scholarly journals Expression of the aac(6′)-Ib-cr Gene in Class 1 Integrons

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Sophie Raherison ◽  
Thomas Jove ◽  
Margaux Gaschet ◽  
Emilie Pinault ◽  
Aurore Tabesse ◽  
...  
Keyword(s):  
Amino Acids ◽  
Resistance Gene ◽  
Gene Cassette ◽  
Quinolone Resistance ◽  
Start Codon ◽  
Class 1 Integrons ◽  
Alternative Start Codon ◽  
Class 1

ABSTRACT aac(6′)-Ib-cr is a plasmid-mediated quinolone resistance gene embedded within a gene cassette, most often within an integron. It confers resistance to quinolones and aminoglycosides. We investigated the role of a 101-bp fragment frequently present upstream of the aac(6′)-Ib-cr gene cassette and found that it contributes to the expression of aac(6′)-Ib-cr and provides an alternative start codon, confirming the length of the AAC(6′)-Ib-cr protein to 199 amino acids.

scholarly journals Characterization of Class 1 Integrons from Pseudomonas aeruginosa That Contain the blaVIM-2Carbapenem-Hydrolyzing β-Lactamase Gene and of Two Novel Aminoglycoside Resistance Gene Cassettes

2001 ◽  
Vol 45 (2) ◽  
pp. 546-552 ◽  
Author(s):  
Laurent Poirel ◽  
Thierry Lambert ◽  
Salih Türkoglü ◽  
Esthel Ronco ◽  
Jean-Louis Gaillard ◽  
...  
Keyword(s):  
Amino Acids ◽  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Resistance Gene ◽  
Gene Cassette ◽  
Amino Acid Sequences ◽  
Aminoglycoside Resistance ◽  
Class 1 Integron ◽  
Gene Cassettes ◽  
Class 1

ABSTRACT Two clonally unrelated Pseudomonas aeruginosa clinical strains, RON-1 and RON-2, were isolated in 1997 and 1998 from patients hospitalized in a suburb of Paris, France. Both isolates expressed the class B carbapenem-hydrolyzing β-lactamase VIM-2 previously identified in Marseilles in the French Riviera. In both isolates, thebla VIM-2 cassette was part of a class 1 integron that also encoded aminoglycoside-modifying enzymes. In one case, two novel aminoglycoside resistance gene cassettes,aacA29a and aacA29b, were located at the 5′ and 3′ end of the bla VIM-2 gene cassette, respectively. The aacA29a and aacA29b gene cassettes were fused upstream with a 101-bp part of the 5′ end of theqacE cassette. The deduced amino acid sequence AAC(6′)-29a protein shared 96% identity with AAC(6′)-29b but only 34% identity with the aacA7-encoded AAC(6′)-I1, the closest relative of the AAC(6′)-I family enzymes. These aminoglycoside acetyltransferases had amino acid sequences much shorter (131 amino acids) than the other AAC(6′)-I enzymes (144 to 153 amino acids). They conferred resistance to amikacin, isepamicin, kanamycin, and tobramycin but not to gentamicin, netilmicin, and sisomicin.

scholarly journals Distribution and Content of Class 1 Integrons in Different Vibrio cholerae O-Serotype Strains Isolated in Thailand

2000 ◽  
Vol 44 (5) ◽  
pp. 1315-1321 ◽  
Author(s):  
Anders Dalsgaard ◽  
Anita Forslund ◽  
Oralak Serichantalergs ◽  
Dorthe Sandvang
Keyword(s):  
Antibiotic Resistance ◽  
Vibrio Cholerae ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Gene Cassette ◽  
Gene Cassettes ◽  
Class 1 Integrons ◽  
Class 1

