51
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Fishovitz J, Taghizadeh N, Fisher JF, Chang M, Mobashery S. The Tipper-Strominger Hypothesis and Triggering of Allostery in Penicillin-Binding Protein 2a of Methicillin-Resistant Staphylococcus aureus (MRSA). J Am Chem Soc 2015; 137:6500-5. [PMID: 25964995 DOI: 10.1021/jacs.5b01374] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The transpeptidases involved in the synthesis of the bacterial cell wall (also known as penicillin-binding proteins, PBPs) have evolved to bind the acyl-D-Ala-D-Ala segment of the stem peptide of the nascent peptidoglycan for the physiologically important cross-linking of the cell wall. The Tipper-Strominger hypothesis stipulates that β-lactam antibiotics mimic the acyl-D-Ala-D-Ala moiety of the stem and, thus, are recognized by the PBPs with bactericidal consequences. We document that this mimicry exists also at the allosteric site of PBP2a of methicillin-resistant Staphylococcus aureus (MRSA). Interactions of different classes of β-lactam antibiotics, as mimics of the acyl-D-Ala-D-Ala moiety at the allosteric site, lead to a conformational change, across a distance of 60 Å to the active site. We directly visualize this change using an environmentally sensitive fluorescent probe affixed to the protein loops that frame the active site. This conformational mobility, documented in real time, allows antibiotic access to the active site of PBP2a. Furthermore, we document that this allosteric trigger enables synergy between two different β-lactam antibiotics, wherein occupancy at the allosteric site by one facilitates occupancy by a second at the transpeptidase catalytic site, thus lowering the minimal-inhibitory concentration. This synergy has important implications for the mitigation of facile emergence of resistance to these antibiotics by MRSA.
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Affiliation(s)
- Jennifer Fishovitz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Negin Taghizadeh
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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52
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Kelley WL, Jousselin A, Barras C, Lelong E, Renzoni A. Missense mutations in PBP2A Affecting ceftaroline susceptibility detected in epidemic hospital-acquired methicillin-resistant Staphylococcus aureus clonotypes ST228 and ST247 in Western Switzerland archived since 1998. Antimicrob Agents Chemother 2015; 59:1922-30. [PMID: 25583724 PMCID: PMC4356817 DOI: 10.1128/aac.04068-14] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 01/07/2015] [Indexed: 12/28/2022] Open
Abstract
The development and maintenance of an arsenal of antibiotics is a major health care challenge. Ceftaroline is a new cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA); however, no reports concerning MRSA ceftaroline susceptibility have been reported in Switzerland. We tested the in vitro activity of ceftaroline against an archived set of 60 MRSA strains from the University Hospital of Geneva collected from 1994 to 2003. Our results surprisingly revealed ceftaroline-resistant strains (MIC, >1 μg/ml in 40/60 strains; EUCAST breakpoints, susceptible [S], ≤1 μg/ml; resistant [R], >1 μg/ml) were present from 1998 to 2003. The detected resistant strains predominantly belonged to sequence type 228 (ST228) (South German clonotype) but also to ST247 (Iberian clonotype). A sequence analysis of these strains revealed missense mutations in the penicillin-binding protein 2A (PBP2A) allosteric domain (N146K or E239K and N146K-E150K-G246E). The majority of our ST228 PBP2A mutations (N146K or E150K) were distinct from ST228 PBP2A allosteric domain mutations (primarily E239K) recently described for MRSA strains collected in Thailand and Spain during the 2010 Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) global surveillance program. We also found that similar allosteric domain PBP2A mutations (N146K) correlated with ceftaroline resistance in an independent external ST228 MRSA set obtained from the nearby University Hospital of Lausanne, Lausanne, Switzerland, collected from 2003 to 2008. Thus, ceftaroline resistance was observed in our archived strains (including two examples of an MIC of 4 µg/ml for the Iberian ST247 clonotype with the triple mutation N146K/E150K/G246E), at least as far back as 1998, considerably predating the commercial introduction of ceftaroline. Our results reinforce the notion that unknown parameters can potentially exert selective pressure on PBP2A that can subsequently modulate ceftaroline resistance.
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Affiliation(s)
- William L Kelley
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, Geneva, Switzerland
| | - Ambre Jousselin
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, Geneva, Switzerland
| | - Christine Barras
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, Geneva, Switzerland
| | - Emmanuelle Lelong
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, Geneva, Switzerland
| | - Adriana Renzoni
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, Geneva, Switzerland
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53
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Staude MW, Frederick TE, Natarajan SV, Wilson BD, Tanner CE, Ruggiero ST, Mobashery S, Peng JW. Investigation of signal transduction routes within the sensor/transducer protein BlaR1 of Staphylococcus aureus. Biochemistry 2015; 54:1600-10. [PMID: 25658195 DOI: 10.1021/bi501463k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transmembrane antibiotic sensor/signal transducer protein BlaR1 is part of a cohort of proteins that confer β-lactam antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) [Fisher, J. F., Meroueh, S. O., and Mobashery, S. (2005) Chem. Rev. 105, 395-424; Llarrull, L. I., Fisher, J. F., and Mobashery, S. (2009) Antimicrob. Agents Chemother. 53, 4051-4063; Llarrull, L. I., Toth, M., Champion, M. M., and Mobashery, S. (2011) J. Biol. Chem. 286, 38148-38158]. Specifically, BlaR1 regulates the inducible expression of β-lactamases that hydrolytically destroy β-lactam antibiotics. The resistance phenotype starts with β-lactam antibiotic acylation of the BlaR1 extracellular domain (BlaRS). The acylation activates the cytoplasmic protease domain through an obscure signal transduction mechanism. Here, we compare protein dynamics of apo versus antibiotic-acylated BlaRS using nuclear magnetic resonance. Our analyses reveal inter-residue interactions that relay acylation-induced perturbations within the antibiotic-binding site to the transmembrane helix regions near the membrane surface. These are the first insights into the process of signal transduction by BlaR1.
