Scientific Commons: Timothy R. Walsh

The current β-lactamase classifications have reached a high level of complexity, making them less accessible to clinicians, infection control professionals, hospital management and politicians. From...

Emergence and persistence of integron structures harbouring VIM genes in the Children's Memorial Health Institute, Warsaw, Poland, 1998-2006 (2009)

Patzer, Jan A., Walsh, Timothy R., Weeks, Janis, Dzierzanowska, Danuta, Toleman, Mark A.

Objectives The aim was to perform a genetically detailed study of the emergence of metallo-β-lactamase (MBL) genes in Pseudomonas spp. in the Children's Memorial Health Institute over a 9 year...

Counting Unrooted Loopless Planar Maps (2008)

Séries Formelles, Combinatoire Algébrique, Valery A. Liskovets, Timothy R. Walsh

Abstract. We present a formula for the number of n-edge unrooted loopless planar maps considered up to orientation-preserving isomorphism. The only sum contained in this formula is over the divisors...

The AmpC phenotype in Norwegian clinical isolates of Escherichia coli is associated with an acquired ISEcp1-like ampC element or hyperproduction of the endogenous AmpC (2008)

Haldorsen, Bjørg, Aasnaes, Bettina, Dahl, Kristin H., Hanssen, Anne-Merethe, Simonsen, Gunnar S., Walsh, Timothy R., ...

Objectives The aim of the study was to examine resistance mechanisms associated with an AmpC phenotype in Norwegian clinical isolates of Escherichia coli. Methods Clinical E. coli isolates (n = 106)...

Characterization of Monomeric L1 Metallo-�-lactamase and the Role (2007)

Alan M. Simm, Catherine S. Higgins, Anne L. Carenbauer, Michael W. Crowder, John H. Bateson, Peter M. Bennett, ...

maltophilia is unique among this class of enzymes because it is tetrameric. Previous work predicted that the two regions of important intersubunit interaction were the residue Met-140 and the...

A multi-center blinded study on the efficiency of phenotypic screening methods to detect glycopeptide intermediately susceptible Staphylococcus aureus(GISA) and heterogeneous GISA (h-GISA) (2007)

Voss, Andreas, Mouton, Johan W, Van Elzakker, Erika P, Hendrix, Ron G, Goessens, Wil, Kluytmans, Jan A, ...

Abstract Backgrounds To determine the true incidence of hGISA/GISA and its consequent clinical impact, methods must be defined that will reliably and reproducibly discriminate these resistant...

Common regions e.g. orf513 and antibiotic resistance: IS91-like elements evolving complex class 1 integrons (2006)

Toleman, Mark A., Bennett, Peter M., Walsh, Timothy R.

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...

Common regions e.g. orf513 and antibiotic resistance: IS91-like elements evolving complex class 1 integrons (2006)

Toleman, Mark A., Bennett, Peter M., Walsh, Timothy R.

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...

Reduced expression of the atl autolysin gene and susceptibility to autolysis in clinical heterogeneous glycopeptide-intermediate Staphylococcus aureus (hGISA) and GISA strains (2005)

Wootton, Mandy, Bennett, Peter M., MacGowan, Alasdair P., Walsh, Timothy R.

Objectives: To assess a link between resistance to Triton X-100 induced autolysis (TIA) and lowered atl expression in a collection of clinical glycopeptide-intermediate Staphylococcus aureus (GISA)...

Italian metallo-{beta}-lactamases: a national problem? Report from the SENTRY Antimicrobial Surveillance Programme (2005)

Toleman, Mark A., Biedenbach, Doug, Bennett, David M. C., Jones, Ronald N., Walsh, Timothy R.

Objectives: As part of the SENTRY Antimicrobial Surveillance Programme, 383 non-replicative randomly collected Pseudomonas aeruginosa isolates were collected during 1999–2002. These strains...

Reduced expression of the atl autolysin gene and susceptibility to autolysis in clinical heterogeneous glycopeptide-intermediate Staphylococcus aureus (hGISA) and GISA strains (2005)

Wootton, Mandy, Bennett, Peter M., MacGowan, Alasdair P., Walsh, Timothy R.

Objectives: To assess a link between resistance to Triton X-100 induced autolysis (TIA) and lowered atl expression in a collection of clinical glycopeptide-intermediate Staphylococcus aureus (GISA)...

Role of the 'cre/blr-tag' DNA sequence in regulation of gene expression by the Aeromonas hydrophila {beta}-lactamase regulator, BlrA (2004)

Avison, Matthew B., Niumsup, Pannika, Nurmahomed, Kurshid, Walsh, Timothy R., Bennett, Peter M.

Objectives: To further understand the mechanisms used to regulate expression of the blr regulon of Aeromonas hydrophila T429125, including three unlinked β-lactamase genes, ampH, cepH and imiH, and...

Pseudomonas aeruginosa strains harbouring an unusual blaVIM-4 gene cassette isolated from hospitalized children in Poland (1998-2001) (2004)

Patzer, Jan, Toleman, Mark A., Deshpande, Lalitagauri M., Kamiska, Wanda, Dzieranowska, Danuta, Bennett, Peter M., ...

Objectives: During 1997-2001, 151 isolates of imipenem-resistant Pseudomonas aeruginosa were obtained from clinical specimens taken from children hospitalized in Warsaw, Poland. These strains were...

