three drugs. Resistance to ampicillin, streptomycin, tetracycline and sulfisoxazole was most frequently observed. Among the DT104 isolates up 65.9% exhibited characteristic pentaresistance--ACSSuT phenotype. The integron content was studied in PCR experiments using a 5'-CS/3'-CS primer pair. Fourteen non-DT104 strains, independently from phage type, were found to carry integrons with amplicons 650-1900 bp in size. Thirty-six DT104 strains contained integrons of 1000 and 1200 bp and 31 of they exhibited the ACSSuT phenotype. No integron was found in 10 DT104 strains, which included strains mostly resistant only to streptomycin, tetracycline and sulfisoxazole. The majority of non-DT104 strains did not possess any integrons. Our findings show the widespread existence of both resistant and multiple-resistant epidemiologically unrelated Salmonella typhimurium strains and suggest that integrons contribute to this antimicrobial resistance. The presence of 90-kb virulence plasmid in the 54 non-DT104 and in the all DT104 strains was found.

Anti-Bacterial Agents↗
PubMed2006

Class 2 integron-associated antibiotic resistance in Shigella sonnei isolates in Dakar, Senegal.

Forty-three Shigella sonnei isolates from adult patients with diarrhoea in Dakar were analysed for the presence of integrons. Isolates were resistant to sulphamethoxazole, trimethoprim, tetracycline, streptomycin and spectinomycin. A high prevalence of class 2 integrons (93%) was found. These integrons showed three distinct structures: a class 2 integron, part of the Tn7 family and its derivatives, carrying four cassettes in the order dfrA1-sat-aadA1-orfX; a truncated class 2 integron, without orfX; and a third type ca. 4 kb in size. These class 2 integrons probably play a role in the spread of multiresistance in S. sonnei isolates. To our knowledge, this is the first description of class 2 integrons in S. sonnei isolated in sub-Saharan Africa.

Adult↗
PubMed2006

Molecular differentiation of common promoters in Salmonella class 1 integrons.

The integron is a mobile gene element which harbors antibiotic-resistance gene cassettes capable of site-specific integration. Among the four known types of integrons, the class 1 integron has been associated with multidrug-resistance in pathogenic bacteria. These gene cassettes have been the focus of a series of studies. The gene cassettes share a common promoter, and their expression levels are affected not only by their proximity to the promoter, but also by the strength (weak, hybrid and strong) of the common promoter, P1, as well as the presence of the additional promoter, P2. In this study, we developed molecular methods for the differentiation of promoter structures using PCR, restriction enzyme analysis, and polyacrylamide gel electrophoresis, and have applied them to the characterization of class 1 integrons in 33 non-typhoidal Salmonella serotypes in Korea. Class 1 integrons were detected in four serotypes: S. Derby (SD), S. Istanbul (SI), S. Paratyphi B (SPB), and S. Livingstone (SL), and the amplicon sizes were 1.0 Kb (SD, SI and SPB) and 2.0 Kb (SL). All of the 1.0 kb amplicons harbored gene cassettes (aadA1 or aadA2), but the 2.0 kb amplicon harbored three (dhfrXII-orfF-aadA2) gene cassettes, which conferred streptomycin/spectinomycin (aadA) and trimethoprim (dhfr) resistances. Our promoter structure study revealed three types of promoters; strong P1 (SD), weak P1 (SPB and SL), and weak P1+P2 (SI). In conclusion, the class 1 integrons were detected in Korean NTS, and their promoter structures were found to be variable. Therefore, our methods may prove helpful in terms of our understanding of molecular diversity, as well as the transmission of class 1 integrons and phenotype-genotype relationships in antibiotic-resistance.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Structure and function of integrons].

