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At least 199 records · Page 11Linked to original sources
PubMed2004

Variable resistance patterns of integron-associated multidrug-resistant Acinetobacter baumannii isolates in a surgical intensive care unit.

Between 1998 and 2000, we characterized 91 nosocomial isolates of Acinetobacter baumannii by antibiotyping and genotyping. A total of 25 ribotypes were obtained among these 91 isolates. When the isolates from surgical intensive care units (ICUs) and other wards were compared, multiresistant A. baumannii isolates with the same ribotype 25 (R-25) were significantly more prevalent in nosocomial infections among the surgical patients. Further subtyping of the strains by pulsed-field gel electrophoresis confirmed that strains of the same ribotype in surgical ICUs and a few isolates from other wards were identical or clonally related. Different antibiotic resistance profiles were observed among these R-25 isolates. All R-25 isolates contained intI1 integrase, and two clusters of integron cassettes were found. These clusters of cassettes were encoded by an open reading frame (ORF) of -5'CS-aac(3)Ia-aadA1a-unknown or f-3'CS or 5'CS-aacA4-aadA1-catB8-3'CS, indicating the involvement of different resistant genes. Two isolates contained bla (IMP-1), which was acquired from a conjugatively transferable plasmid and did not involve integron-associated resistance. In conclusion, an epidemic of nosocomial infections associated with A. baumannii strains that have different resistance profiles was identified. Resistance profiles can change by a combination of plasmid- and integron-associated acquisition, especially in a unit with high antibiotic selective pressures. Infectious control personnel should be alert to the change in resistance profiles during routine monitoring.

Acinetobacter Infections↗
PubMed2005

Integrons in Escherichia coli from food-producing animals in The Netherlands.

The presence and character of class 1 integrons in multidrug-resistant Escherichia coli from slaughter animals and meat was determined by integrase-specific PCR and conserved segment PCR-restriction fragment length polymorphism (RFLP). At least five different class 1 integron types were found and three types were shared between hospitalized patients, humans in the community, meat, and slaughter animals. Common integron types indicate that antibiotic resistance genes are exchanged via the food chain between different reservoirs of both human and animal origin.

Animals↗
PubMed2003

An integron cassette encoding erythromycin esterase, ere(A), from Providencia stuartii.

We have mapped the variable region of the two class 1 integrons found in the multiresistant strain Providencia stuartii 1723. Integron 1 contains a new arrangement of gene cassettes, aacA4-aadB-aadA1, conferring resistance to all aminoglycosides used for clinical treatment. Integron 2 contains a variant of the gene cassette ere(A), coding for an erythromycin esterase, whose nucleotide sequence shares 93.7% DNA identity with ere(A) from Escherichia coli BM2195 plasmid pIP1100.

Carboxylic Ester Hydrolases↗
PubMed2004

New aminoglycoside acetyltransferase gene, aac(3)-Id, in a class 1 integron from a multiresistant strain of Vibrio fluvialis isolated from an infant aged 6 months.

OBJECTIVES: To characterize the molecular basis of antibiotic resistance in a multidrug-resistant clinical isolate of Vibrio fluvialis H-08942. PATIENT AND METHODS: V. fluvialis H-08942 was isolated from a hospitalized infant aged 6 months suffering from cholera-like diarrhoea in India in 2002. The broth microdilution method was used to determine the MICs of a range of antibiotics for this strain. PCR, DNA sequencing, Southern hybridization, cloning and expression were used to characterize the molecular basis of antibiotic resistances. RESULTS: V. fluvialis H-08942 showed resistance to chloramphenicol, streptomycin, spectinomycin, co-trimoxazole, ampicillin, furazolidone, nalidixic acid and gentamicin. A class 1 integron that contains a novel aminoglycoside acetyltransferase gene, aac(3)-Id, and aminoglycoside adenyltransferase gene, aadA7, was characterized. The aac(3)-Id gene product was found to share 50%, 45% and 44% identity to AAC(3)-Ic, AAC(3)-Ia, and AAC(3)-Ib, respectively. Both aac(3)-Id and aadA7 genes were cloned and expressed in Escherichia coli. Phylogenetic analysis suggested that the aac(3)-Id represents a fourth evolutionary lineage in the aminoglycoside acetyltransferase genes. Southern hybridization showed that this integron is located in the chromosome. CONCLUSIONS: In this study we identified a new type of aminoglycoside acetyltransferase gene, aac(3)-Id. In addition, this is the first report of identification of antibiotic resistance genes and a class 1 integron in V. fluvialis.

Acetyltransferases↗
PubMed2004

Trends in antimicrobial resistance, phage types and integrons among Salmonella serotypes from pigs, 1997-2000.