Analysis of AmpC {beta}-lactamase expression and sequence in biochemically atypical ceftazidime-resistant Enterobacteriaceae from paediatric patients (2004)

Avison, Matthew B., Underwood, Sarah, Okazaki, Aki, Walsh, Timothy R., Bennett, Peter M.

Objectives: To analyse the variation of ampC β-lactamase gene sequence and expression in biochemically atypical Enterobacteriaceae isolates, and to identify them definitively. Methods: β-Lactamase...

Italian metallo-{beta}-lactamases: a national problem? Report from the SENTRY Antimicrobial Surveillance Programme (2004)

Toleman, Mark A., Biedenbach, Doug, Bennett, David M. C., Jones, Ronald N., Walsh, Timothy R.

Objectives: As part of the SENTRY Antimicrobial Surveillance Programme, 383 non-replicative randomly collected Pseudomonas aeruginosa isolates were collected during 1999-2002. These strains...

Role of the 'cre/blr-tag' DNA sequence in regulation of gene expression by the Aeromonas hydrophila {beta}-lactamase regulator, BlrA (2004)

Avison, Matthew B., Niumsup, Pannika, Nurmahomed, Kurshid, Walsh, Timothy R., Bennett, Peter M.

Objectives: To further understand the mechanisms used to regulate expression of the blr regulon of Aeromonas hydrophila T429125, including three unlinked &bgr;-lactamase genes, ampH, cepH and imiH,...

Pseudomonas aeruginosa strains harbouring an unusual blaVIM-4 gene cassette isolated from hospitalized children in Poland (1998-2001) (2004)

Patzer, Jan, Toleman, Mark A., Deshpande, Lalitagauri M., Kaminska, Wanda, Dzierzanowska, Danuta, Bennett, Peter M., ...

Objectives: During 1997–2001, 151 isolates of imipenem-resistant Pseudomonas aeruginosa were obtained from clinical specimens taken from children hospitalized in Warsaw, Poland. These strains were...

Analysis of AmpC {beta}-lactamase expression and sequence in biochemically atypical ceftazidime-resistant Enterobacteriaceae from paediatric patients (2004)

Avison, Matthew B., Underwood, Sarah, Okazaki, Aki, Walsh, Timothy R., Bennett, Peter M.

Objectives: To analyse the variation of ampC &bgr;-lactamase gene sequence and expression in biochemically atypical Enterobacteriaceae isolates, and to identify them definitively. Methods:...

Evolution of an integron carrying blaVIM-2 in Eastern Europe: report from the SENTRY Antimicrobial Surveillance Program (2003)

Walsh, Timothy R., Toleman, Mark A., Hryniewicz, Waleria, Bennett, Peter M., Jones, Ronald N.

As part of the SENTRY Antimicrobial Surveillance Program, an imipenem-resistant Pseudomonas aeruginosa strain (81-11963A) was isolated from the blood culture of a female neonate institutionalized at...

Genetic linkage of the penicillinase gene, amp, and blrAB, encoding the regulator of {beta}-lactamase expression in Aeromonas spp. (2003)

Niumsup, Pannika, Simm, Alan M., Nurmahomed, Kurshid, Walsh, Timothy R., Bennett, Peter M., Avison, Matthew B.

Aeromonas hydrophila T429125, a human clinical isolate, possesses three coordinately inducible &bgr;-lactamases encoded by ampH (class D &bgr;-lactamase), cepH (class C &bgr;-lactamase) and imiH...

Genetic linkage of the penicillinase gene, amp, and blrAB, encoding the regulator of {beta}-lactamase expression in Aeromonas spp (2003)

Niumsup, Pannika, Simm, Alan M., Nurmahomed, Kurshid, Walsh, Timothy R., Bennett, Peter M., Avison, Matthew B.

Aeromonas hydrophila T429125, a human clinical isolate, possesses three coordinately inducible β-lactamases encoded by ampH (class D β-lactamase), cepH (class C β-lactamase) and imiH (class B...

Evolution of an integron carrying blaVIM-2 in Eastern Europe: report from the SENTRY Antimicrobial Surveillance Program (2003)

Walsh, Timothy R., Toleman, Mark A., Hryniewicz, Waleria, Bennett, Peter M., Jones, Ronald N.

As part of the SENTRY Antimicrobial Surveillance Program, an imipenem-resistant Pseudomonas aeruginosa strain (81-11963A) was isolated from the blood culture of a female neonate institutionalized at...

Genetic characterization of a novel metallo-{beta}-lactamase gene, blaIMP-13, harboured by a novel Tn5051-type transposon disseminating carbapenemase genes in Europe: report from the SENTRY worldwide antimicrobial surveillance programme (2003)

Toleman, Mark A., Biedenbach, Doug, Bennett, David, Jones, Ronald N., Walsh, Timothy R.

Objective: In 2001, as part of the SENTRY worldwide antimicrobial surveillance programme, Pseudomonas aeruginosa 86-14571A was isolated at a hospital in Rome from a cancer patient with a bloodstream...

Genetic characterization of a novel metallo-{beta}-lactamase gene, blaIMP-13, harboured by a novel Tn5051-type transposon disseminating carbapenemase genes in Europe: report from the SENTRY worldwide antimicrobial surveillance programme (2003)

Toleman, Mark A., Biedenbach, Doug, Bennett, David, Jones, Ronald N., Walsh, Timothy R.