Integrons are genetic elements known for their role in the acquisition and expression of genes conferring antibiotic resistance. Integrons have an integrase gene (intI), an attachment site (attI), into which individual resistance genes are inserted and a promotor sequence (Pant), allowing expression of resistance genes (cassette-associated genes), which do not have promotors. Integrase recognizes 59-be, a specific sequence in certain resistance genes, which is captured by recombination at the attI attachment site. The fragment intI - attI is highly conserved in all integrons and is called 59 -CS. Integrons have been classified according to the sequence of their integrase and the ones most frequently detected in isolated clinical strains belong to Class I. Class I integrons contain the 59 -CS region followed by gene cassettes in a variable region and finally, a conserved region known as 39 -CS containing two genes, the quaternary ammonium resistance gene (qacEDI) and the sulphonamide resistance gene (sul1); both genes are fixed in this structure. Accordingly, the structure of a Class 1 integron would be IntI - attI [R11 R21.] - qacED1 - sul1. Integrons are probably not mobile, but they are often found in transposons within conjunctive plasmids, which assures their mobility, as can be seen by their wide diffusion among bacteria.

Drug Resistance, Microbial↗
PubMed2003

Integron-mediated antibiotic multiresistance in Acinetobacter baumannii clinical isolates from Spain.

OBJECTIVE: To determine whether non-epidemiologically related, antibiotic-resistant isolates of Acinetobacter baumannii from different geographical origins possess common type 1 integrons. METHODS: The epidemiologic relationships between seven A. baumannii strains recovered from different Spanish hospitals were established by pulsed-field gel electrophoresis, the presence of integrons being determined by PCR and DNA sequencing. RESULTS: Integron analysis showed the presence of four different integrons, containing six different known genes (aacC1, aacA4, aadA1, aadB, oxa21 and oxa37) plus an ORF. It was found that the same integron was present in different unrelated strains and that related strains could have different integrons. CONCLUSION: These results show the potential risk of integron dissemination among different strains of A. baumannii.

Acinetobacter Infections↗
PubMed2002

Multidrug resistance among Enterobacteriaceae is strongly associated with the presence of integrons and is independent of species or isolate origin.

This study investigated the extent to which multidrug resistance (MDR) among Enterobacteriaceae is related to DNA elements called "integrons," whether the relationship is species dependent or origin dependent, and which resistance patterns are associated with integrons. Analysis of 867 nonrepeat isolates comprising 8 species and originating from the community and 23 European hospitals showed a significant relation between MDR and integrons, independent of species or origin. Although resistance to each tested antimicrobial agent was significantly associated with integrons, only resistance to sulfamethoxazole, cotrimoxazole, gentamicin, tobramycin, ampicillin, piperacillin, and cefuroxime predicted the presence of integrons. Combined resistance to both ampicillin and sulfamethoxazole-trimethoprim was the starting point for the development of resistance to additional beta-lactams, aminoglycosides, cephalosporins, and ciprofloxacin, a development paralleled by an increasing prevalence of integrons. The acquisition of resistance genes is not random, and the transfer of integron-carrying elements plays a dominant role in the development of MDR by Enterobacteriaceae.

Anti-Bacterial Agents↗
PubMed2004

Integron-associated antibiotic resistance in enteroaggregative and enteroinvasive Escherichia coli.

Ten enteroinvasive (EIEC) and 25 enteroaggregative (EaggEC) E. coli strains isolated from Senegalese patients were analyzed for their integron content. All strains were resistant to at least two antibiotics. Four EIEC and 15 EaggEC were found to carry a class 1 integron. An identical integron carrying a single dfrA5 cassette, conferring resistance to trimethoprim, was identified in all four EIEC strains. Five EaggEC strains harbored an integron with a single cassette, dfrA7, while the remaining 10 strains carried two integrons, one with a single cassette, aadA1a conferring resistance to streptomycin and spectinomycin, and the second one bearing two cassettes, dfrA13 and oxa5, the later being a beta-lactam resistance cassette. The presence of these integrons is worrying, because trimethoprim is largely used for diarrheal disease therapy in Africa. Thus, the presence of integrons in diarrheagenic strains is of public health importance because a limited number of antibiotics are available in developing countries.

Chromosome Mapping↗
PubMed2005

Antimicrobial resistance and class 1 integrons in pathogenic Escherichia coli from dairy farms.

