The Experts below are selected from a list of 76449 Experts worldwide ranked by ideXlab platform
Peter W Taylor - One of the best experts on this subject based on the ideXlab platform.
-
insertion of epicatechin gallate into the cytoplasmic membrane of methicillin resistant staphylococcus aureus disrupts penicillin binding protein pbp 2a mediated beta lactam Resistance by delocalizing pbp2
Journal of Biological Chemistry, 2010Co-Authors: Patricia Bernal, Sandrine Lemaire, Mariana G Pinho, Shahriar Mobashery, Jason Hinds, Peter W TaylorAbstract:Epicatechin gallate (ECg) sensitizes methicillin-resistant Staphylococcus aureus (MRSA) to oxacillin and other Beta-Lactam agents; it also reduces the secretion of virulence-associated proteins, prevents biofilm formation, and induces gross morphological changes in MRSA cells without compromising the growth rate. MRSA is resistant to oxacillin because of the presence of penicillin-binding protein 2a (PBP2a), which allows peptidoglycan synthesis to continue after oxacillin-mediated acylation of native PBPs. We show that ECg binds predominantly to the cytoplasmic membrane (CM), initially decreasing the fluidity of the bilayer, and induces changes in gene expression indicative of an attempt to preserve and repair a compromised cell wall. On further incubation, the CM is reorganized; the amount of lysylphosphatidylglycerol is markedly reduced, with a concomitant increase in phosphatidylglycerol, and the proportion of branched chain fatty acids increases, resulting in a more fluid structure. We found no evidence that ECg modulates the enzymatic activity of PBP2a through direct binding to the protein but determined that PBP2 is delocalized from the FtsZ-anchored cell wall biosynthetic machinery at the septal division site following intercalation into the CM. We argue that many features of the ECg-induced phenotype can be explained by changes in the fluid dynamics of the CM.
-
insertion of epicatechin gallate into the cytoplasmic membrane of methicillin resistant staphylococcus aureus disrupts penicillin binding protein pbp 2a mediated beta lactam Resistance by delocalizing pbp2
Journal of Biological Chemistry, 2010Co-Authors: Patricia Bernal, Sandrine Lemaire, Mariana G Pinho, Shahriar Mobashery, Jason Hinds, Peter W TaylorAbstract:Epicatechin gallate (ECg) sensitizes methicillin-resistant Staphylococcus aureus (MRSA) to oxacillin and other β-lactam agents; it also reduces the secretion of virulence-associated proteins, prevents biofilm formation, and induces gross morphological changes in MRSA cells without compromising the growth rate. MRSA is resistant to oxacillin because of the presence of penicillin-binding protein 2a (PBP2a), which allows peptidoglycan synthesis to continue after oxacillin-mediated acylation of native PBPs. We show that ECg binds predominantly to the cytoplasmic membrane (CM), initially decreasing the fluidity of the bilayer, and induces changes in gene expression indicative of an attempt to preserve and repair a compromised cell wall. On further incubation, the CM is reorganized; the amount of lysylphosphatidylglycerol is markedly reduced, with a concomitant increase in phosphatidylglycerol, and the proportion of branched chain fatty acids increases, resulting in a more fluid structure. We found no evidence that ECg modulates the enzymatic activity of PBP2a through direct binding to the protein but determined that PBP2 is delocalized from the FtsZ-anchored cell wall biosynthetic machinery at the septal division site following intercalation into the CM. We argue that many features of the ECg-induced phenotype can be explained by changes in the fluid dynamics of the CM.