Objective: In 2001, as part of the SENTRY worldwide antimicrobial surveillance programme, Pseudomonas aeruginosa 86–14571A was isolated at a hospital in Rome from a cancer patient with a...

Genetic linkage of the penicillinase gene, amp, and blrAB, encoding the regulator of {beta}-lactamase expression in Aeromonas spp (2003)

Niumsup, Pannika, Simm, Alan M., Nurmahomed, Kurshid, Walsh, Timothy R., Bennett, Peter M., Avison, Matthew B.

Aeromonas hydrophila T429125, a human clinical isolate, possesses three coordinately inducible β-lactamases encoded by ampH (class D β-lactamase), cepH (class C β-lactamase) and imiH (class B...

Evolution of an integron carrying blaVIM-2 in Eastern Europe: report from the SENTRY Antimicrobial Surveillance Program (2003)

Walsh, Timothy R., Toleman, Mark A., Hryniewicz, Waleria, Bennett, Peter M., Jones, Ronald N.

As part of the SENTRY Antimicrobial Surveillance Program, an imipenem-resistant Pseudomonas aeruginosa strain (81-11963A) was isolated from the blood culture of a female neonate institutionalized at...

Genetic characterization of a novel metallo-{beta}-lactamase gene, blaIMP-13, harboured by a novel Tn5051-type transposon disseminating carbapenemase genes in Europe: report from the SENTRY worldwide antimicrobial surveillance programme (2003)

Toleman, Mark A., Biedenbach, Doug, Bennett, David, Jones, Ronald N., Walsh, Timothy R.

Objective: In 2001, as part of the SENTRY worldwide antimicrobial surveillance programme, Pseudomonas aeruginosa 86-14571A was isolated at a hospital in Rome from a cancer patient with a bloodstream...

Preliminary analysis of the genetic basis for vancomycin resistance in Staphylococcus aureus strain Mu50 (2002)

Avison, Matthew B., Bennett, Peter M., Howe, Robin A., Walsh, Timothy R.

Glycopeptides, such as vancomycin, are frequently the antibiotics of choice for treatment of infections caused by the now common methicillin-resistant Staphylococcus aureus (MRSA). Incidences of...

Differential regulation of L1 and L2 {beta}-lactamase expression in Stenotrophomonas maltophilia (2002)

Avison, Matthew B., Higgins, Catherine S., Ford, Peter J., Von Heldreich, Charlotte J., Walsh, Timothy R., Bennett, Peter M.

It has been reported that Stenotrophomonas maltophilia L1 and L2 β-lactamase expression is coordinated. We have isolated S. maltophilia mutants where (i) L1 is constitutively hyper-expressed and L2...

Molecular characterization of SPM-1, a novel metallo-{beta}-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme (2002)

Toleman, Mark A., Simm, Alan M., Murphy, Tanya A., Gales, Ana C., Biedenbach, Doug J., Jones, Ronald N., ...

The gene encoding the metallo-ß-lactamase SPM-1 was cloned from a genomic library of Pseudomonas aeruginosa strain 48-1997A. The insert carrying spm-1 possessed a GC content of 47%, indicating that...

Molecular characterization of SPM-1, a novel metallo-{beta}-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme (2002)

Toleman, Mark A., Simm, Alan M., Murphy, Tanya A., Gales, Ana C., Biedenbach, Doug J., Jones, Ronald N., ...

The gene encoding the metallo-&bgr;-lactamase SPM-1 was cloned from a genomic library of Pseudomonas aeruginosa strain 48-1997A. The insert carrying spm-1 possessed a GC content of 47%,...

Molecular characterization of SPM-1, a novel metallo-{beta}-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme (2002)

Toleman, Mark A., Simm, Alan M., Murphy, Tanya A., Gales, Ana C., Biedenbach, Doug J., Jones, Ronald N., ...

The gene encoding the metallo-ß-lactamase SPM-1 was cloned from a genomic library of Pseudomonas aeruginosa strain 48-1997A. The insert carrying spm-1 possessed a GC content of 47%, indicating that...

The activity of vancomycin against heterogeneous vancomycin-intermediate methicillin-resistant Staphylococcus aureus explored using an in vitro pharmacokinetic model (2001)

Turner, Jonathan, Howe, Robin A., Wootton, Mandy, Bowker, Karen E., Holt, H. Alan, Salisbury, Vyvyan, ...

Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) may account for treatment failure with vancomycin and act as a precursor of vancomycin-intermediate or -resistant S. aureus. The...

Characterization, cloning and sequence analysis of the inducible Ochrobactrum anthropi AmpC {beta}-lactamase (2001)

Higgins, Catherine S., Avison, Matthew B., Jamieson, Lee, Simm, Alan M., Bennett, Peter M., Walsh, Timothy R.

Ochrobactrum anthropi is resistant to most cephalosporins and penicillins due, at least in part, to the inducible expression of a single β-lactamase. The β-lactamase gene has been cloned and...

