Role Of Integrons Research Articles

Molecular detection of Class 1, 2, and 3 integrons in hypervirulent and classic Klebsiella pneumoniae isolates: A cross-sectional study.

The "hypervirulent" variant of Klebsiella pneumoniae (hvKp) is an emerging pathogen that cause life-threatening infection. The present study was conducted to identify the prevalence of hvKp and to investigate the presence class 1, 2, and 3 integrons in these isolates. A cross-sectional study was conducted at three teaching hospitals, Ahvaz, South-west of Iran, from January 1, 2019 to December 31, 2020. Samples were collected from inpatients and included only the first samples collected from each patient. K. pneumoniae strains were isolated from different specimens using biochemical test and confirmed by targeting 16S-23S rDNA internal transcribed spacer. HvKp isolates were recovered using string test and were further characterized by detection virulence-associated genes (rmpA, iucA, and magA). Antibiotic susceptibility patterns of isolates were determined using the disc diffusion method. Isolates were screened for presence the integron genes (intI, intII, and intIII) and repetitive element sequence-based polymerase chain reaction (PCR) performed to determine strain relatedness. SPSS version 22 was used for the data analysis. Seventy-one (77%) of isolates showed multidrug-resistant (MDR) phenotype. HvKP accounted for 14% (13/92) of cKp isolated from blood (46%) and urinary tract infection (38%), and the great majority of them (61.5%; 8/13) exhibited MDR phenotype. Using the PCR assay, 29 of 92 isolates (31.5%) were found to have positive results for the presence of IntI. Three of the IntI-positive strains were hvKP. Class 2 integron was present in 8/92 cKp isolates. Integron Class 2 was found to coexist with Class 1 integron in 3/8 isolates. All integron-positive isolates (IntI and/or IntII) were resistant to at least three different classes of antibiotics and showed MDR phenotype. No Class 3 integrons were detected among the isolates. The results of our study revealed that considering the role of integrons in facilitating the acquisition and dissemination of resistance genes among bacteria, monitoring the emergence of hvKp, emphasizing on the mechanism of antimicrobial resistance, can prevent from the spread of carbapenemase-producing hvKp strains.

Role of Integrons 1 and 2 in Proteus spp. and Evaluation of Some Antibiotic's Resistance Genes

Role of Integrons 1 and 2 in Proteus spp. and Evaluation of Some Antibiotic's Resistance Genes

Investigation of antimicrobial susceptibility, class I, II, and III integrons among clinical isolates of Pseudomonas aeruginosa from hospitalized burn patients in Southern Iran

Abstract Introduction Burn infection due to Pseudomonas aeruginosa poses a considerable challenge in terms of graft loss, systemic sepsis, prolonged hospital stays, and even enhanced mortality. The aim of this study was to consider the susceptibility pattern to antibiotics and occurrence of class I, II, and III integrons in P. aeruginosa isolated from hospitalized burn patients. Materials and Methods A cross-sectional study was performed on 70 P. aeruginosa isolates obtained from blood, wounds, biopsy, and sputum samples from burn patients between January 2020 and March 2021 from different wards of a teaching hospital in Ahvaz, Iran. Results Antimicrobial susceptibility pattern was performed using the disk diffusion method. Also, PCR was carried out for the detection of intI1, intI2 and intI3 genes. Among the 70 P. aeruginosa isolates, 34 (48.6%) isolates were obtained from females and 36 (51.4%) isolates from males. PCR amplification revealed that 51.4% isolates (36/70) had intI1, 30% isolates (21/70) had intI2, and 12.9% isolates (9/70) had both genes. However, the intI3 gene was not detected in any isolates. Furthermore, there is no important association between resistance to antibiotics and the presence of intI genes. Conclusion According to our results, there were no statistically significant differences among resistance to antibiotics and the presence of intI and intI1 genes. However, the surveillance of patterns of antibiotic resistance and investigation into the role of integrons in controlling the scattering of antibiotic-resistant genes are recommended.

Resistance to Antibiotics in Thermophilic Campylobacters.