The goal of this study was to assess the prevalence of antimicrobial resistance and class 1 integrons, including integron-associated genes, in 24 Escherichia coli isolates from dairy farms. Escherichia coli isolates (n = 14) from dairy cows with mastitis (ECDM), Shiga toxin-producing (STEC) O157:H7 from cull dairy cow fecal samples (n = 9) and bulk tank milk (n = 1) were evaluated for sensitivity to 19 antimicrobial agents used commonly in human and/or veterinary medicine. Multiplex PCR was used to determine presence of genes associated with class 1 integrons (intI1, qacEDelta1, and sulI1). Class 1 integrons were found only in eight of 10 isolates (one STEC O157:H7 and seven ECDM) that demonstrated antimicrobial resistance, and seven of these were resistant to two or more antimicrobial agents. Eight of 10 STEC O157:H7 and six of 14 ECDM were susceptible to all commonly used antibiotics. Five ECDM demonstrated multiple resistances to four or more antibiotics. Most of the 24 isolates examined exhibited resistance against sulfamethoxazole, followed by streptomycin and tetracycline. STEC O157:H7 strains had less prevalence of antibiotic resistance and integron carriage than ECDM. The multiplex PCR method developed for detection of intI1, qacEDelta1, and sulI1 can be used routinely for monitoring presence of these genes. Class 1 integrons were found in eight of 10 E. coli strains that demonstrated antimicrobial resistance; seven of these were resistant to two or more antibiotics. It appears that integrons played a role in the incidence of antimicrobial resistance of the strains used in this study.

Animals↗
PubMed2006

Characterization of acquired beta-lactamases and their genetic support in multidrug-resistant Pseudomonas aeruginosa isolates in Taiwan: the prevalence of unusual integrons.

OBJECTIVES: The present study was conducted to investigate acquired beta-lactamases and their genetic support in 26 Pseudomonas aeruginosa isolates that were resistant to nearly all antipseudomonal drugs from six medical centres in Taiwan. METHODS: Acquired beta-lactamases and their genetic support were determined by PCR-based strategies. RESULTS: Four and 16 of the 26 isolates were found to produce VIM-2 and VIM-3 metallo-beta-lactamases (MBLs), respectively, and 1, 1 and 2 isolates produced OXA-17, OXA-10 and PSE-1, respectively. These bla genes are all in class 1 integrons that are probably chromosomally located. The bla(VIM-3)-containing integron, with a deletion between int1 and the bla(VIM-3) structural gene, has six gene cassettes, bla(VIM-3), a probable fosfomycin resistance determinant, aacA4, aacA4, aadB and aacA4. The bla(VIM-2)-containing integron, without detectable 5'-conserved segment, contains four genes cassettes (aacA7-bla(VIM-2)-dhfr-aacA5) and is ended by tniC. The bla(OXA-10)-containing integron includes a catB3 cassette and a fused gene cassette, which is made up of bla(OXA-17) and a novel streptomycin-spectinomycin gene, designated aadA15. The bla(OXA-17)-containing integron has three gene cassettes (aacA4-catB2-bla(OXA-17)) but the 59-base element of the bla(OXA-17) cassette is interrupted by a putative transposase gene. The bla(PSE-1)-containing integron has three gene cassettes, aacA4, an aadA3-related gene designated aadA3b and bla(PSE-1). PFGE revealed genetic diversity among the multidrug-resistant isolates from different hospitals. CONCLUSIONS: This study demonstrated the high prevalence of VIM-type MBLs and the presence of unusual bla-encoding integrons in multidrug-resistant P. aeruginosa isolates in Taiwan. The spread of bla(VIM-2)-related genes by horizontal transfer might have occurred.

Anti-Bacterial Agents↗
PubMed2004

Diversity of aminoglycoside-resistance genes and their association with class 1 integrons among strains of pan-European Acinetobacter baumannii clones.