A TEM-2 {beta}-lactamase encoded on an active Tn1-like transposon in the genome of a clinical isolate of Stenotrophomonas maltophilia (2000)

Avison, Matthew B., Von Heldreich, Charlotte J., Higgins, Catherine S., Bennett, Peter M., Walsh, Timothy R.

A constitutively expressed β-lactamase gene from a clinical isolate of Stenotrophomonas maltophilia, J675Ia, has been cloned. Its DNA sequence is almost identical to that of blaTEM2 (one nucleotide...

{beta}-Lactamase expression in Plesiomonas shigelloides (2000)

Avison, Matthew B., Bennett, Peter M., Walsh, Timothy R.

We have examined the production of β-lactamases by 11 clinical and nine environmental isolates of Plesiomonas shigelloides from Czechoslovakia, the Czech Republic and Cuba. Ten isolates (50%)...

Heterogeneous resistance to vancomycin in Staphylococcus aureus (2000)

Howe, Robin A., Wootton, Mandy, Walsh, Timothy R., Bennett, Peter M., Macgowan, Alasdair P.

Aeromonas hydrophila AmpH and CepH {beta}-lactamases: derepressed expression in mutants of Escherichia coli lacking creB (2000)

Avison, Matthew B., Niumsup, Pannika, Walsh, Timothy R., Bennett, Peter M.

The class 1 cephalosporinase (CepH) and class 2d oxacillinase (AmpH) from an Aeromonas hydrophila clinical isolate, strain T429125, have been cloned and sequenced. Both enzymes are typical of their...

Molecular Bacteriology: Protocols and Clinical Application (1999)

Walsh, Timothy R.

Antibacterial Peptide Protocols (Methods in Molecular Biology Volume 78) (1999)

Walsh, Timothy R.

Expression and detection of hetero-vancomycin resistance in Staphylococcus aureus (1999)

Howe, Robin A., Wootton, Mandy, Walsh, Timothy R., Bennett, Peter M., MacGowan, Alasdair P.

Isolates of Staphylococcus aureus resistant to vancomycin have been reported but appear to be extremely rare. However, isolates displaying hetero-resistance to vancomycin (hVRSA) are reportedly...

Enzyme kinetics and biochemical analysis of ImiS, the metallo-{beta}-lactamase from Aeromonas sobria 163a (1996)

Walsh, Timothy R., Gamblin, Steven, Emery, David C., MacGowan, Alasdair P., Bennett, Peter M.

The metallo-β-lactamase from Aeromonas sobria 163a, ImiS, was isolated in a two stage purification procedure using protein affinity columns. Enzyme kinetics show that ImiS hydrolyses the carbapenems...

A clinical isolate of Aeromonas sobria with three chromosomally mediated inducible {beta}-lactamases: a cephalosporinase, a penicillinase and a third enzyme, displaying carbapenemase activity (1995)

Walsh, Timothy R., Payne, David J., MacGowan, Alasdair P., Bennett, Peter M.

Hydrolytic profiles of Aeromonas sobria 163a, non-induced and induced, and of a derepressed mutant 163a-M, indicate that this strain has inducible β-lactamases with activities against...

Sequence analysis of two chromosomally mediated inducible {beta}-lactamases from Aeromonas sobria, strain 163a, one a class D penicillinase, the other an AmpC cephalosporinase (1995)

Walsh, Timothy R., Hall, Len, MacGowan, Alasdair P., Bennett, Peter M.

Two β-lactamase genes from Aeromonas sobria, strain 163a, have been cloned and sequenced, one encoding a typical class C cephalosporinase, designated CepS, the other a class D penicillinase,...

Interactions between Methicillin and Vancomycin in Methicillin-Resistant Staphylococcus aureus Strains Displaying Different Phenotypes of Vancomycin Susceptibility

Howe, Robin A., Wootton, Mandy, Bennett, Peter M., MacGowan, Alasdair P., Walsh, Timothy R.

Vancomycin-sensitive, -intermediate, and -heterointermediate methicillin-resistant Staphylococcus aureus isolates were tested by using E-tests to explore the interaction of methicillin and...

Evaluation of Current Methods for Detection of Staphylococci with Reduced Susceptibility to Glycopeptides

Walsh, Timothy R., Bolmström, Anne, Qwärnström, Anette, Ho, Phion, Wootton, Mandy, Howe, Robin A., ...

The sensitivity and specificity of seven methods (agar dilution, broth microdilution, Etest at 0.5 and 2.0 McFarland (McF) inocula, two agar screening methods, and population studies [PS]) were...

Plasmid Location and Molecular Heterogeneity of the L1 and L2 β-Lactamase Genes of Stenotrophomonas maltophilia

Avison, Matthew B., Higgins, Catherine S., Von Heldreich, Charlotte J., Bennett, Peter M., Walsh, Timothy R.

An approximately 200-kb plasmid has been purified from clinical isolates of Stenotrophomonas maltophilia. This plasmid was found in all of the 10 isolates examined and contains both the L1 and the L2...

Overexpression, Purification, and Characterization of the Cloned Metallo-β-Lactamase L1 from Stenotrophomonas maltophilia

Crowder, Michael W., Walsh, Timothy R., Banovic, Linda, Pettit, Margaret, Spencer, James

The metallo-β-lactamase L1 from Stenotrophomonas maltophilia was cloned, overexpressed, and characterized by spectrometric and biochemical techniques. Results of metal analyses were consistent with...