Campylobacter jejuni (C. jejuni) is one of the most frequent causes of bacterial enterocolitis globally. The disease in human is usually self-limiting, but when complications arise antibiotic therapy is required at a time when resistance to antibiotics is increasing worldwide. Mechanisms of antibiotic resistance in bacteria are diverse depending on antibiotic type and usage and include: enzymatic destruction or drug inactivation; alteration of the target enzyme; alteration of cell membrane permeability; alteration of ribosome structure and alteration of the metabolic pathway(s). Resistance of Campylobacter spp. to antibiotics, especially fluoroquinolones is now a major public health problem in developed and developing countries. In this review the mechanisms of resistance to fluoroquinolones, macrolides, tetracycline, aminoglycoside and the role of integrons in resistance of Campylobacter (especially at the molecular level) are discussed, as well as the mechanisms of resistance to β-lactam antibiotics, sulphonamides and trimethoprim. Multiple drug resistance is an increasing problem for treatment of campylobacter infections and emergence of resistant strains and resistance are important One Health issues.

Integron and its role in antimicrobial resistance: A literature review on some bacterial pathogens.

In recent years, different acquired resistance mechanisms, including transposons, bacteriophages, plasmids, and integrons have been identified as involved in the spread of resistance genes in bacteria. The role of integrons as mobile genetic elements playing a central role in antibiotic resistance has been well studied and documented. Integrons are the ancient structures that mediate the evolution of bacteria by acquiring, storing, disposing, and resorting to the reading frameworks in gene cassettes. The term integron describes a large family of genetic elements, all of which are able to capture gene cassettes. Integrons were classified into three important classes based on integrase intI gene sequence. Integrons can carry and spread the antibiotic resistance genes among bacteria and are among the most significant routes of distribution of resistance genes via horizontal transfer. All integrons have three essential core features. The first feature is intI, the second one is an integron-associated recombination site, attI, and an integron-associated promoter, Pc, is the last feature. Among them, the class 1 integron is a major player in the dissemination of antibiotic resistance genes across pathogens and commensals. Various classes of integrons possessing a wide variety of gene cassettes are distributed in bacteria throughout the world. This review thus focuses on the distribution of integrons among important bacteria.

Role of integrons in the proliferation of multiple drug resistance in selected bacteria occurring in poultry production

ABSTRACT1. The increase in microbial resistance, and in particular multiple drug resistance (MDR), is an increasing threat to public health. The uncontrolled use of antibiotics and antibacterial chemotherapeutics in the poultry industry, especially in concentrations too low to cause inhibition, and the occurrence of residues in feed and in the environment play a significant role in the development of resistance among zoonotic food-borne microorganisms.2. Determining the presence and transmission methods of resistance in bacteria is crucial for tracking and preventing antibiotic resistance. Horizontal transfer of genetic elements responsible for drug resistance is considered to be the main mechanism for the spread of antibiotic resistance.3. Of the many well-known genetic elements responsible for horizontal gene transfer, integrons are among the most important factors contributing to multiple drug resistance. The mechanism of bacterial drug resistance acquisition through integrons is one of the essential elements of MDR prevention in animal production.

Frequency of class I and II integrons in the clinical isolates of Pseudomonas aeruginosa with multidrug resistance in Shahrekord teaching hospitals and Isfahan Shahid Chamran hospital during 2016-2017

Background and aims: Increasing the prevalence of nosocomial infections by multidrug resistant (MDR) Pseudomonas aeruginosa has severely challenged the choice of treatment and led to an increased mortality rate. Thus, this study investigated the frequency of class I and II integrons and its association with MDR. Materials and Methods: A total of 175 P. aeruginosa isolates were collected from Shahrekord teaching hospitals and Isfahan Shahid Chamran hospital during 12 months (from April 2008 to March 2009). Antibiotic susceptibility was determined by disc diffusion according to the Clinical and Laboratory Standards Institute (CLSI) Antimicrobial Susceptibility Testing. The E-test strips of imipenem, ciprofloxacin, and amikacin were used to identify the minimum inhibitory concentration and MDR bacteria. Finally, the frequency of class I and II integrons genes was evaluated by using the polymerase chain reaction test. Results: The highest antibiotic resistance and the highest susceptibility belonged to meropenem (86.9%) and polymyxin B (96.0%) by disc diffusion, respectively. By the E-test, the highest and lowest resistance rates were reported for imipenem (97.2%) and ciprofloxacin (86.8%), respectively. The frequency of MDR strains was 82.3% as well. The frequency of class I and II integrons was 57.7% and 17.7% in all P. aeruginosa isolates, as well as 68.1%and 21.5% in the MDR isolates, respectively. There was also a significant correlation between I and II integrons and MDR. Conclusion: Overall, the resistance to different antibiotics and the frequency of MDR strains among the studied P. aeruginosa isolates were very high. There was also a significant correlation between integrons and multidrug resistance. Regarding the role of integrons in the transfer of drug-resistant genes and the development of MDR strains, the use of appropriate diet and accurate determination of the susceptibility pattern of P. aeruginosa isolates are considered necessary.