The purpose of the present study was to investigate the diversity of the genes encoding aminoglycoside-modifying enzymes and their association with class 1 integrons in three pan-European clones of Acinetobacter baumannii. The study collection included 106 multidrug-resistant strains previously allocated to clone I (n = 56), clone II (n = 36) and clone III (n = 6) and a heterogeneous group of other strains (n = 8), using AFLP fingerprinting and ribotyping. The strains were from hospitals of the Czech Republic (n = 70; collected 1991-2001) and 12 other European countries (n = 36; 1982-1998). Using PCR, at least one of the following aminoglycoside-resistance genes was detected in 101 (95 %) strains: aphA1 (n = 76), aacC1 (n = 68), aadA1 (n = 68), aphA6 (n = 55), aadB (n = 31), aacC2 (n = 7) and aacA4 (n = 3). A combination of two to five different resistance genes was observed in 89 strains (84 %), with a total of 12 different combinations. PCR mapping revealed that aacC1, aadA1 and aacA4 were each associated with a class 1 integron, as was the case with aadB for six strains of clone III. Six different class 1 integron variable regions were detected in 78 strains (74 %), with two predominant regions (2.5 and 3.0 kb) in two sets of 34 strains each. The 3.0 kb region contained five gene cassettes (aacC1, orfX, orfX, orfX', aadA1) and differed from the 2.5 bp region only by one additional orfX cassette. These two integron regions were confined to clones I and II and were found in strains isolated in seven countries between 1982 and 2001. The clone III strains were homogeneous both in resistance genes and in integron variable regions, whereas clones I and II showed a remarkable intraclonal diversity of these properties, with no clear-cut difference between the two clones. Yet, within the Czech clone I and II strains, the diversity of resistance genes and integron structures was limited as compared to those from other countries. The occurrence of identical resistance genes, gene combinations and class 1 integrons associated with these genes in clonally distinct strains indicates that horizontal gene transfer plays a major role in the dissemination of aminoglycoside resistance in A. baumannii.

Acinetobacter baumannii↗
PubMed2003

Class 1 integron-borne gene cassettes in multidrug-resistant Yersinia enterocolitica strains of different phenotypic and genetic types.

Seventy nine strains of Yersinia enterocolitica resistant to one or more antimicrobials were analyzed for integrons. Only class 1 sul1 integrons containing aadA1a (28 strains), aadA1a-dfr1-sat1 (2 strains), and dfr1-aadA1a (1 strain) gene cassettes were found. The first two types were found in clinical isolates belonging to serotype O:3, biotypes 2 to 4, and eight combined ribotypes, and the third was found in the reference strain, CECT4054 (O:8). All screened resistance markers were found in strains with and without integrons (except for chloramphenicol resistance, encoded by catA1 gene, which was only present in strains with integrons), but in different resistance profiles (R profiles). A profile (ampicillin, streptomycin, sulfadiazine, and trimethoprim resistance, encoded by the tem1, aadA1a, sul1, and dfr1 genes, respectively) was found in strains, with and without integrons. Integrons and some of the resistance genes are located on plasmids with sizes ranging between 65 and 140 kb. This is the first report of class 1 integrons in Y. enterocolitica.

Drug Resistance↗
PubMed2005

[Class 1 integrons among Salmonella enterica isolates producing different types of beta-lactamases from the health region of Tortosa (Spain)].

OBJECTIVE: To assess the frequency of class 1 integrons among isolates of Salmonella enterica producing different types of beta-lactamases from the health region of Tortosa, and to attempt to establish the resistance genes located within their variable regions. METHODS: The presence of class 1 integrons and of aadA1, aadA2, dfrA1, tem-1, oxa-1 and pse-1 resistance genes within their variable regions was investigated by PCR in 100 ampicillin-resistant isolates of S. enterica (30 S. enteritidis, 56 S. Typhimurium and 14 from other serotypes) consecutively recovered in our laboratory between 2000 and 2001. Beta-lactamases were characterized by isoelectric focusing and PCR. RESULTS: a) 6/57 TEM-1 producing isolates carried integrons: 1 S. ser Panama, 2 S. ser Enteritidis and 1 S. ser Typhimurium (1600 pb/aadA1-dfrA1); 1 S. ser Panama (1600 pb/aadA2-dfrA1); 1 S. ser Grumpensis (1500 pb 1 1700 pb; aadA2 and ??) b) All OXA-1 producing isolates (20 S. ser Typhimurium) bore an integron of 2000 pb/aadA1-oxa-1; c) All PSE-1 producing isolates (22 S. ser Typhimurium, most of them 104 phage type, and 1 S. enterica immobile [4,12:-:-]) harbored 2 integrons (1000 pb/aadA1 and 1,00 pb/pse-1). CONCLUSION: The presence of class 1 integrons carrying oxa-1 or pse-1 resistance genes in all the OXA-1-producing and PSE-1-producing isolates investigated could have contributed to their spread and explain the increase in frequency of multiresistant S. ser Typhimurium isolates harboring these enzymes seen in the health region of Tortosa. In addition, we report the first isolate of S. ser enterica serotype Grumpensis harboring integrons.