-
the β lactam Resistance modifier epicatechin gallate alters the architecture of the cell wall of staphylococcus aureus
Microbiology, 2007Co-Authors: Paul Stapleton, Saroj Shah, Yukihiko Hara, Kerstin Ehlert, Peter W TaylorAbstract:(-)-Epicatechin gallate (ECg), a component of green tea, sensitizes meticillin-resistant Staphylococcus aureus (MRSA) to Beta-Lactam antibiotics, promotes staphylococcal cell aggregation and increases cell-wall thickness. The potentiation of Beta-Lactam activity against MRSA by ECg was not due to decreased bacterial penicillin-binding protein (PBP) 2a expression or ECg binding to peptidoglycan. A 5-10 % reduction in peptidoglycan cross-linking was observed. Reduced cross-linking was insufficient to compromise the integrity of the cell wall and no evidence of PBP2a activity was detected in the muropeptide composition of ECg-grown cells. ECg increased the quantity of autolysins associated with the cell wall, even though the cells were less susceptible to Triton X-100-induced autolysis than cells grown in the absence of ECg. ECg promoted increased lysostaphin Resistance that was not due to alteration of the pentaglycine cross-bridge configuration or inhibition of lysostaphin activity. Rather, decreased lysostaphin susceptibility was associated with structural changes to wall teichoic acid (WTA), an acid-labile component of peptidoglycan. ECg also promoted lipoteichoic acid (LTA) release from the cytoplasmic membrane. It is proposed that ECg reduces Beta-Lactam Resistance in MRSA either by binding to PBPs at sites distinct from the penicillin-binding site or by intercalation into the cytoplasmic membrane, displacing LTA from the phospholipid palisade. Thus, ECg-mediated alterations to the physical nature of the bilayer will elicit structural changes to WTA that result in modulation of the cell-surface properties necessary to maintain the Beta-Lactam-resistant phenotype.
-
modulation of β lactam Resistance in staphylococcus aureus by catechins and gallates
International Journal of Antimicrobial Agents, 2004Co-Authors: Paul D Stapleton, Saroj Shah, James C Anderson, Yukihiko Hara, J M T Hamiltonmiller, Peter W TaylorAbstract:Aqueous extracts of Japanese green tea (Camellia sinensis) are able to reverse Beta-Lactam Resistance in methicillin-resistant Staphylococcus aureus (MRSA). We have attributed the capacity to reverse oxacillin Resistance in the homogeneous PBP2a producer BB568 and in EMRSA-16 to (-)-epicatechin gallate (ECG) and (-)-catechin gallate (CG). Minimum inhibitory concentration (MIC) values for oxacillin were reduced from 256 and 512 to 1-4 mg/l, respectively, in the presence of these polyphenols. In addition, (-)-epigallocatechin gallate (EGCG) had a moderate capacity to modulate oxacillin activity against S. aureus BB568, but none against EMRSA-16. ECG, CG and EGCG increased the sensitivity of EMRSA-15 to oxacillin. The gallate moiety was essential for the oxacillin-modulating activity of ECG, as both (-)-epicatechin and (-)-epicatechin-3-cyclohexylcarboxylate were unable to reverse Resistance to oxacillin. Gallic acid and three alkyl gallates (methyl gallate, propyl gallate, and octyl gallate) did not modulate Beta-Lactam Resistance in MRSA. Octyl gallate exhibited direct antibacterial activity against S. aureus BB568 (16 mg/l). Modulation of Beta-Lactam Resistance by ECG significantly enhanced the activities of flucloxacillin and the carbapenem antibiotics imipenem and meropenem against 40 MRSA isolates, with MIC(90) values for the antibiotics reduced to the susceptibility breakpoint or below. Consequently, EGCG, CG and, particularly, ECG warrant further investigation as agents to combat Beta-Lactam Resistance in S. aureus.
Ralf Ehricht - One of the best experts on this subject based on the ideXlab platform.
