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Gabriel Gutkind - One of the best experts on this subject based on the ideXlab platform.
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biochemical and molecular characterization of three new variants of ampc β lactamases from Morganella morganii
Antimicrobial Agents and Chemotherapy, 2006Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Gabriel GutkindAbstract:Morganella morganii produces an inducible, chromosomally encoded AmpC β-lactamase. We describe in this study three new variants of AmpC within this species with apparent pIs of 6.6 (M19 from M. morganii strain PP19), 7.4 (M29 from M. morganii strain PP29), and 7.8 (M37 from M. morganii strain PP37). After gene sequencing, deduced amino acid sequences displayed one to six substitutions when compared to the available Morganella AmpC sequences. An AmpR-encoding gene was also found upstream of ampC , including the LysR regulators9 helix-turn-helix DNA-binding domain and the putative T-N 11 -A-protected region in the ampR-ampC intercistronic sequence. All three AmpC variants were purified from in vitro-generated derepressed mutants and showed overall similar kinetic parameters. None of the observed amino acid changes, occurring at the surface of the protein, appear to have a major influence in their catalytic properties. Morganella AmpCs exhibit the highest catalytic efficiencies ( k cat / K m ) on classical penicillins, cefoxitin, narrow-spectrum cephalosporins, and cefotaxime. Cefotaxime was more effectively hydrolyzed than other oxyimino-cephalosporins, whereas cefepime was 3 log-fold less efficiently hydrolyzed than other cephalosporins such as cephalothin. Several differences with other AmpC β-lactamases were found. Ampicillin was more efficiently hydrolyzed than benzylpenicillin. High k cat /K m values were observed for oxacillin and piperacillin, which are usually poor substrates for AmpC. A fairly efficient hydrolysis of imipenem was detected as well. Aztreonam, carbenicillin, and tazobactam were effective transient inactivators of these variants.
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives: We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods: bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions: A class 1 integron (in116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 β-lactamase. The variable region of In116 contains aacA4, bla OXA-2 and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla CTX-M-2 and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla CTX-M-2- .
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions A class 1 integron (In116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 beta-lactamase. The variable region of In116 contains aacA4, bla(OXA-2) and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla(CTX-M-2) and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla(CTX-M-2).
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cefotaxime hydrolysing beta lactamases in Morganella morganii
European Journal of Clinical Microbiology & Infectious Diseases, 1999Co-Authors: Pablo Power, Marcela Radice, Claudia Barberis, C De Mier, Marta Mollerach, M Maltagliatti, Carlos Vay, Angela Famiglietti, Gabriel GutkindAbstract:The frequency of enterobacterial isolates with high resistance to expanded-spectrum β-lactam antibiotics (mainly cefotaxime or ceftriaxone) has increased notoriously in Argentina, mainly because of the spread of extended-spectrum β-lactamases. The aim of this work was the study of extended-spectrum β-lactamases in several Morganella morganii isolates with unusually high resistance to ceftriaxone. These strains produced at least two β-lactamases, of apparent pIs of 5.4 and 8.2, molecular weight 23 000, well inhibited by clavulanate, compatible with a broad-spectrum β-lactamase – perhaps TEM-1 – and an extended-spectrum β-lactamase, respectively. The extended-spectrum β-lactamase was identified as a CTX-M-type β-lactamase – probably CTX-M-2 – by polymerase chain reaction, restriction profile analysis and DNA-DNA hybridisation. The remaining isolates studied produced either the broad-spectrum β-lactamase plus the ubiquitous AmpC β-lactamase (13 strains), or the AmpC β-lactamase only (10 strains).
Pablo Power - One of the best experts on this subject based on the ideXlab platform.