Molecular Analysis and Integron Carriage of Mupirocin-Resistant Staphylococcus aureus Strains Isolated from Burn Wound Infections, Tehran, Iran

Background: The prevalence of wound infections associated with multidrug-resistant Staphylococcus aureus (S. aureus) strains among burns patients has tremendously increased. Recently, the role of integrons as a key system involved in spreading multi-drug resistance has been well documented. Objectives: To investigate the prevalence of integrons, antimicrobial resistance pattern, and S. aureus protein A (spa) typing of the mupirocin-resistant S. aureus (MRSA) strains obtained from a referral burns hospital in Tehran, Iran. Methods: This study was performed during January 2017 to April 2018 on 64 MRSA isolates gathered from burns patients. The isolates were examined for susceptibility to antimicrobial agents. The integrase-encoding gene was detected by conventional polymerase chain reaction (PCR). Integrase-positive strains were evaluated for the determination of integron classes by using PCR-restriction fragment length polymorphism assay, and genotyping was performed by spa typing. Results: Out of 64 MRSA strains, 24 (37.5%) and 40 (62.5%) isolates carried high-level and low-level resistance, respectively. The findings revealed that the entire isolates were MRSA. They belonged to six different spa types including t860 (40.6%), t790 (21.8%), t037 (17.2%), t064 (17.2%), t008 (1.6%), and t631 (1.6%). Class 1 and 2 integrons were found in 59.4% and 17.2% of the isolates, respectively, and 4 (6.2%) isolates were observed to carry class 1 and 2 integrons simultaneously. Conclusions: Precise epidemiological monitoring of integrons is required to prevent mupirocin resistance dissemination in MRSA strains.

Resistance integrons; A Mini review.

Integrons are a segment of dsDNA that play a major role in bacterial adaptation and evolution. These genetic determinants are known by the presence of three necessary apparatuses: an integrase (intI gene), Pc (a promoter) and attI (a recombination site). These elements are able to acquire gene cassettes, which can carry antibiotic resistance factors, by site-specific recombination mechanism. The most common types of resistance integrons are class I (Tn402 derivatives), followed by class II and III. In recent years, the role of integrons as an important factor in the transmission and spread of resistance factors has been considered. Therefore, the ongoing threats posed by integrons require an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons. It shows how antibiotics use selected particular integrons from the environmental pool, so that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens.

Role of integrons, plasmids and SXT elements in multidrug resistance of Vibrio cholerae and Providencia vermicola obtained from a clinical isolate of diarrhea.

The isolates of Vibrio cholerae and Providencia vermicola obtained from a diarrheal patient were investigated for genetic elements governing their drug resistance phenotypes. Out of 14 antibiotics tested, V. cholerae Vc IDH02365 isolate showed resistance to nine antibiotics, while P. vermicola Pv NBA2365 was found to be resistant to all the antibiotics except polymyxin B. Though SXT integrase was depicted in both the bacteria, class 1 integron was found to be associated only with Pv NBA2365. Integrons in Pv NBA2365 conferred resistance to β-lactams, aminoglycosides, and trimethoprim. Pv NBA2365 carried two transformable plasmids imparting distinct antibiotic resistance traits to their Escherichia coli transformants. In rabbit ileal loop assays, Pv NBA2365 did not show any fluid accumulation (FA) in contrast with Vc IDH02365 that showed high FA. To the best of our knowledge, this is the first report of a highly drug resistant P. vermicola and additionally co-existence of multidrug resistant V. cholerae and P. vermicola. Both the microbes appeared to possess a wide array of mobile genetic elements for a large spectrum of antimicrobial agents, some of which are being used in the treatment of acute diarrhea.

Frequency of class 1 integron in Escherichia coli strains isolated from patients with urinary tract infections in north of iran.