-
Detection of mecC-Positive Staphylococcus aureus (CC130-MRSA-XI) in Diseased European Hedgehogs (Erinaceus europaeus) in Sweden
2016Co-Authors: Stefan Monecke, Dolores Gavier-widen, Lena Rangstrup-christensen, Ros Lazaris, David C. Coleman, Anna C. Shore, Ralf EhrichtAbstract:Recently, a novel mec gene conferring Beta-Lactam Resistance in Staphylococcus aureus has been discovered. This gene, mecC, is situated on a SCCmec XI element that has to date been identified in clonal complexes 49, 130, 425, 599 and 1943. Some of the currently known isolates have been identified from animals. This, and observations of mecA alleles that do not confer Beta-Lactam Resistance, indicate that mec genes might have a reservoir in Staphylococcus species from animals. Thus it is important also to screen wildlife isolates for mec genes. Here, we describe mecC-positive Staphylococcus aureus (ST130-MRSA-XI) and the lesions related to the infection in two diseased free-ranging European hedgehogs (Erinaceus europaeus). One was found dead in 2003 in central Sweden, and suffered from S. aureus septicaemia. The other one, found on the island of Gotland in the Baltic Sea in 2011, showed a severe dermatitis and was euthanised. ST130-MRSA-XI isolates were isolated from lesions from both hedgehogs and were essentially identical to previously described isolates from humans. Both isolates carried the complete SCCmec XI element. They lacked the lukF-PV/lukS-PV and lukM/lukF-P83 genes, but harboured a gene for an exfoliative toxin homologue previously described from Staphylococcus hyicus, Staphylococcus pseudintermedius and other S. aureus of the CC130 lineage. To the best of our knowledge, these are the first reported cases of CC130-MRSA-X
-
detection of mecc positive staphylococcus aureus cc130 mrsa xi in diseased european hedgehogs erinaceus europaeus in sweden
PLOS ONE, 2013Co-Authors: Stefan Monecke, David C. Coleman, Anna C. Shore, Dolores Gavierwiden, Roland Mattsson, Lena Rangstrupchristensen, Alexandros Lazaris, Ralf EhrichtAbstract:Recently, a novel mec gene conferring Beta-Lactam Resistance in Staphylococcus aureus has been discovered. This gene, mecC, is situated on a SCCmec XI element that has to date been identified in clonal complexes 49, 130, 425, 599 and 1943. Some of the currently known isolates have been identified from animals. This, and observations of mecA alleles that do not confer Beta-Lactam Resistance, indicate that mec genes might have a reservoir in Staphylococcus species from animals. Thus it is important also to screen wildlife isolates for mec genes. Here, we describe mecC-positive Staphylococcus aureus (ST130-MRSA-XI) and the lesions related to the infection in two diseased free-ranging European hedgehogs (Erinaceus europaeus). One was found dead in 2003 in central Sweden, and suffered from S. aureus septicaemia. The other one, found on the island of Gotland in the Baltic Sea in 2011, showed a severe dermatitis and was euthanised. ST130-MRSA-XI isolates were isolated from lesions from both hedgehogs and were essentially identical to previously described isolates from humans. Both isolates carried the complete SCCmec XI element. They lacked the lukF-PV/lukS-PV and lukM/lukF-P83 genes, but harboured a gene for an exfoliative toxin homologue previously described from Staphylococcus hyicus, Staphylococcus pseudintermedius and other S. aureus of the CC130 lineage. To the best of our knowledge, these are the first reported cases of CC130-MRSA-XI in hedgehogs. Given that one of the samples was taken as early as 2003, this was the earliest detection of this strain and of mecC in Sweden. This and several other recent observations suggest that CC130 might be a zoonotic lineage of S. aureus and that SCCmec XI/mecC may have originated from animal pathogens.
Laurent Gutmann - One of the best experts on this subject based on the ideXlab platform.
-
The Beta-Lactam-sensitive D,D-carboxypeptidase activity of Pbp4 controls the L,D and D,D transpeptidation pathways in Corynebacterium jeikeium.
Molecular microbiology, 2009Co-Authors: Marie Lavollay, Laurent Gutmann, Michel Arthur, Martine Fourgeaud, Lionel Dubost, Arul Marie, Philippe Riegel, Jeanluc MainardiAbstract:Corynebacterium jeikeium is an emerging nosocomial pathogen responsible for vascular catheters infections, prosthetic endocarditis and septicemia. The treatment of C. jeikeium infections is complicated by the multiResistance of clinical isolates to antibiotics, in particular to Beta-Lactams, the most broadly used class of antibiotics. To gain insight into the mechanism of Beta-Lactam Resistance, we have determined the structure of the peptidoglycan and shown that C. jeikeium has the dual capacity to catalyse formation of cross-links generated by transpeptidases of the d,d and l,d specificities. Two ampicillin-insensitive cross-linking enzymes were identified, Ldt(Cjk1), a member of the active site cysteine l,d-transpeptidase family, and Pbp2c, a low-affinity class B penicillin-binding protein (PBP). In the absence of Beta-Lactam, the PBPs and the l,d-transpeptidase contributed to the formation of 62% and 38% of the cross-links respectively. Although Ldt(Cjk1) and Pbp2C were not inhibited by ampicillin, the participation of the l,d-transpeptidase to peptidoglycan cross-linking decreased in the presence of the drug. The specificity of Ldt(Cjk1) for acyl donors containing a tetrapeptide stem accounts for this effect of ampicillin since the essential substrate of Ldt(Cjk1) was produced by an ampicillin-sensitive d,d-carboxypeptidase (Pbp4(Cjk)). Acquisition and mutational alterations of pbp2C accounted for high-level Beta-Lactam Resistance in C. jeikeium.