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biochemical and molecular characterization of three new variants of ampc β lactamases from Morganella morganii
Antimicrobial Agents and Chemotherapy, 2006Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Gabriel GutkindAbstract:Morganella morganii produces an inducible, chromosomally encoded AmpC β-lactamase. We describe in this study three new variants of AmpC within this species with apparent pIs of 6.6 (M19 from M. morganii strain PP19), 7.4 (M29 from M. morganii strain PP29), and 7.8 (M37 from M. morganii strain PP37). After gene sequencing, deduced amino acid sequences displayed one to six substitutions when compared to the available Morganella AmpC sequences. An AmpR-encoding gene was also found upstream of ampC , including the LysR regulators9 helix-turn-helix DNA-binding domain and the putative T-N 11 -A-protected region in the ampR-ampC intercistronic sequence. All three AmpC variants were purified from in vitro-generated derepressed mutants and showed overall similar kinetic parameters. None of the observed amino acid changes, occurring at the surface of the protein, appear to have a major influence in their catalytic properties. Morganella AmpCs exhibit the highest catalytic efficiencies ( k cat / K m ) on classical penicillins, cefoxitin, narrow-spectrum cephalosporins, and cefotaxime. Cefotaxime was more effectively hydrolyzed than other oxyimino-cephalosporins, whereas cefepime was 3 log-fold less efficiently hydrolyzed than other cephalosporins such as cephalothin. Several differences with other AmpC β-lactamases were found. Ampicillin was more efficiently hydrolyzed than benzylpenicillin. High k cat /K m values were observed for oxacillin and piperacillin, which are usually poor substrates for AmpC. A fairly efficient hydrolysis of imipenem was detected as well. Aztreonam, carbenicillin, and tazobactam were effective transient inactivators of these variants.
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives: We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods: bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions: A class 1 integron (in116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 β-lactamase. The variable region of In116 contains aacA4, bla OXA-2 and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla CTX-M-2 and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla CTX-M-2- .
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions A class 1 integron (In116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 beta-lactamase. The variable region of In116 contains aacA4, bla(OXA-2) and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla(CTX-M-2) and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla(CTX-M-2).
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cefotaxime hydrolysing beta lactamases in Morganella morganii
European Journal of Clinical Microbiology & Infectious Diseases, 1999Co-Authors: Pablo Power, Marcela Radice, Claudia Barberis, C De Mier, Marta Mollerach, M Maltagliatti, Carlos Vay, Angela Famiglietti, Gabriel GutkindAbstract:The frequency of enterobacterial isolates with high resistance to expanded-spectrum β-lactam antibiotics (mainly cefotaxime or ceftriaxone) has increased notoriously in Argentina, mainly because of the spread of extended-spectrum β-lactamases. The aim of this work was the study of extended-spectrum β-lactamases in several Morganella morganii isolates with unusually high resistance to ceftriaxone. These strains produced at least two β-lactamases, of apparent pIs of 5.4 and 8.2, molecular weight 23 000, well inhibited by clavulanate, compatible with a broad-spectrum β-lactamase – perhaps TEM-1 – and an extended-spectrum β-lactamase, respectively. The extended-spectrum β-lactamase was identified as a CTX-M-type β-lactamase – probably CTX-M-2 – by polymerase chain reaction, restriction profile analysis and DNA-DNA hybridisation. The remaining isolates studied produced either the broad-spectrum β-lactamase plus the ubiquitous AmpC β-lactamase (13 strains), or the AmpC β-lactamase only (10 strains).
Alain Philippon - One of the best experts on this subject based on the ideXlab platform.
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a novel integron in salmonella enterica serovar enteritidis carrying the bla dha 1 gene and its regulator gene ampr originated from Morganella morganii
Antimicrobial Agents and Chemotherapy, 2000Co-Authors: Charlotte Verdet, Guilene Barnaud, Guillaume Arlet, P H Lagrange, Alain PhilipponAbstract:The genetic organization of the gene coding for DHA-1 and the corresponding ampR gene was determined by PCR mapping. These genes have been mobilized from the Morganella morganii chromosome and inserted into a complex sulI-type integron, similar to In6 and In7. However, they are not themselves mobile cassettes. This integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for blaCMY-1 and blaMOX-1.