Background:Due to the importance of antibiotic resistance in E.coli and the possible role of integrons in creating of resistance, this study was performed to survey of class 1 integron in E. coli strains and their resistance to three routinely used antibiotics.Methods:In this cross-sectional study, 100 strains of E. coli were isolated from patients with Urinary tract infection. After diagnosis of bacteria, genomes were extracted. Then, presence of integron class 1 was evaluated by using PCR. Antibiotic susceptibility testing method, the micro dilution broth was performed according to the standard CLSI2010. Data were analyzed using SPSS16 software.Result:Out of the total number of 100 E. coli cases, 22 cases (22%) had class 1 integron. Resistance against cotrimoxazol, cefixime and ciprofloxacin antibiotics were 67%, 34% and 34% respectively. In 22 E. coli cases positive for integron class1 gene, resistance against three antibiotics were 100%, 95.45% and 90.90% respectively, which is statistically significant (p < 0.05).Conclusion:Resistance level against antibiotics in samples containing class 1 integron were significantly higher than those lacking this gene, which may be confirm the present of class 1 integron in creation of clinical strains with resistance to this antibiotics. Using suitable antibiotics may be preventing transmission of resistance genes through integrons.

Correlation of Multi-drug Resistance, Integron and blaESBL Gene Carriage With Genetic Fingerprints of Extended-Spectrum β-Lactamase Producing Klebsiella pneumoniae

Background:Some genetic and phenotypic variables are associated among distinct microbial populations.Objectives:The associations between multi-drug resistance (MDR) phenotypes, prevalence of antibiotic resistance integrons (ARIs), blaSHV, blaTEM and blaCTX-M gene carriage and genetic fingerprints of random amplified polymorphic DNA (RAPD), confirmed by pulsed field gel electrophoresis (PFGE), were investigated among extended-spectrum β-lactamases (ESBL)-producing nosocomial isolates of Klebsiella pneumoniae.Materials and Methods:Susceptibility of 35 ESBL-producing K. pneumoniae nosocomial isolates to 22 antimicrobial agents was determined. Integron carriage was detected using specific primers for intI1, intI2 and intI3 genes by PCR.Results:All isolates were resistant to piperacillin and susceptible to imipenem. MDR phenotype was observed in 91.4% of the isolates. Class 1 integrons were detected in 21 (60%) and class 2 integrons in 3 (8.57%) of the isolates. Two of the isolates carried both classes and none harbored class 3 integrons. Significant correlations were observed between resistance to aminoglycosides, fluoroquinolones and sulfonamides, and between genotype groups with carriage of ARIs, MDR phenotype and blaSHV gene carriage. ARI carriage was also significantly associated with MDR phenotype.Conclusions:Our findings suggest the possible co-carriage of some blaSHV genes and ARIs on the same plasmids harboring the MDR genes. Possible role of integrons in dissemination of ESBL-encoding blaSHV genes among ESBL-producing K. pneumoniae nosocomial isolates may be inferred.

English

Antibiotic resistance in bacteria still remains one of the leading concerns in global public health. Horizontal transfer of resistance genes is considered to be a major cause to facilitate the rapid spread of antibiotic resistance in microbes. In recent years, the role of integrons as mobile genetic elements playing a central role in horizontal transfer of antibiotic resistance have been well studied and documented. Nevertheless, up to date, most of the available investigations and studies on integron had focused on class 1 integrons of Gram-negative microorganisms. In the last decade, class 4 integrons (also known as super integrons) has been considered a major concern in antimicrobial resistance, as well as, a significant factor in bacterial genome evolution; however, most reports had been limited to Vibrio. Thus, this review is aimed at summarizing the occurrence and prevalence of integrons in bacterial isolates, with the focus on class 1 integron within Gram-positive bacteria, class 2 and 3 integrons. Key words: Antibiotic resistance, mobile genetic element, Class 1 integron, Class 2 integron, Class 3 integron, Gram-positive bacteria.

The function of integron-associated gene cassettes in Vibrio species: the tip of the iceberg