Evaluation of a New Etest for Detecting Metallo-β-Lactamases in Routine Clinical Testing

Walsh, Timothy R., Bolmström, Anne, Qwärnström, Anette, Gales, Ana

Several Etest (AB BIODISK, Solna, Sweden) gradient formats were developed for detection of metallo-β-lactamases based on the reduction of imipenem (IP) or ceftazidime (TZ) MICs in the presence of...

Biochemical Characterization of the Acquired Metallo-β-Lactamase SPM-1 from Pseudomonas aeruginosa

Murphy, Tanya A., Simm, Alan M., Toleman, Mark A., Jones, Ronald N., Walsh, Timothy R.

SPM-1 is a new metallo-β-lactamase recently identified in Pseudomonas aeruginosa strain 48-1997A, isolated in Sao Paulo, Brazil. Kinetic analysis demonstrated that SPM-1 has a broad hydrolytic...

Molecular and Biochemical Characterization of OXA-45, an Extended-Spectrum Class 2d′ β-Lactamase in Pseudomonas aeruginosa

Toleman, Mark A., Rolston, Kenneth, Jones, Ronald N., Walsh, Timothy R.

As part of the CANCER Antimicrobial Surveillance Program in North America, a clinical strain of Pseudomonas aeruginosa, strain 07-406, isolated in Texas was found to be resistant to all...

Activity of AZD2563, a Novel Oxazolidinone, against Staphylococcus aureus Strains with Reduced Susceptibility to Vancomycin or Linezolid

Howe, Robin A., Wootton, Mandy, Noel, Alan R., Bowker, Karen E., Walsh, Timothy R., MacGowan, Alasdair P.

The susceptibilities of clinical vancomycin-intermediate Staphylococcus aureus (VISA), heterogenous VISA, and laboratory-generated linezolid-resistant S. aureus strains to the new oxazolidinone...

blaVIM-7, an Evolutionarily Distinct Metallo-β-Lactamase Gene in a Pseudomonas aeruginosa Isolate from the United States

Toleman, Mark A., Rolston, Kenneth, Jones, Ronald N., Walsh, Timothy R.

As part of the CANCER Antimicrobial Surveillance Program in North America, a Pseudomonas aeruginosa isolate, strain 07-406, was shown to possess a metallo-β-lactamase, designated VIM-7. blaVIM-7 is...

Antimicrobial Susceptibility and Epidemiology of a Worldwide Collection of Chryseobacterium spp.: Report from the SENTRY Antimicrobial Surveillance Program (1997-2001)

Kirby, Jeffrey T., Sader, Helio S., Walsh, Timothy R., Jones, Ronald N.

Limited data are available on Chryseobacterium spp. leading to an evaluation of the patient demographics and susceptibility patterns for Chryseobacterium spp. collected in the first 5 years of the...

First Isolation of blaVIM-2 in Latin America: Report from the SENTRY Antimicrobial Surveillance Program

Mendes, Rodrigo E., Castanheira, Mariana, Garcia, Patricia, Guzman, Manuel, Toleman, Mark A., Walsh, Timothy R., ...

Emergence of the Extended-Spectrum β-Lactamase GES-1 in a Pseudomonas aeruginosa Strain from Brazil: Report from the SENTRY Antimicrobial Surveillance Program

Castanheira, Mariana, Mendes, Rodrigo E., Walsh, Timothy R., Gales, Ana C., Jones, Ronald N.

Pharmacodynamics of Ceftazidime plus the Serine β-Lactamase Inhibitor AM-112 against Escherichia coli Containing TEM-1 and CTX-M-1 β-Lactamases

Bowker, Karen E., Noel, Alan R., Walsh, Timothy R., Rogers, Chris A., MacGowan, Alasdair P.

A strain of Escherichia coli containing TEM-1 and CTX-M-1 was tested in an in vitro pharmacokinetic model against ceftazidime with and without AM-112, a serine β-lactamase inhibitor. Ceftazidime...

Molecular Characterization of a β-Lactamase Gene, blaGIM-1, Encoding a New Subclass of Metallo-β-Lactamase

Castanheira, Mariana, Toleman, Mark A., Jones, Ronald N., Schmidt, Franz J., Walsh, Timothy R.

As part of the SENTRY Antimicrobial Surveillance Program in 2002, five multidrug-resistant Pseudomonas aeruginosa clinical isolates were detected with metallo-β-lactamase (MβL) activity. The...

Integron Carrying a Novel Metallo-β-Lactamase Gene, blaIMP-16, and a Fused Form of Aminoglycoside-Resistant Gene aac(6′)-30/aac(6′)-Ib′: Report from the SENTRY Antimicrobial Surveillance Program

Mendes, Rodrigo E., Toleman, Mark A., Ribeiro, Julival, Sader, Helio S., Jones, Ronald N., Walsh, Timothy R.

Since January 2002 Pseudomonas sp. strains resistant to carbapenems and ceftazidime have been routinely screened as part of the SENTRY Antimicrobial Surveillance Program for metallo-β-lactamase...

Functional Characterization of OXA-57, a Class D β-Lactamase from Burkholderia pseudomallei

Keith, Karen E., Oyston, Petra C., Crossett, Ben, Fairweather, Neil F., Titball, Richard W., Walsh, Timothy R., ...