-
penicillin binding protein 5 sequence alterations in clinical isolates of enterococcus faecium with different levels of β lactam Resistance
The Journal of Infectious Diseases, 1998Co-Authors: Tania Rybkine, Wladimir Sougakoff, Jeanluc Mainardi, E Collatz, Laurent GutmannAbstract:The low-affinity penicillin-binding protein (PBP) 5 is the main Beta-Lactam target and is responsible for Resistance to this class of antibiotics in Enterococcus faecium. The PBP 5 variants of 15 clinical isolates (including 8 resistant to vancomycin) with different levels of Beta-Lactam Resistance were analyzed. Most of the highly Beta-Lactam-resistant isolates produced small quantities of PBP 5 of low affinity. This was associated with particular amino acid substitutions: an Ala or Ile for Thr-499, a Glu for Val-629, and a Pro for Ser-667. A change of Met-485 to Thr or Ala (adjacent to the conserved SDN box) was observed in isolates with MICs of ampicillin of 64 or 128 microg/mL, respectively. In the 2 most resistant isolates, with MICs of ampicillin of 256 microg/mL, an additional Ser was present just after Ser-466. Thus, particular point mutations in PBP 5 and combinations thereof may lead to high-level Beta-Lactam Resistance in E. faecium.
-
acquisition of five high mr penicillin binding protein variants during transfer of high level beta lactam Resistance from streptococcus mitis to streptococcus pneumoniae
Journal of Bacteriology, 1998Co-Authors: Regine Hakenbeck, Andrea Konig, Izabella Kern, Mark Van Der Linden, Wolfgang Keck, Danielle Billotklein, Raymond Legrand, Bernard Schoot, Laurent GutmannAbstract:Penicillin-resistant isolates of Streptococcus pneumoniae generally contain mosaic genes encoding the low-affinity penicillin-binding proteins (PBPs) PBP2x, PBP2b, and PBP1a. We now present evidence that PBP2a and PBP1b also appear to be low-affinity variants and are encoded by distinct alleles in Beta-Lactam-resistant transformants of S. pneumoniae obtained with chromosomal donor DNA from a Streptococcus mitis isolate. Different lineages of Beta-Lactam-resistant pneumococcal transformants were analyzed, and transformants with low-affinity variants of all high-molecular-mass PBPs, PBP2x, -2a, -2b, -1a, and -1b, were isolated. The MICs of benzyl-penicillin, oxacillin, and cefotaxime for these transformants were up to 40, 100, and 50 microg/ml, respectively, close to the MICs for the S. mitis donor strain. Recruitment of low-affinity PBPs was accompanied by a decrease in cross-linked muropeptides as revealed by high-performance liquid chromatography of muramidase-digested cell walls, but no qualitative changes in muropeptide chemistry were detected. The growth rates of all transformants were identical to that of the parental S. pneumoniae strain. The results stress the potential for the acquisition by S. pneumoniae of high-level Beta-Lactam Resistance by interspecies gene transfer.
-
acquisition of five high mr penicillin binding protein variants during transfer of high level beta lactam Resistance from streptococcus mitis to streptococcus pneumoniae
Journal of Bacteriology, 1998Co-Authors: Regine Hakenbeck, Andrea Konig, Izabella Kern, Mark Van Der Linden, Wolfgang Keck, Danielle Billotklein, Raymond Legrand, Bernard Schoot, Laurent GutmannAbstract:Penicillin-resistant isolates of Streptococcus pneumoniae generally contain mosaic genes encoding the lowaffinity penicillin-binding proteins (PBPs) PBP2x, PBP2b, and PBP1a. We now present evidence that PBP2a and PBP1b also appear to be low-affinity variants and are encoded by distinct alleles in b-lactam-resistant transformants of S. pneumoniae obtained with chromosomal donor DNA from a Streptococcus mitis isolate. Different lineages of b-lactam-resistant pneumococcal transformants were analyzed, and transformants with low-affinity variants of all high-molecular-mass PBPs, PBP2x, -2a, -2b, -1a, and -1b, were isolated. The MICs of benzylpenicillin, oxacillin, and cefotaxime for these transformants were up to 40, 100, and 50 mg/ml, respectively, close to the MICs for the S. mitis donor strain. Recruitment of low-affinity PBPs was accompanied by a decrease in cross-linked muropeptides as revealed by high-performance liquid chromatography of muramidase-digested cell walls, but no qualitative changes in muropeptide chemistry were detected. The growth rates of all transformants were identical to that of the parental S. pneumoniae strain. The results stress the potential for the acquisition by S. pneumoniae of high-level b-lactam Resistance by interspecies gene transfer.