OBJECTIVES: The objectives of this study were to determine antimicrobial resistance and to identify phage types and class 1 integrons among non-typhoidal Salmonella isolates from 24 pig farms in North Carolina collected between 1997 and 2000. METHODS: A total of 1314 isolates of 30 serotypes from pig faecal samples were collected and analysed over a 3 year period. The isolates were characterized using antimicrobial susceptibility testing, phage typing, PCR and DNA sequencing for class 1 integrons. RESULTS: A high frequency of resistance to antimicrobial agents including tetracycline (85%), ampicillin (47%), co-amoxiclav (23%) and chloramphenicol (21%) was detected. Two multidrug resistance patterns were common in Typhimurium (including variant Copenhagen): isolates with co-amoxiclav, ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and tetracycline (R-type AxACSSuT) [36%] and isolates with ampicillin, kanamycin, streptomycin, sulfamethoxazole and tetracycline (R-type AKSSuT) [45%] resistance patterns. Definitive Type 104 (DT104) was the most common (34%) among eight phage types identified. AKSSuT was found among non-DT104 phage types, particularly DT21 and DT193. Class 1 integrons were detected among various serotypes including Typhimurium, Derby, Muenchen, Worthington, Bere and Muenster. aadA was the most common resistance gene insert, and the oxa30 beta-lactamase resistance gene was also identified among serovar Muenchen. CONCLUSIONS: In this study, two most important multidrug resistance patterns (AxACSSuT and AKSSuT) and phage types of public health significance (DT104 and DT193) constituted two-thirds of the serotype Typhimurium isolates. The findings imply that pigs raised in the commercial production system may pose a risk in serving as reservoirs of resistant Salmonella.

Animals↗
PubMed2004

Dissemination amongst humans and food products of animal origin of a Salmonella typhimurium clone expressing an integron-borne OXA-30 beta-lactamase.

OBJECTIVES: Characterization of the molecular basis for beta-lactam resistance and evaluation of the clonal relatedness among nine isolates of multidrug-resistant Salmonella typhimurium recovered from seven clinical human samples and two pork end products. METHODS: The isolates were examined for susceptibility to antimicrobial agents. The relationships between resistance genes, class 1 integrons, plasmids and isolates were screened by molecular methods such as polymerase chain reaction and restriction fragment length analysis. RESULTS: A bla(OXA-30) gene, located in a class 1 integron, was detected in all isolates. This integron was present on a conjugative plasmid in all but one isolate. By pulsed-field gel electrophoresis, it was determined that all strains share the same chromosomal type. CONCLUSIONS: This study demonstrates the spread of an OXA-30-producing S. typhimurium in Portugal, suggesting dissemination of a resistant clone through the food chain.

Animals↗
PubMed2004

Integron-mediated ESBL resistance in rare serotypes of Escherichia coli causing infections in an elderly population of Israel.

OBJECTIVES: To identify and characterize the aetiology of an outbreak of extra-intestinal multidrug-resistant Escherichia coli infections in elderly patients in Israel. METHODS: Extended-spectrum beta-lactamase (ESBL)-producing clinical isolates of E. coli from extra-intestinal sources were tested for susceptibility to non-beta-lactam drugs, and their serotypes were determined. Restriction enzyme digestion, followed by PFGE of DNA purified from isolates, was used to classify the phylogenetic relationship between them. Plasmid DNA from five isolates of different serotypes was used to transform an E. coli laboratory strain. The plasmids were partially sequenced. RESULTS: E. coli isolates from 86 patients, mostly elderly, were shown to be positive for inhibitor-susceptible ESBLs, and more resistant to cefotaxime than to ceftazidime. Ninety-six per cent of ESBL producers were also resistant to gentamicin, and 100% to trimethoprim/sulfamethoxazole and ciprofloxacin. All isolates belonged to one of five serotypes. PFGE analysis of purified DNA yielded 17 profiles. Sequencing of plasmids isolated from the transformants identified sul1, aac(6')-Ib and bla(CTX-M-2). These genes were embedded in an integron, InS21. CONCLUSIONS: Extra-intestinal infections with ESBL-producing E. coli of different serotypes and probably mixed clonality showed a surprising homogeneity in resistance profiles, with 100% being co-resistant to ciprofloxacin and trimethoprim/sulfamethoxazole, and 96% to gentamicin. Plasmid DNA from three isolates from different serotypes contained integron InS21, previously demonstrated in Salmonella enterica from Argentina. This is the first molecular identification of an ESBL gene and integron in Israel or neighbouring geographical areas.

Aged↗
PubMed2006

Common regions e.g. orf513 and antibiotic resistance: IS91-like elements evolving complex class 1 integrons.