Class D β-lactamase OXA-57 was identified in a range of isolates of Burkholderia pseudomallei and Burkholderia thailandensis. Comparative kinetic analyses of wild-type and mutant forms of B....

Metallo-β-Lactamases: the Quiet before the Storm?

Walsh, Timothy R., Toleman, Mark A., Poirel, Laurent, Nordmann, Patrice

The ascendancy of metallo-β-lactamases within the clinical sector, while not ubiquitous, has nonetheless been dramatic; some reports indicate that nearly 30% of imipenem-resistant Pseudomonas...

Interactions between Methicillin and Vancomycin in Methicillin-Resistant Staphylococcus aureus Strains Displaying Different Phenotypes of Vancomycin Susceptibility

Howe, Robin A., Wootton, Mandy, Bennett, Peter M., MacGowan, Alasdair P., Walsh, Timothy R.

Vancomycin-sensitive, -intermediate, and -heterointermediate methicillin-resistant Staphylococcus aureus isolates were tested by using E-tests to explore the interaction of methicillin and...

Evaluation of Current Methods for Detection of Staphylococci with Reduced Susceptibility to Glycopeptides

Walsh, Timothy R., Bolmström, Anne, Qwärnström, Anette, Ho, Phion, Wootton, Mandy, Howe, Robin A., ...

The sensitivity and specificity of seven methods (agar dilution, broth microdilution, Etest at 0.5 and 2.0 McFarland (McF) inocula, two agar screening methods, and population studies [PS]) were...

Plasmid Location and Molecular Heterogeneity of the L1 and L2 β-Lactamase Genes of Stenotrophomonas maltophilia

Avison, Matthew B., Higgins, Catherine S., Von Heldreich, Charlotte J., Bennett, Peter M., Walsh, Timothy R.

An approximately 200-kb plasmid has been purified from clinical isolates of Stenotrophomonas maltophilia. This plasmid was found in all of the 10 isolates examined and contains both the L1 and the L2...

Overexpression, Purification, and Characterization of the Cloned Metallo-β-Lactamase L1 from Stenotrophomonas maltophilia

Crowder, Michael W., Walsh, Timothy R., Banovic, Linda, Pettit, Margaret, Spencer, James

The metallo-β-lactamase L1 from Stenotrophomonas maltophilia was cloned, overexpressed, and characterized by spectrometric and biochemical techniques. Results of metal analyses were consistent with...

Evaluation of a New Etest for Detecting Metallo-β-Lactamases in Routine Clinical Testing

Walsh, Timothy R., Bolmström, Anne, Qwärnström, Anette, Gales, Ana

Several Etest (AB BIODISK, Solna, Sweden) gradient formats were developed for detection of metallo-β-lactamases based on the reduction of imipenem (IP) or ceftazidime (TZ) MICs in the presence of...

Biochemical Characterization of the Acquired Metallo-β-Lactamase SPM-1 from Pseudomonas aeruginosa

Murphy, Tanya A., Simm, Alan M., Toleman, Mark A., Jones, Ronald N., Walsh, Timothy R.

SPM-1 is a new metallo-β-lactamase recently identified in Pseudomonas aeruginosa strain 48-1997A, isolated in Sao Paulo, Brazil. Kinetic analysis demonstrated that SPM-1 has a broad hydrolytic...

Molecular and Biochemical Characterization of OXA-45, an Extended-Spectrum Class 2d′ β-Lactamase in Pseudomonas aeruginosa

Toleman, Mark A., Rolston, Kenneth, Jones, Ronald N., Walsh, Timothy R.

As part of the CANCER Antimicrobial Surveillance Program in North America, a clinical strain of Pseudomonas aeruginosa, strain 07-406, isolated in Texas was found to be resistant to all...

Activity of AZD2563, a Novel Oxazolidinone, against Staphylococcus aureus Strains with Reduced Susceptibility to Vancomycin or Linezolid

Howe, Robin A., Wootton, Mandy, Noel, Alan R., Bowker, Karen E., Walsh, Timothy R., MacGowan, Alasdair P.

The susceptibilities of clinical vancomycin-intermediate Staphylococcus aureus (VISA), heterogenous VISA, and laboratory-generated linezolid-resistant S. aureus strains to the new oxazolidinone...

blaVIM-7, an Evolutionarily Distinct Metallo-β-Lactamase Gene in a Pseudomonas aeruginosa Isolate from the United States

Toleman, Mark A., Rolston, Kenneth, Jones, Ronald N., Walsh, Timothy R.

As part of the CANCER Antimicrobial Surveillance Program in North America, a Pseudomonas aeruginosa isolate, strain 07-406, was shown to possess a metallo-β-lactamase, designated VIM-7. blaVIM-7 is...

Antimicrobial Susceptibility and Epidemiology of a Worldwide Collection of Chryseobacterium spp.: Report from the SENTRY Antimicrobial Surveillance Program (1997-2001)

Kirby, Jeffrey T., Sader, Helio S., Walsh, Timothy R., Jones, Ronald N.

Limited data are available on Chryseobacterium spp. leading to an evaluation of the patient demographics and susceptibility patterns for Chryseobacterium spp. collected in the first 5 years of the...