ABSTRACT In this study, 176 clinical and environmental Vibrio cholerae strains of different O serotypes isolated in Thailand from 1982 to 1995 were selected and studied for the presence of class 1 integrons, a new group of genetic elements which carry antibiotic resistance genes. Using PCR and DNA sequencing, we found that 44 isolates contained class 1 integrons harboring the aadB,aadA2, blaP1, dfrA1, anddfrA15 gene cassettes, which encode resistance to gentamicin, kanamycin, and tobramycin; streptomycin and spectinomycin; β-lactams; and trimethoprim, respectively. Each cassette array contained only a single antibiotic resistance gene. Although resistance genes in class 1 integrons were found in strains from the same epidemic, as well as in unrelated non-O1, non-O139 strains isolated from children with diarrhea, they were found to encode only some of the antibiotic resistance expressed by the strains. Serotype O139 strains did not contain class 1 integrons. However, the appearance and disappearance of the O139 serotype in the coastal city Samutsakorn in 1992 and 1993 were associated with the emergence of a distinct V. cholerae O1 strain which contained the aadA2resistance gene cassette. A 150-kb self-transmissible plasmid found in three O1 strains isolated in 1982 contained the aadB gene cassette. Surprisingly, several strains harbored two integrons containing different cassettes. Thus, class 1 integrons containing various resistance gene cassettes are distributed among differentV. cholerae O serotypes of mainly clinical origin in Thailand.

scholarly journals Genetic Environment of Quinolone Resistance Gene qnrB2 in a Complex sul1-Type Integron in the Newly Described Salmonella enterica Serovar Keurmassar

2006 ◽  
Vol 50 (9) ◽  
pp. 3200-3202 ◽  
Author(s):  
Fabien Garnier ◽  
Nabil Raked ◽  
Amy Gassama ◽  
François Denis ◽  
Marie-Cécile Ploy
Keyword(s):  
Genetic Structure ◽  
Resistance Gene ◽  
Salmonella Enterica ◽  
Quinolone Resistance ◽  
Genetic Environment ◽  
Class 1 Integrons ◽  
Class 1

ABSTRACT A qnrB2 determinant was described for a new complex sul1-type integron from Salmonella enterica serovar Keurmassar. The genetic structure contained two class 1 integrons surrounding two common regions (CRs) separated by a partial 3′ conserved segment. The qnrB2 gene is adjacent to the first CR.

Prevalence and Molecular Characterization of Ampicillin-Resistant Enterobacteriaceae Isolated from Traditional Egyptian Domiati Cheese

2009 ◽  
Vol 72 (3) ◽  
pp. 624-630 ◽  
Author(s):  
AHMED M. HAMMAD ◽  
YOJIRO ISHIDA ◽  
TADASHI SHIMAMOTO
Keyword(s):  
Gene Cassette ◽  
Enteric Bacteria ◽  
Coli Strain ◽  
Quinolone Resistance ◽  
Animal Origin ◽  
Molecular Characteristics ◽  
Aminoglycoside Resistance ◽  
Class 1 Integrons ◽  
Class 1 ◽  
First Time

The aim of this study was to address the prevalence and the molecular characteristics of antibiotic-resistant enteric bacteria isolated from one of the most popular types of Egyptian cheese. A total of 215 ampicillin-resistant enterobacterial isolates were obtained from 80 samples of Domiati cheese, and they were screened by PCR for a large pool of antibiotic resistance markers, including extended-spectrum β-lactamases (ESBLs), class 1 and class 2 integrons, and plasmid-mediated quinolone resistance genes. It was determined that the most frequent mechanism of ampicillin resistance was from a TEM-1–type β-lactamase. As well, SHV β-lactamases, including SHV-1, SHV-25, and SHV-26, showed a high prevalence, and two novel SHV β-lactamases, SHV-110 and SHV-111, were identified. Type CTX-M-14, OXY-1, OXA-1, and CMY-4 β-lactamases were also detected in a few isolates. In addition, a novel AmpC β-lactamase was detected that was designated CMY-41. Sequencing results of class 1 integrons revealed that the uncommon aminoglycoside resistance gene cassette aadA22 was found for the first time in an Escherichia coli strain. The other class 1 integrons harbored various common gene cassettes, including aadA1, aadA1a, aadA2, aadA12, dfr5, dfr7, dfr12, and dfr15. The only isolate that carried a class 2 integron contained dfrA1, sat2, and aadA1. Plasmid-mediated quinolone resistance determinants qnrS and qnrB showed a low prevalence. This study provides meaningful data on high antimicrobial resistance contained in Domiati cheese samples and reports for the first time the presence of β-lactamases, plasmid-mediated quinolone resistance, and integrons in isolates from food of Egyptian animal origin.