The integron is a genetic element that incorporates mobile genes termed gene cassettes into a reserved genetic site via site-specific recombination. It is best known for its role in antibiotic resistance with one type of integron, the class 1 integron, a major player in the dissemination of antibiotic resistance genes across Gram negative pathogens and commensals. However, integrons are ancient structures with over 100 classes (including class 1) present in bacteria from the broader environment. While, the class 1 integron is only one example of an integron being mobilized into the clinical environment, it is by far the most successful. Unlike clinical class 1 integrons which are largely found on plasmids, other integron classes are found on the chromosomes of bacteria and carry diverse gene cassettes indicating a non-antibiotic resistance role(s). However, there is very limited knowledge on what these alternative roles are. This is particularly relevant to Vibrio species where gene cassettes make up approximately 1–3% of their entire genome. In this review, we discuss how emphasis on class 1 integron research has resulted in a limited understanding by the wider research community on the role of integrons in the broader environment. This has the capacity to be counterproductive in solving or improving the antibiotic resistance problem into the future. Furthermore, there is still a significant lack of knowledge on how gene cassettes in Vibrio species drive adaptation and evolution. From research in Vibrio rotiferianus DAT722, new insight into how gene cassettes affect cellular physiology offers new alternative roles for the gene cassette resource. At least a subset of gene cassettes are involved in host surface polysaccharide modification suggesting that gene cassettes may be important in processes such as bacteriophage resistance, adhesion/biofilm formation, protection from grazers and bacterial aggregation.

Integron-associated resistance genes among multidrug-resistant Pseudomonas aeruginosa isolated from clinical specimens

To characterize common beta-lactamase genes and the role of integrons in beta-lactam antibiotic resistance among multidrug-resistant (MDR) P. aeruginosa strains isolated from intensive care units in Turkey. Materials and methods: After the examination of 67 P. aeruginosa isolates, 14 were found to be resistant to all of the tested beta-lactams and aminoglycosides. These 14 strains were studied to characterize the beta-lactamases and related integrons. Evaluation of minimum inhibitory concentrations, polymerase chain reaction (PCR) screening, isoelectric focusing, outer membrane isolation and analysis, and cloning and sequencing were performed according to published protocols. Results: PCR screening for common beta-lactamases detected PER-1 and OXA-10 among the selected MDR P. aeruginosa. PCR screening results showed that 2 of the isolates had 5'-3' class I integrons. Sequence analysis of the integrons revealed the existence of 6'-N-Nacetyltransferase (aac(6)-Ib) and streptomycin 3'-adenyl transferase (aadA2) cassettes (GenBank accession no. EF368053). Coexistence of PER-1 and OXA-2 and of PER-1 and OXA-10 was demonstrated in 8 and 7 of the isolates, respectively, by PCR. Shotgun cloning and PCR screening with relevant primers revealed the existence of a class I integron-associated blaOXA-2 gene cassette in 2 of the isolates. Strains positive for OXA-2 were also positive for PER-1. Conclusion: This study demonstrated the coexistence of PER-1 and OXA-2 in a single host. Coexistence of PER-1 with OXA-2 may increase the risk of the spreading of MDR P. aeruginosa in Turkish hospitals.

Epidemiology and molecular mechanism of integron-mediated antibiotic resistance in Shigella

Integrons are gene capture and expression systems that are characterized by the presence of an integrase gene. This encodes an integrase, a recombined site, and a promoter. They are able to capture gene cassettes from the environment and incorporate them using site-specific recombination. The role of integrons and gene cassettes in the dissemination of multidrug resistance in Gram-negative bacteria is significant. In Shigella species, antimicrobial resistance is often associated with the presence of class 1 and class 2 integrons that contain resistance gene cassettes. Multiple and complex expression regulation mechanisms involving mobile genetic elements in integrons have been developed in the evolution of Shigella strains. Knowledge of the epidemiology and molecular mechanisms of antimicrobial resistance in this important pathogen is essential for the implementation of intervention strategies. This review was conducted to introduce the structures and functions of integrons in Shigella species and mechanisms that control integron-mediated events linked to antibiotic resistance.

Identification and characterization of class 1 integrons among Pseudomonas aeruginosa isolates from patients in Zhenjiang, China

The role of integrons in the spread of antibiotic resistance has been well established. The aim of this study was to investigate the resistance profiles of Pseudomonas aeruginosa isolated from patients in Zhenjiang to 13 antibiotics, and to identify the structure and dissemination of class 1 integrons. The Kirby-Bauer disk diffusion assay was used to determine the rate of P. aeruginosa resistance. Class 1 integrons from multidrug-resistant isolates were amplified by PCR, and their PCR products were sequenced. We also analyzed the integron structures containing the same gene cassettes by restriction fragment length polymorphism (RFLP). Isolates were genotyped by pulsed-field gel electrophoresis (PFGE). The resistance rates were between 29.6% and 90.1%. The prevalence of class 1 integrons was 38.0%. These integrons included five gene cassettes (aadB, aac6-II, blaPSE-1, dfrA17, and aadA5). The dfrA17 and aadA5 gene cassettes were found most often. Class 1 integrons were found to be widespread in P. aeruginosa isolated from clinical samples in the Zhenjiang area of China. The antibiotic resistance rates in class 1 integron-positive strains of P. aeruginosa were noticeably higher than those in class 1 integron-negative strains. PFGE showed that particular clones were circulating among patients.