Dolores Gavierwiden - One of the best experts on this subject based on the ideXlab platform.
-
detection of mecc positive staphylococcus aureus cc130 mrsa xi in diseased european hedgehogs erinaceus europaeus in sweden
PLOS ONE, 2013Co-Authors: Stefan Monecke, David C. Coleman, Anna C. Shore, Dolores Gavierwiden, Roland Mattsson, Lena Rangstrupchristensen, Alexandros Lazaris, Ralf EhrichtAbstract:Recently, a novel mec gene conferring Beta-Lactam Resistance in Staphylococcus aureus has been discovered. This gene, mecC, is situated on a SCCmec XI element that has to date been identified in clonal complexes 49, 130, 425, 599 and 1943. Some of the currently known isolates have been identified from animals. This, and observations of mecA alleles that do not confer Beta-Lactam Resistance, indicate that mec genes might have a reservoir in Staphylococcus species from animals. Thus it is important also to screen wildlife isolates for mec genes. Here, we describe mecC-positive Staphylococcus aureus (ST130-MRSA-XI) and the lesions related to the infection in two diseased free-ranging European hedgehogs (Erinaceus europaeus). One was found dead in 2003 in central Sweden, and suffered from S. aureus septicaemia. The other one, found on the island of Gotland in the Baltic Sea in 2011, showed a severe dermatitis and was euthanised. ST130-MRSA-XI isolates were isolated from lesions from both hedgehogs and were essentially identical to previously described isolates from humans. Both isolates carried the complete SCCmec XI element. They lacked the lukF-PV/lukS-PV and lukM/lukF-P83 genes, but harboured a gene for an exfoliative toxin homologue previously described from Staphylococcus hyicus, Staphylococcus pseudintermedius and other S. aureus of the CC130 lineage. To the best of our knowledge, these are the first reported cases of CC130-MRSA-XI in hedgehogs. Given that one of the samples was taken as early as 2003, this was the earliest detection of this strain and of mecC in Sweden. This and several other recent observations suggest that CC130 might be a zoonotic lineage of S. aureus and that SCCmec XI/mecC may have originated from animal pathogens.
Alexander Tomasz - One of the best experts on this subject based on the ideXlab platform.
-
role of the stringent stress response in the antibiotic Resistance phenotype of methicillin resistant staphylococcus aureus
Antimicrobial Agents and Chemotherapy, 2016Co-Authors: Sandra Aedo, Alexander TomaszAbstract:Resistance to Beta-Lactam antibiotics in methicillin-resistantStaphylococcus aureus(MRSA) requires the presence of an acquired genetic determinant,mecAormecC, which encode penicillin-binding protein PBP2A or PBP2A', respectively. Although all MRSA strains share a mechanism of Resistance, the phenotypic expression of Beta-Lactam Resistance shows considerable strain-to-strain variation. The stringent stress response, a stress response that results from nutrient limitation, was shown to play a key role in determining the Resistance level of an MRSA strain. In the present study, we validated the impact of the stringent stress response on transcription and translation ofmecAin the MRSA clinical isolate strain N315, which also carries known regulatory genes (mecI/mecR1/mecR2andblaI/blaR1) formecAtranscription. We showed that the impact of the stringent stress response on the Resistance level may be restricted to Beta-Lactam Resistance based on a "foreign" determinant such asmecA, as opposed to Resistance based on mutations in the nativeS. aureusdeterminantpbpB(encoding PBP2). Our observations demonstrate that high-level Resistance mediated by the stringent stress response follows the current model of Beta-Lactam Resistance in which the native PBP2 protein is also essential for expression of the Resistance phenotype. We also show that theStaphylococcus sciuri pbpDgene (also calledmecAI), the putative evolutionary precursor ofmecA, confers oxacillin Resistance in anS. aureusstrain, generating a heterogeneous phenotype that can be converted to high and homogenous Resistance by induction of the stringent stress response in the bacteria.