The ability of bacteria to procure, sometimes rearrange, and evince acquired DNA continues to impress us-even more so if this genetic plasticity involves the sequestering of antibiotic resistance genes. The acquisition of genes in bacteria is often facilitated by transposons, integrons and archetype insertion elements. Recently however, a new element, 'orf513', has been increasingly associated with class 1 integrons. Moreover, these 'complex' class 1 integrons can potentially mediate resistance to chloramphenicol, trimethoprim, aminoglycosides and tetracycline and may carry a range of beta-lactamase genes as well as the qnrA gene. Elements such as 'orf513' demonstrate IS91-like characteristics and will mobilize adjacent DNA via a process called rolling circle replication, and thus we have renamed them 'insertion sequence CRs' (ISCRs) to appropriately reflect their structure-function properties. In this article, we provide a brief description of these new and clinically important mobile elements, and how they are able to mobilize antibiotic resistance genes.

Anti-Bacterial Agents↗
PubMed2003

Characterization of class I integrons in clinical strains of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis from Norwegian hospitals.

The characterization of integrons and their promoters in 156 antibiotic-resistant clinical isolates of the important zoonotic pathogens Salmonella enterica subsp. enterica serovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) from Norwegian hospitals were performed. Integrons were found in 64 of 66 S. Typhimurium isolates (97 %) and in 20 of 90 S. Enteritidis isolates (22.2 %) with the following sizes; 650, 1000, 1200, 1500, 1600, 1700, 2000 and 2100 bp. The integrons were further sequenced and the aadA1, aadA2, aadA5, aadB, pse-1, catB3, oxa1, dfrA1, dfrA12 and dfrA17 genes, as well as a fragment of the sat1 gene, were found embedded in cassettes. An internal fragment of the purG gene was additionally found as an artefact PCR amplicon.

Anti-Bacterial Agents↗
PubMed2004

Identification and characterization of class 1 integron resistance gene cassettes among Salmonella strains isolated from healthy humans in China.

Twenty-three strains of Salmonella spp. isolated from healthy humans in Guangdong, China, were examined for their susceptibility to ten common antibiotics and the presence of antibiotic resistance integrons. All the strains were resistant to at least one antibiotic, and 4 strains were positive for the intI1 gene. Polymerase chain reaction using in-F and in-B primers showed the existence of amplicons of 1,009 bp in two, 1,664 bp in one, and 1,009 bp and 1,664 bp in one of the intI1 -positive isolates, respectively. Sequence analysis revealed that the 1,009-bp amplicon harbored gene cassette aadA2, conferring resistance to spectinomycin, and the 1,664-bp amplicon harbored genes aadA5 and dfr17, conferring resistance to spectinomycin, streptomycin and trimethoprim. Meanwhile the experiments of plasmid conjugation and Southern hybridization with intI1 as the DNA probe indicated that all the integrons found in these strains were chromosomal. Because the strains carrying class 1 integrons were isolated from healthy humans, it suggests the need for all-round surveillance of the antibiotic resistance of pathogens.

Anti-Bacterial Agents↗
PubMed2006

Unnoticed spread of class 1 integrons in gram-positive clinical strains isolated in Guangzhou, China.

A total of 46 gram-positive bacteria isolated from clinical specimens collected in China were subjected to PCR analysis with the intI1-specific primers, and the intI1-positive strains were further analyzed for their resistance gene cassette. All isolates possessed the class 1 integron in their genomes and the array of gene cassettes was dhfrXII-orfF-aadA2, which is very similar to other organisms except in one isolate carrying an additional copy of the class 1 integron containing the aadA2 gene cassette. Altogether, the results indicate that the class 1 integron is widespread in gram-positive clinical strains isolated in Guangzhou, China.

Drug Resistance, Bacterial↗
PubMed2007

Investigation of a global collection of nontyphoidal Salmonella of various serotypes cultured between 1953 and 2004 for the presence of class 1 integrons.

In this study, antibiotic resistance profiles, and the presence of class 1 integrons were determined for 108 Salmonella isolates comprising 37 serotypes cultured from a variety of sources between 1953 and 2004. Antibiogram analyses showed that all isolates were resistant to streptomycin/spectinomycin. Molecular analysis revealed that 50% of the collection contained an integrase-encoding gene (int1) and 25% contained class 1 integrons. A Salmonella Wien isolate possessing a complete class 1 integron with a dfrA5-ereA2 gene arrangement within the variable region was characterized.

Anti-Bacterial Agents↗
PubMed2002

Molecular characterization of integrons in epidemiologically unrelated clinical isolates of Acinetobacter baumannii from Italian hospitals reveals a limited diversity of gene cassette arrays.

Integron carriage by 36 epidemiologically unrelated Acinetobacter baumannii isolates collected over an 11-year period from patients in six different Italian hospitals was investigated. Sixteen type 1 integron-positive isolates (44%) were found, 13 of which carried the same array of cassettes, i.e., aacC1, orfX, orfX', and aadA1a. As ribotype analysis of the isolates demonstrated a notable genetic diversity, horizontal transfer of the entire integron structure or ancient acquisition was hypothesized.