Occurrence of integrons and antimicrobial resistance genes among Salmonella enterica from Brazil

To determine the occurrence of antimicrobial resistance genes and role of integrons among 135 antimicrobial-resistant Salmonella enterica from Brazil. The presence of antimicrobial resistance genes, class 1 and 2 integrons and gene cassettes was analysed by PCR and sequencing. The genetic location of class 1 integrons was determined in 25 isolates by hybridization and plasmid transfer experiments. Fifty-five of the isolates were positive for class 1 integrons. Integron-positive isolates represented 17 different serovars and were mainly from human (n=28) and animal (n=13) sources. The gene cassette arrangements could be determined in 51 of the positive isolates, which harboured one [dfrA22, aadA1 or orf3 (putative trimethoprim resistance)], two [aadA1-dfrA1, aac(6')-Ib-orf1 (unknown function) or aacA4-aadA1], three [dfrA15b-cmlA4-aadA2, orf2 (unknown function)-dfrA5-orfD] or four [orf4-aacA4-blaOXA-30 (interrupted by an IS1 element)-aadA1] cassettes in their variable region. Only one isolate harboured a class 2 integron with the gene cassette array dfrA1-sat-aadA1. Several integron unrelated resistance genes were also detected in the isolates. Sulphonamide resistance was primarily mediated by sul2 and sul3, tetracycline resistance by tet(B) and tet(A), chloramphenicol resistance by catA1, streptomycin resistance by strA and ampicillin resistance by blaTEM. blaCTX and blaCMY-2 were found in cephalosporin-resistant isolates. Mating and hybridization experiments demonstrated that a high-molecular-weight plasmid mediated the gene transfer of integrons and additional resistance determinants. The present study revealed that integron-mediated resistance genes contributed to the multiresistance phenotype observed in the isolates, but most resistance genes were located outside the integron structure, as independent genes. However, they might be located on the same conjugative plasmid.

Integrons and multidrug resistance among Escherichia coli causing community-acquired urinary tract infection in southern India.

Antimicrobial resistance genes are often clustered in integrons, genetic elements capable of recombination. There is a paucity of data on the prevalence and role of integrons from community-acquired infections in developing countries where resistance to co-trimoxazole is high. We determined the prevalence of integrons among Escherichia coli causing community-acquired urinary tract infection (UTI). Consecutive isolates of E. coli obtained from UTI of pregnant women at the Christian Medical College Hospital, Vellore, India, during 2002 were included. All isolates were tested for susceptibility to 16 antimicrobials using the disc diffusion method and for integrons of classes 1 and 2 by PCR. Of the 58 isolates tested, 28 (48.3%) were resistant to co-trimoxazole and trimethoprim. All these isolates carried integrons. Three additional isolates were sulfonamide resistant but integron negative. Class 1 integrons were present in 21 (36.2%) isolates. Resistance to ampicillin (p=0.000), nalidixic acid (p=0.001), chloramphenicol (p=0.02), tetracycline (p=0.004) and gentamicin (p=0.02) was significantly more common in isolates with integrons. DNA sequencing of two isolates with integrons showed the presence of aadA, dfr1 and dfr7 genes. This study demonstrated that integrons are widely prevalent in India and that they might play a role in multidrug resistance in E. coli from community-acquired UTI.

The role of integrons in the dissemination of antibiotic resistance among clinical isolates of Pseudomonas aeruginosa from an intensive care unit in Brazil

Eighty-five Pseudomonas aeruginosa isolates resistant to various antibiotics were selected from the intensive care unit of a Brazilian hospital and analyzed for integron content by PCR. Fifty-four of them had class-1-related integrons, some of which were identical. Integron-positive isolates were statistically more resistant to aminoglicoside, quinolone and β-lactam compounds. Ribotyping of integron-positive isolates demonstrated the presence of identical integrons among genetically unrelated strains in the hospital environment, confirming its role in the spread of gene cassettes in bacterial populations of clinical importance.