Drug Resistance, Bacterial↗
PubMed2006

Shigella sonnei biotype G carrying class 2 integrons in southern Italy: a retrospective typing study by pulsed field gel electrophoresis.

BACKGROUND: Emergence and global dissemination of multiresistant strains of enteric pathogens is a very concerning problem from both epidemiological and Public Health points of view. Shigella sonnei is the serogroup of Shigella most frequently responsible for sporadic and epidemic enteritis in developed countries. The dissemination is associated most often to human to human transmission, but foodborne episodes have also been described. In recent years the circulation of multiresistant strains of S. sonnei biotype g carrying a class 2 integron has been reported in many countries worldwide. In southern Italy a strain with similar properties has been responsible for a large community outbreak occurred in 2003 in Palermo, Sicily. The objective of this study was to date the emergence of the biotype g strain carrying the class 2 integron in southern Italy and to evaluate the genetic heterogeneity of biotype g S. sonnei isolated throughout an extended interval of time. METHODS: A total of 31 clinical isolates of S. sonnei biotype g identified in southern Italy during the years 1971-2000 were studied. The strains were identified at the serogroup level, characterized by biochemical tests and submitted to antimicrobial susceptibility testing. Molecular typing was performed by pulsed field gel electrophoresis (PFGE) after digestion of DNA by XbaI. Carriage of class 2 integrons was investigated by polymerase chain reaction (PCR) with specific primers and confirmed by restriction endonuclease analysis of amplicons. RESULTS: The 15 isolates of S. sonnei biotype g identified in the decade 1971-1980 showed highly heterogeneous drug resistance profiles and pulsotypes. None of the isolates was simultaneous resistant to streptomycin and trimethoprim and none was class 2 integron positive. On the contrary, this resistance phenotype and class 2 integron carriage were very common among the 16 strains of biotype g identified in the following two decades. Moreover, all the more recent isolates, but one, showed closely related pulsotypes. CONCLUSION: Although our findings refer to a limited geographic area, they provide a snapshot of integron acquisition by an enteric pathogen responsible for several outbreaks in the years 2001-2003 in Italy. Molecular typing, indeed, suggests that the emergence of biotype g class 2 integron carrying S. sonnei in southern Italy should be backdated to at least the late 1980s. In the following decades, the circulation of biotype g appears to be sustained by multiresistant highly related strains. Similar trend are described in several countries, but the questions about mechanism of emergence and worldwide spread of this pathogen remain open.

Bacterial Typing Techniques↗
PubMed2006

[Detection of class I integron and its relation to antimicrobial resistance of Shigella flexneri in children].