First Isolation of blaVIM-2 in Latin America: Report from the SENTRY Antimicrobial Surveillance Program

Mendes, Rodrigo E., Castanheira, Mariana, Garcia, Patricia, Guzman, Manuel, Toleman, Mark A., Walsh, Timothy R., ...

Emergence of the Extended-Spectrum β-Lactamase GES-1 in a Pseudomonas aeruginosa Strain from Brazil: Report from the SENTRY Antimicrobial Surveillance Program

Castanheira, Mariana, Mendes, Rodrigo E., Walsh, Timothy R., Gales, Ana C., Jones, Ronald N.

Pharmacodynamics of Ceftazidime plus the Serine β-Lactamase Inhibitor AM-112 against Escherichia coli Containing TEM-1 and CTX-M-1 β-Lactamases

Bowker, Karen E., Noel, Alan R., Walsh, Timothy R., Rogers, Chris A., MacGowan, Alasdair P.

A strain of Escherichia coli containing TEM-1 and CTX-M-1 was tested in an in vitro pharmacokinetic model against ceftazidime with and without AM-112, a serine β-lactamase inhibitor. Ceftazidime...

Molecular Characterization of a β-Lactamase Gene, blaGIM-1, Encoding a New Subclass of Metallo-β-Lactamase

Castanheira, Mariana, Toleman, Mark A., Jones, Ronald N., Schmidt, Franz J., Walsh, Timothy R.

As part of the SENTRY Antimicrobial Surveillance Program in 2002, five multidrug-resistant Pseudomonas aeruginosa clinical isolates were detected with metallo-β-lactamase (MβL) activity. The...

Integron Carrying a Novel Metallo-β-Lactamase Gene, blaIMP-16, and a Fused Form of Aminoglycoside-Resistant Gene aac(6′)-30/aac(6′)-Ib′: Report from the SENTRY Antimicrobial Surveillance Program

Mendes, Rodrigo E., Toleman, Mark A., Ribeiro, Julival, Sader, Helio S., Jones, Ronald N., Walsh, Timothy R.

Since January 2002 Pseudomonas sp. strains resistant to carbapenems and ceftazidime have been routinely screened as part of the SENTRY Antimicrobial Surveillance Program for metallo-β-lactamase...

Functional Characterization of OXA-57, a Class D β-Lactamase from Burkholderia pseudomallei

Keith, Karen E., Oyston, Petra C., Crossett, Ben, Fairweather, Neil F., Titball, Richard W., Walsh, Timothy R., ...

Class D β-lactamase OXA-57 was identified in a range of isolates of Burkholderia pseudomallei and Burkholderia thailandensis. Comparative kinetic analyses of wild-type and mutant forms of B....

Metallo-β-Lactamases: the Quiet before the Storm?

Walsh, Timothy R., Toleman, Mark A., Poirel, Laurent, Nordmann, Patrice

The ascendancy of metallo-β-lactamases within the clinical sector, while not ubiquitous, has nonetheless been dramatic; some reports indicate that nearly 30% of imipenem-resistant Pseudomonas...

Integrons Containing the VIM-2 Metallo-β-Lactamase Gene among Imipenem-Resistant Pseudomonas aeruginosa Strains from Different Chinese Hospitals▿

Yu, Yun-Song, Qu, Ting-Ting, Zhou, Jian-Ying, Wang, Jie, Li, Hong-Yang, Walsh, Timothy R.

A total of 140 nonrepetitive strains of imipenem-resistant Pseudomonas aeruginosa were isolated from five different Chinese hospitals. Fourteen isolates were confirmed to contain the VIM-2...

Comparative Bactericidal Activities of Daptomycin and Vancomycin against Glycopeptide-Intermediate Staphylococcus aureus (GISA) and Heterogeneous GISA Isolates▿

Wootton, Mandy, MacGowan, Alasdair P., Walsh, Timothy R.

Staphylococcus aureus strains from the U.S. SENTRY Antimicrobial Surveillance Program, 2002-2003, glycopeptide-intermediate S. aureus (GISA) strains, and heterogeneous GISA (hGISA) strains were used...

Effects of Phenotype and Genotype on Methods for Detection of Extended-Spectrum-β-Lactamase-Producing Clinical Isolates of Escherichia coli and Klebsiella pneumoniae in Norway▿

Tofteland, Ståle, Haldorsen, Bjørg, Dahl, Kristin H., Simonsen, Gunnar S., Steinbakk, Martin, Walsh, Timothy R., ...

Consecutive clinical isolates of Escherichia coli (n = 87) and Klebsiella pneumoniae (n = 25) with reduced susceptibilities to oxyimino-cephalosporins (MICs > 1 mg/liter) from 18 Norwegian...

ISCR Elements: Novel Gene-Capturing Systems of the 21st Century?

Toleman, Mark A., Bennett, Peter M., Walsh, Timothy R.

“Common regions” (CRs), such as Orf513, are being increasingly linked to mega-antibiotic-resistant regions. While their overall nucleotide sequences show little identity to other mobile elements,...

A Multicenter Study Evaluating the Current Strategies for Isolating Staphylococcus aureus Strains with Reduced Susceptibility to Glycopeptides▿

Wootton, Mandy, MacGowan, Alasdair P., Walsh, Timothy R., Howe, Robin A.