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salmonella enteritidis ampc plasmid mediated inducible β lactamase dha 1 with an ampr gene from Morganella morganii
Antimicrobial Agents and Chemotherapy, 1998Co-Authors: Guilene Barnaud, Guillaume Arlet, Charlotte Verdet, Olivier Gaillot, P H Lagrange, Alain PhilipponAbstract:DHA-1, a plasmid-mediated cephalosporinase from a single clinical Salmonella enteritidis isolate, conferred resistance to oxyimino-cephalosporins (cefotaxime and ceftazidime) and cephamycins (cefoxitin and moxalactam), and this resistance was transferable to Escherichia coli HB101. An antagonism was observed between cefoxitin and aztreonam by the diffusion method. Transformation of the transconjugant E. coli strain with plasmid pNH5 carrying the ampD gene (whose product decreases the level of expression of ampC) resulted in an eightfold decrease in the MIC of cefoxitin. A clone with the same AmpC susceptibility pattern with antagonism was obtained, clone E. coli JM101(pSAL2-ind), and its nucleotide sequence was determined. It contained an open reading frame with 98.7% DNA sequence identity with the ampC gene of Morganella morganii. DNA sequence analysis also identified a gene upstream of ampC whose sequence was 97% identical to the partial sequence of the ampR gene (435 bp) from M. morganii. The gene encoded a protein with an amino-terminal DNA-binding domain typical of transcriptional activators of the LysR family. Moreover, the intercistronic region between the ampC and ampR genes was 98% identical to the corresponding region from M. morganii DNA. AmpR was shown to be functional by enzyme induction and a gel mobility-shift assay. An ampG gene was also detected in a Southern blot of DNA from the S. enteritidis isolate. These findings suggest that this inducible plasmid-mediated AmpC type β-lactamase, DHA-1, probably originated from M. morganii.
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cloning and sequencing of the gene encoding the ampc β lactamase of Morganella morganii
Fems Microbiology Letters, 1997Co-Authors: Guilene Barnaud, Guillaume Arlet, Claude Danglot, Alain PhilipponAbstract:The chromosomal β-lactamase gene of a clinical isolate of Morganella morganii was cloned in Escherichia coli and sequenced. The β-lactamase had a pI of 7.4 and conferred a typical AmpC susceptibility pattern. The insert obtained was found to encode a protein of 379 amino acids. Its deduced amino acid sequence revealed it to be a class C β-lactamase: 39–56% identity with chromosomal AmpC β-lactamases of Serratia marcescens, Yersinia enterocolitica, Citrobacter freundii, Enterobacter cloacae and Escherichia coli; and 37–56% identity with plasmid-mediated β-lactamases (MOX-1, CMY-1, FOX-1, ACT-1, LAT-1, BIL-1 and CMY-2). The ampC gene was linked to a gene only part of which (450 bp) was cloned homologous to the regulatory ampR genes of chromosomal class C β-lactamases.
Moreno Galleni - One of the best experts on this subject based on the ideXlab platform.
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biochemical and molecular characterization of three new variants of ampc β lactamases from Morganella morganii
Antimicrobial Agents and Chemotherapy, 2006Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Gabriel GutkindAbstract:Morganella morganii produces an inducible, chromosomally encoded AmpC β-lactamase. We describe in this study three new variants of AmpC within this species with apparent pIs of 6.6 (M19 from M. morganii strain PP19), 7.4 (M29 from M. morganii strain PP29), and 7.8 (M37 from M. morganii strain PP37). After gene sequencing, deduced amino acid sequences displayed one to six substitutions when compared to the available Morganella AmpC sequences. An AmpR-encoding gene was also found upstream of ampC , including the LysR regulators9 helix-turn-helix DNA-binding domain and the putative T-N 11 -A-protected region in the ampR-ampC intercistronic sequence. All three AmpC variants were purified from in vitro-generated derepressed mutants and showed overall similar kinetic parameters. None of the observed amino acid changes, occurring at the surface of the protein, appear to have a major influence in their catalytic properties. Morganella AmpCs exhibit the highest catalytic efficiencies ( k cat / K m ) on classical penicillins, cefoxitin, narrow-spectrum cephalosporins, and cefotaxime. Cefotaxime was more effectively hydrolyzed than other oxyimino-cephalosporins, whereas cefepime was 3 log-fold less efficiently hydrolyzed than other cephalosporins such as cephalothin. Several differences with other AmpC β-lactamases were found. Ampicillin was more efficiently hydrolyzed than benzylpenicillin. High k cat /K m values were observed for oxacillin and piperacillin, which are usually poor substrates for AmpC. A fairly efficient hydrolysis of imipenem was detected as well. Aztreonam, carbenicillin, and tazobactam were effective transient inactivators of these variants.