-
The mechanism of heterogeneous Beta-Lactam Resistance in MRSA: Key role of the stringent stress response
PLoS ONE, 2013Co-Authors: Choonkeun Kim, Michael Mwangi, Marilyn Chung, Catarina Milheirco, Herminia De Lencastre, Alexander TomaszAbstract:All methicillin resistant S. aureus (MRSA) strains carry an acquired genetic determinant - mecA or mecC - which encode for a low affinity penicillin binding protein -PBP2A or PBP2A' - that can continue the catalysis of peptidoglycan transpeptidation in the presence of high concentrations of Beta-Lactam antibiotics which would inhibit the native PBPs normally involved with the synthesis of staphylococcal cell wall peptidoglycan. In contrast to this common genetic and biochemical mechanism carried by all MRSA strains, the level of Beta-Lactam antibiotic Resistance shows a very wide strain to strain variation, the mechanism of which has remained poorly understood. The overwhelming majority of MRSA strains produce a unique - heterogeneous - phenotype in which the great majority of the bacteria exhibit very poor Resistance often close to the MIC value of susceptible S. aureus strains. However, cultures of such heterogeneously resistant MRSA strains also contain subpopulations of bacteria with extremely high Beta-Lactam MIC values and the Resistance level and frequency of the highly resistant cells in such strain is a characteristic of the particular MRSA clone. In the study described in this communication, we used a variety of experimental models to understand the mechanism of heterogeneous Beta-Lactam Resistance. Methicillin-susceptible S. aureus (MSSA) that received the mecA determinant in the laboratory either on a plasmid or in the form of a chromosomal SCCmec cassette, generated heterogeneously resistant cultures and the highly resistant subpopulations that emerged in these models had increased levels of PBP2A and were composed of bacteria in which the stringent stress response was induced. Each of the major heterogeneously resistant clones of MRSA clinical isolates could be converted to express high level and homogeneous Resistance if the growth medium contained an inducer of the stringent stress response.
-
role of penicillin binding protein 2 pbp2 in the antibiotic susceptibility and cell wall cross linking of staphylococcus aureus evidence for the cooperative functioning of pbp2 pbp4 and pbp2a
Journal of Bacteriology, 2005Co-Authors: Tomasz A łeski, Alexander TomaszAbstract:Ceftizoxime, a Beta-Lactam antibiotic with high selective affinity for penicillin-binding protein 2 (PBP2) of Staphylococcus aureus, was used to select a spontaneous resistant mutant of S. aureus strain 27s. The stable resistant mutant ZOX3 had an increased ceftizoxime MIC and a decreased affinity of its PBP2 for ceftizoxime and produced peptidoglycan in which the proportion of highly cross-linked muropeptides was reduced. The pbpB gene of ZOX3 carried a single C-to-T nucleotide substitution at nucleotide 1373, causing replacement of a proline with a leucine at amino acid residue 458 of the transpeptidase domain of the protein, close to the SFN conserved motif. Experimental proof that this point mutation was responsible for the drug-resistant phenotype, and also for the decreased PBP2 affinity and reduced cell wall cross-linking, was provided by allelic replacement experiments and site-directed mutagenesis. Disruption of pbpD, the structural gene of PBP4, in either the parental strain or the mutant caused a large decrease in the highly cross-linked muropeptide components of the cell wall and in the mutant caused a massive accumulation of muropeptide monomers as well. Disruption of pbpD also caused increased sensitivity to ceftizoxime in both the parental cells and the ZOX3 mutant, while introduction of the plasmid-borne mecA gene, the genetic determinant of the Beta-Lactam Resistance protein PBP2A, had the opposite effects. The findings provide evidence for the cooperative functioning of two native S. aureus transpeptidases (PBP2 and PBP4) and an acquired transpeptidase (PBP2A) in staphylococcal cell wall biosynthesis and susceptibility to antimicrobial agents.