Acinetobacter Infections↗
PubMed2003

Multiple-drug resistance in D-tartrate-positive Salmonella enterica serovar paratyphi B isolates from poultry is mediated by class 2 integrons inserted into the bacterial chromosome.

The presence of integrons in 85 multiresistant German isolates of the predominating Salmonella enterica subsp. enterica serovar Paratyphi B dT(+) clone was investigated. All isolates possessed a chromosomally located Tn7-like class 2 integron carrying the same dfrA1-sat1-aadA1 array of gene cassettes. Only four isolates (4.7%) revealed an additional class 1 integron with two strains each containing the aadA1 or dfrA1-aadA1 gene cassettes.

Animals↗
PubMed2003

Integron-containing IncU R plasmids pRAS1 and pAr-32 from the fish pathogen Aeromonas salmonicida.

A 45-kb R plasmid, pRAS1, that confers resistance to tetracyclines, trimethoprim, and sulfonamides was isolated in 1989 from an atypical strain of the fish pathogen Aeromonas salmonicida. This plasmid could be transferred by conjugation to Escherichia coli with a high degree of efficiency (frequency, 0.48). The following year pRAS1 was isolated from A. salmonicida subsp. salmonicida in the same area. Incompatibility group U plasmid pRAS1 contained a drug resistance-determining region of 12 kb consisting of a class 1 integron similar to In4 of Tn1696 but with a dfrA16 gene cassette inserted. Close to IS6100 at the right end of Tn4 was a truncated Tn1721. Restriction enzyme analysis showed that R plasmid pAr-32, isolated from A. salmonicida in Japan in 1970, had the same backbone structure as pRAS1, while the drug resistance-determining region contained a complex class 1 integron with an aadA2 cassette; the chloramphenicol resistance gene catA2, as in In6 of pSa; and a duplicate of the 3' conserved segment of the integron.

Aeromonas↗
PubMed2006

In117, an unusual In0-like class 1 integron containing CR1 and bla(CTX-M-2) and associated with a Tn21-like element.

An unusual In0-like class 1 integron containing a common region that includes the putative recombinase gene named orf513 (CR1) and bla(CTX-M-2) was characterized from Escherichia coli. The integron contained an unusual gene cassette array, estX-aadA1, embedded between the 5'-conserved segment (5'-CS) and 3'-CS1 regions and was flanked by mer-Tn21 sequences downstream of the tni truncated module. This element constitutes one of the few examples of CR1-bearing class 1 integrons that has been fully characterized.

Base Sequence↗
PubMed2003

Changes in patterns of antimicrobial susceptibility and integron carriage among Shigella sonnei isolates from southwestern Korea during epidemic periods.

Shigella sonnei isolates from southwestern Korea during the epidemic periods of 1998 to 2000 were genetically related. The antimicrobial susceptibilities of the outbreak-related isolates changed annually. All isolates carried class 2 integrons, and the outbreak-related isolates from 1999 also carried class 1 integrons. The antimicrobial susceptibilities of S. sonnei isolates are readily changed by antibiotic selective pressures, and integrons are responsible for resistance to antimicrobial agents commonly used to treat shigellosis.

Disease Outbreaks↗
PubMed2006

Origin of class 1 and 2 integrons and gene cassettes in a population-based sample of uropathogenic Escherichia coli.

The prevalence of urinary tract infections (UTI) caused by trimethoprim-sulfamethoxazole (TMP-SMX)-resistant Escherichia coli is increasing and varies geographically in the United States. Recent community-based UTI studies have demonstrated geographic clustering of an Escherichia coli clonal group, suggesting occurrence of a community outbreak of UTI. A large proportion of this clonal group (designated CgA) isolated from women in a California college community was found to be resistant to TMP-SMX. We wished to determine if the acquisition of TMP-SMX resistance by CgA occurred before or after the CgA strains were introduced into this community. Between October 1999 and January 2000 and between October 2000 and January 2001, 482 E. coli isolates were consecutively collected from the urine samples of women with UTI at a student health clinic and analyzed for determinants of TMP-SMX resistance. In particular, the distribution of integrons harboring resistance cassettes for TMP-SMX (dfr) was examined. Among 95 TMP-SMX-resistant isolates, 68 and 27 isolates carried class 1 and class 2 integrons, respectively. A class 1 integron was found in 25 (93%) of 27 TMP-SMX-resistant CgA isolates but in only 43 (63%) of 68 TMP-SMX-resistant non-CgA isolates (P < 0.001) and in none of 44 TMP-SMX-susceptible E. coli isolates (P < 0.0001). CgA strains carried only a single arrangement of class 1 gene cassettes (dfrA17-aadA5), while the non-clonal group strains carried nine different cassette arrangements. These results support the idea that CgA strains acquired their resistance at a common site prior to their spread to the college community.

Escherichia coli↗