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives: We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods: bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions: A class 1 integron (in116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 β-lactamase. The variable region of In116 contains aacA4, bla OXA-2 and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla CTX-M-2 and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla CTX-M-2- .
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions A class 1 integron (In116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 beta-lactamase. The variable region of In116 contains aacA4, bla(OXA-2) and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla(CTX-M-2) and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla(CTX-M-2).
Juan A Ayala - One of the best experts on this subject based on the ideXlab platform.
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biochemical and molecular characterization of three new variants of ampc β lactamases from Morganella morganii
Antimicrobial Agents and Chemotherapy, 2006Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Gabriel GutkindAbstract:Morganella morganii produces an inducible, chromosomally encoded AmpC β-lactamase. We describe in this study three new variants of AmpC within this species with apparent pIs of 6.6 (M19 from M. morganii strain PP19), 7.4 (M29 from M. morganii strain PP29), and 7.8 (M37 from M. morganii strain PP37). After gene sequencing, deduced amino acid sequences displayed one to six substitutions when compared to the available Morganella AmpC sequences. An AmpR-encoding gene was also found upstream of ampC , including the LysR regulators9 helix-turn-helix DNA-binding domain and the putative T-N 11 -A-protected region in the ampR-ampC intercistronic sequence. All three AmpC variants were purified from in vitro-generated derepressed mutants and showed overall similar kinetic parameters. None of the observed amino acid changes, occurring at the surface of the protein, appear to have a major influence in their catalytic properties. Morganella AmpCs exhibit the highest catalytic efficiencies ( k cat / K m ) on classical penicillins, cefoxitin, narrow-spectrum cephalosporins, and cefotaxime. Cefotaxime was more effectively hydrolyzed than other oxyimino-cephalosporins, whereas cefepime was 3 log-fold less efficiently hydrolyzed than other cephalosporins such as cephalothin. Several differences with other AmpC β-lactamases were found. Ampicillin was more efficiently hydrolyzed than benzylpenicillin. High k cat /K m values were observed for oxacillin and piperacillin, which are usually poor substrates for AmpC. A fairly efficient hydrolysis of imipenem was detected as well. Aztreonam, carbenicillin, and tazobactam were effective transient inactivators of these variants.
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives: We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods: bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions: A class 1 integron (in116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 β-lactamase. The variable region of In116 contains aacA4, bla OXA-2 and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla CTX-M-2 and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla CTX-M-2- .
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description of in116 the first blactx m 2 containing complex class 1 integron found in Morganella morganii isolates from buenos aires argentina
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Pablo Power, Moreno Galleni, Juan A Ayala, Jose Di Conza, Gabriel GutkindAbstract:Objectives We analysed the architecture and probable origin of a class 1 integron from cefotaxime-resistant Morganella morganii isolates. Methods bla genes and class 1 integron elements were detected by PCR and DNA-DNA hybridization in a M. morganii strain isolated in 1996. PCR-mapping and sequencing of different fragments were carried out to determine the integron's architecture. Results and conclusions A class 1 integron (In116), strongly related to the In6/In7 family, was detected in a plasmid from an oxyimino-cephalosporin-resistant M. morganii strain, producing CTX-M-2 beta-lactamase. The variable region of In116 contains aacA4, bla(OXA-2) and orfD cassettes. Downstream of the 3'-conserved-segment (3'-CS), an orf513-containing common region is followed by bla(CTX-M-2) and flanking regions, having 96-99% nucleotide identity with Kluyvera ascorbata's kluA-1 and neighbouring sequences. Some of the evidence supporting the incorporation of foreign DNA is as follows: a partial deletion in a second 3'-CS (3'-CS2), and the absence of 59-base element or IS-like structures upstream of bla(CTX-M-2).