Glycopeptide-intermediate Staphylococcus aureus (GISA) and heterogeneous GISA (hGISA) strains are notoriously difficult to detect in the diagnostic laboratory. The clinical importance of GISA, and...

A multi-center blinded study on the efficiency of phenotypic screening methods to detect glycopeptide intermediately susceptible Staphylococcus aureus (GISA) and heterogeneous GISA (h-GISA)

Voss, Andreas, Mouton, Johan W, Van Elzakker, Erika P, Hendrix, Ron G, Goessens, Wil, Kluytmans, Jan A, ...

Characterization of an Integron Carrying blaIMP-1 and a New Aminoglycoside Resistance Gene, aac(6′)-31, and Its Dissemination among Genetically Unrelated Clinical Isolates in a Brazilian Hospital▿

Mendes, Rodrigo E., Castanheira, Mariana, Toleman, Mark A., Sader, Helio S., Jones, Ronald N., Walsh, Timothy R.

Seven blaIMP-1-harboring Acinetobacter sp. isolates and one Pseudomonas putida clinical isolate were recovered from hospitalized patients. All isolates possessed a class 1 integron, named In86,...

blaVIM-2-Harboring Integrons Isolated in India, Russia, and the United States Arise from an Ancestral Class 1 Integron Predating the Formation of the 3′ Conserved Sequence▿

Toleman, Mark A., Vinodh, Hemalatha, Sekar, Uma, Kamat, Vijaylakshmi, Walsh, Timothy R.

The metallo-β-lactamase gene blaVIM-2 was identified in a strain of Pseudomonas aeruginosa isolated in India. The integron encoding blaVIM-2 was virtually identical to those recently found in the...

Dissemination of CTX-M-15 β-Lactamase Genes Carried on Inc FI and FII Plasmids among Clinical Isolates of Escherichia coli in a University Hospital in Istanbul, Turkey▿

Gonullu, Nevriye, Aktas, Zerrin, Kayacan, Cigdem Bal, Salcioglu, Melek, Carattoli, Alessandra, Yong, Dong Eun, ...

The CTX-M-1 group was found in 86.8% of the Escherichia coli isolates from Istanbul. A subset study revealed all isolates carrying blaCTX-M-15 genes flanked by the insertion element ISEcp1. Plasmid...

Kinetic Characterization of VIM-7, a Divergent Member of the VIM Metallo-β-Lactamase Family▿

Samuelsen, Ørjan, Castanheira, Mariana, Walsh, Timothy R., Spencer, James

Purified recombinant VIM-7 possesses efficient penicillinase and carbapenemase activities comparable to those of VIM-2. Cephalosporinase activity was variable and generally lower than those of VIM-1...

Complete Sequence of p07-406, a 24,179-Base-Pair Plasmid Harboring the blaVIM-7 Metallo-β-Lactamase Gene in a Pseudomonas aeruginosa Isolate from the United States▿

Li, Hongyang, Toleman, Mark A., Bennett, Peter M., Jones, Ronald N., Walsh, Timothy R.

An outbreak involving a Pseudomonas aeruginosa strain that was resistant to all tested antimicrobials except polymyxin B occurred in a hospital in Houston, TX. Previous studies on this strain showed...

Evaluation of a New Etest Vancomycin-Teicoplanin Strip for Detection of Glycopeptide-Intermediate Staphylococcus aureus (GISA), in Particular, Heterogeneous GISA▿

Yusof, Anne, Engelhardt, Anette, Karlsson, Åsa, Bylund, Lina, Vidh, Pamela, Mills, Karen, ...

Glycopeptide-intermediate Staphylococcus aureus (GISA) and, in particular, heterogeneous GISA (hGISA) are difficult to detect by standard MIC methods, and thus, an accurate detection method for...

Evolution of the ISCR3 Group of ISCR Elements▿

Toleman, Mark A., Walsh, Timothy R.

The ISCR elements ISCR3, ISCR4, ISCR5, ISCR14, and ISCR16 all share a percent G+C of 68 to 69%. They also share between 75% and 97% identity in their transposase open reading frames. Furthermore,...

The First Metallo-β-Lactamase Identified in Norway Is Associated with a TniC-Like Transposon in a Pseudomonas aeruginosa Isolate of Sequence Type 233 Imported from Ghana ▿

Samuelsen, Ørjan, Buarø, Liselotte, Toleman, Mark A., Giske, Christian G., Hermansen, Nils O., Walsh, Timothy R., ...

Molecular Analysis of the Sequences Surrounding blaOXA-45 Reveals Acquisition of This Gene by Pseudomonas aeruginosa via a Novel ISCR Element, ISCR5▿

Li, Hongyang, Walsh, Timothy R., Toleman, Mark A.

The blaOXA-45 gene of Pseudomonas aeruginosa 07-406 is driven by a promoter found within a truncated ISPme1 insertion sequence. The gene is located between nonidentical repeats of a new ISCR element,...

Global Emergence of Trimethoprim/Sulfamethoxazole Resistance in Stenotrophomonas maltophilia Mediated by Acquisition of sul Genes

Toleman, Mark A., Bennett, Peter M., Bennett, David M.C., Jones, Ronald N., Walsh, Timothy R.

The first sul2 genes have been found in S. maltophilia from several different countries.

Timothy R. Walsh

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