scholarly journals New Integron-Associated Gene Cassette Encoding a Trimethoprim-Resistant DfrB-Type Dihydrofolate Reductase

2006 ◽  
Vol 50 (8) ◽  
pp. 2863-2865 ◽  
Author(s):  
Renee S. Levings ◽  
Diane Lightfoot ◽  
Liam D. H. Elbourne ◽  
Steven P. Djordjevic ◽  
Ruth M. Hall
Keyword(s):  
Dihydrofolate Reductase ◽  
Salmonella Enterica ◽  
Gene Cassette ◽  
Antibiotic Resistant ◽  
Class 1 Integrons ◽  
Class 1 ◽  
Type Gene

ABSTRACT A sixth gene cassette containing a dfrB-type gene, dfrB6, was found in a dfrB6-aadA1 cassette array in class 1 integrons. This array was isolated from several multiply antibiotic-resistant Salmonella enterica serovar Infantis strains that appear to be clonally related. The DfrB6 dihydrofolate reductase conferred resistance to trimethoprim.

Diversity of Gene Cassette Promoter Variants of Class 1 Integrons in Uropathogenic Escherichia coli

2013 ◽  
Vol 67 (5) ◽  
pp. 543-549 ◽  
Author(s):  
Quhao Wei ◽  
Xiaofei Jiang ◽  
Min Li ◽  
Gang Li ◽  
Qingfeng Hu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cassette ◽  
Uropathogenic Escherichia Coli ◽  
Class 1 Integrons ◽  
Class 1

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

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

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

scholarly journals Observations on the Role of TcdE Isoforms in Clostridium difficile Toxin Secretion

2015 ◽  
Vol 197 (15) ◽  
pp. 2600-2609 ◽  
Author(s):  
Revathi Govind ◽  
Leah Fitzwater ◽  
Rebekah Nichols
Keyword(s):  
Amino Acids ◽  
Clostridium Difficile ◽  
Cell Viability ◽  
Virulence Factors ◽  
Start Codon ◽  
Nosocomial Pathogen ◽  
Content Type ◽  
Antibiotic Associated Diarrhea ◽  
Toxin Secretion

ABSTRACTClostridium difficileis a major nosocomial pathogen and the principal causative agent of antibiotic-associated diarrhea. The toxigenicC. difficilestrains that cause disease secrete virulence factors, toxin A and toxin B, that cause colonic injury and inflammation.C. difficiletoxins have no export signature and are secreted by an unusual mechanism that involves TcdE, a holin-like protein. We isolated a TcdE mutant of the epidemic R20291 strain with impaired toxin secretion, which was restored by complementation with functional TcdE. In the TcdE open reading frame (ORF), we identified three possible translation start sites; each translated isoform may play a specific role in TcdE-controlled toxin release. We created plasmid constructs that express only one of the three TcdE isoforms and complemented the TcdE mutant with these isoforms. Western blot analysis of the complemented strains demonstrated that TcdE is translated efficiently from the start codon at the 25th and 27th positions in the predicted ORF, producing proteins with 142 amino acids (TcdE142) and 140 amino acids (TcdE140), respectively. TcdE166was not detected when expressed from its own ribosomal binding site (RBS). The effects of all three TcdE isoforms onC. difficilecell viability and toxin release were determined. Among the three isoforms, overexpression of TcdE166and TcdE142had a profound effect on cell viability compared to the TcdE140isoform. Similarly, TcdE166and TcdE142facilitated toxin release more efficiently than did TcdE140. The importance of these variations among TcdE isoforms and their role in toxin release are discussed.IMPORTANCEC. difficileis a nosocomial pathogen that has become the most prevalent cause of antibiotic-associated diarrhea in North America and in several countries in Europe. Most strains ofC. difficileproduce two high-molecular-weight toxins that are regarded as the primary virulence factors. The mechanism by which these large toxins are secreted from bacterial cells is not yet clear but involves TcdE, a holin-like protein. In this work, we show that TcdE could be translated from three different start codons, resulting in the production of three TcdE isoforms. Furthermore, we investigated the role of these isoforms in toxin release and cell lysis inC. difficile. An understanding of TcdE-dependent toxin secretion may be helpful for the development of strategies for preventing and treatingC. difficileinfections.

Sign in / Sign up

Export Citation Format

Share Document