OBJECTIVE: To investigate class I integron of Shigella flexneri, its prevalence in children, and its relation to bacterial resistance to antimicrobial agents. METHODS: Totally 51 strains of Shigella flexneri were isolated from fecal samples of children suffering from bacterial diarrhea seen between June 2004 and November 2004 at Children's Hospital of Fudan University. Polymerase chain reaction (PCR) was employed to amplify various integron markers, including intI1, gene cassette region and 3' conserved region of class I intrgron; susceptibility of Shigella flexneri strains to 7 antimicrobial agents was determined by K-B (Kriby-Bauer) method. RESULTS: Forty-six strains of Shigella flexneri had intI gene with a positive rate of 90.2% (46/51); 24 strains of Shigella flexneri were positive for qacEDelta1-sul1, the positive rate was 47.1% (24/51); proportion of the isolates positive for all the three regions of class I integron was 43.1% (22/51); 46 strains of intI positive Shigella flexneri were all positive for ant (3'')-I. Among 46 strains of intI positive isolates, proportions of the isolates positive and negative for qacEDelta1-sul1 were 47.8% (22/46) and 52.2% (24/46), respectively. In the class I integron positive Shigella flexneri, the resistance rates of ampicillin (chi(2) = 10.13, P < 0.01) and chloramphenicol (chi(2) = 19.97, P < 0.01) were significantly higher than those in the class I integron-negative group. CONCLUSIONS: Class I integron was detected in 90.2% of Shigella flexneri in children; carriage of class I integron is related to antimicrobial resistance of Shigella flexneri.

Anti-Bacterial Agents↗
PubMed1993

The partial 3'-conserved segment duplications in the integrons In6 from pSa and In7 from pDGO100 have a common origin.

Integrons are genetic elements which are capable of acquiring genes by site-specific recombination. The most common integron structure consists of two conserved segments flanking a variable region where many different antibiotic resistance genes have been found. The integrons In6 and In7, present in the plasmids pSa and pDGO100, respectively, are unusual in that they include a duplication of the sulI gene which is located within the integron 3'-conserved segment. To further investigate the structure of these integrons, the DNA sequence of the segment located between the two sulI genes was determined. In In7 this segment is 2822 bases long and includes a trimethoprim resistance gene, dhfrX, at one end. The corresponding region in In6 is 4.5 kb and is nearly identical to the In7 segment over the first 2105 bases. In the region unique to In6, a cat gene, conferring chloramphenicol resistance, has replaced the dhfrX gene of In7. This location thus represents a second variable region where different antibiotic resistance genes are found, but the way in which genes become associated with this second variable region is not known. The overall similarity of the structures of In6 and In7 suggests that the additional DNA segments found in these integrons have a common origin, and a possible mechanism for the origin of integrons with partial 3'-conserved segment duplications is presented.

Amino Acid Sequence↗
PubMed2001

Integrons: natural tools for bacterial genome evolution.

Integrons were first identified as the primary mechanism for antibiotic resistance gene capture and dissemination among Gram-negative bacteria. More recently, their role in genome evolution has been extended with the discovery of larger integron structures, the super-integrons, as genuine components of the genomes of many species throughout the gamma-proteobacterial radiation. The functional platforms of these integrons appear to be sedentary, whereas their gene cassette contents are highly variable. Nevertheless, the gene cassettes for which an activity has been experimentally demonstrated encode proteins related to simple adaptive functions and their recruitment is seen as providing the bacterial host with a selective advantage. The widespread occurrence of the integron system among Gram-negative bacteria is discussed, with special focus on the super-integrons. Some of the adaptive functions encoded by these genes are also reviewed, and implications of integron-mediated genome evolution in the emergence of novel bacterial species are highlighted.

DNA Transposable Elements↗
PubMed2001

Discovery and distribution of super-integrons among pseudomonads.

Until recently, integrons (systems for acquisition and expression of new genetic materials) have been associated generally with antibiotic resistance gene cassettes. The discovery of 'super-integrons' in Vibrionaceae suggests a greater impact of this gene acquisition mechanism on bacterial genome evolution than initially believed. Super-integrons may contain more than 100 gene cassettes and may encode other determinants, including biochemical functions or virulence factors. Here, we report the genetic organization of a super-integron from Pseudomonas alcaligenes ATCC 55044. This is the first evidence of a super-integron in a non-pathogenic bacterium, one which is widely distributed in a great number of ecological niches such as soil and aquatic habitats. Here, the sequence composition, open reading frame (ORF) content and organization of In55044 are described and found to have features intermediate between the multidrug-resistant integrons and the Vibrio cholerae super-integron. Similar structures are inferred to be present in several Pseudomonas species, based on polymerase chain reaction (PCR) experiments.

Amino Acid Sequence↗