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Affiliation(s)
- Michael W Staude
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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54
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Liu M, Lu J, Müller P, Turnbull L, Burke CM, Schlothauer RC, Carter DA, Whitchurch CB, Harry EJ. Antibiotic-specific differences in the response of Staphylococcus aureus to treatment with antimicrobials combined with manuka honey. Front Microbiol 2015; 5:779. [PMID: 25674077 PMCID: PMC4307217 DOI: 10.3389/fmicb.2014.00779] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/18/2014] [Indexed: 01/02/2023] Open
Abstract
Skin infections caused by antibiotic resistant Staphylococcus aureus are a significant health problem worldwide; often associated with high treatment cost and mortality rate. Complex natural products like New Zealand (NZ) manuka honey have been revisited and studied extensively as an alternative to antibiotics due to their potent broad-spectrum antimicrobial activity, and the inability to isolate honey-resistant S. aureus. Previous studies showing synergistic effects between manuka-type honeys and antibiotics have been demonstrated against the growth of one methicillin-resistant S. aureus (MRSA) strain. We have previously demonstrated strong synergistic activity between NZ manuka-type honey and rifampicin against growth and biofilm formation of multiple S. arueus strains. Here, we have expanded our investigation using multiple S. aureus strains and four different antibiotics commonly used to treat S. aureus-related skin infections: rifampicin, oxacillin, gentamicin, and clindamycin. Using checkerboard microdilution and agar diffusion assays with S. aureus strains including clinical isolates and MRSA we demonstrate that manuka-type honey combined with these four antibiotics frequently produces a synergistic effect. In some cases when synergism was not observed, there was a significant enhancement in antibiotic susceptibility. Some strains that were highly resistant to an antibiotic when present alone become sensitive to clinically achievable concentrations when combined with honey. However, not all of the S. aureus strains tested responded in the same way to these combinational treatments. Our findings support the use of NZ manuka-type honeys in clinical treatment against S. aureus-related infections and extend their potential use as an antibiotic adjuvant in combinational therapy. Our data also suggest that manuka-type honeys may not work as antibiotic adjuvants for all strains of S. aureus, and this may help determine the mechanistic processes behind honey synergy.
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Affiliation(s)
- Michael Liu
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
| | - Jing Lu
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
| | - Patrick Müller
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
| | - Lynne Turnbull
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
| | - Catherine M Burke
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
| | | | - Dee A Carter
- School of Molecular Bioscience, University of Sydney, Sydney, NSW Australia
| | | | - Elizabeth J Harry
- The ithree institute, University of Technology, Sydney, Sydney, NSW Australia
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55
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Suleman N, Kalhapure RS, Mocktar C, Rambharose S, Singh M, Govender T. Silver salts of carboxylic acid terminated generation 1 poly (propyl ether imine) (PETIM) dendron and dendrimers as antimicrobial agents against S. aureus and MRSA. RSC Adv 2015. [DOI: 10.1039/c5ra03179f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this study the newly synthesised PETIM silver salts displayed a low toxicity level and showed significant antimicrobial activity against both sensitive (S. aureus) and resistant (MRSA) bacterial strains.
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Affiliation(s)
- Nadia Suleman
- Discipline of Pharmaceutical Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
| | - Rahul S. Kalhapure
- Discipline of Pharmaceutical Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
| | - Chunderika Mocktar
- Discipline of Pharmaceutical Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
| | - Sanjeev Rambharose
- Discipline of Pharmaceutical Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
| | - Moganavelli Singh
- Discipline of Biochemistry
- School of Life Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
| | - Thirumala Govender
- Discipline of Pharmaceutical Sciences
- University of KwaZulu-Natal
- Durban 4000
- South Africa
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56
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Recovery of plasmid pEMB1, whose toxin-antitoxin system stabilizes an ampicillin resistance-conferring β-lactamase gene in Escherichia coli, from natural environments. Appl Environ Microbiol 2014; 81:40-7. [PMID: 25304509 DOI: 10.1128/aem.02691-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Non-culture-based procedures were used to investigate plasmids showing ampicillin resistance properties in two different environments: remote mountain soil (Mt. Jeombong) and sludge (Tancheon wastewater treatment plant). Total DNA extracted from the environmental samples was directly transformed into Escherichia coli TOP10, and a single and three different plasmids were obtained from the mountain soil and sludge samples, respectively. Interestingly, the restriction fragment length polymorphism pattern of the plasmid from the mountain soil sample, designated pEMB1, was identical to the pattern of one of the three plasmids from the sludge sample. Complete DNA sequencing of plasmid pEMB1 (8,744 bp) showed the presence of six open reading frames, including a β-lactamase gene. Using BLASTX, the orf5 and orf6 genes were suggested to encode a CopG family transcriptional regulator and a plasmid stabilization system, respectively. Functional characterization of these genes using a knockout orf5 plasmid (pEMB1ΔparD) and the cloning and expression of orf6 (pET21bparE) indicated that these genes were antitoxin (parD) and toxin (parE) genes. Plasmid stability tests using pEMB1 and pEMB1ΔparDE in E. coli revealed that the orf5 and orf6 genes enhanced plasmid maintenance in the absence of ampicillin. Using a PCR-based survey, pEMB1-like plasmids were additionally detected in samples from other human-impacted sites (sludge samples) and two other remote mountain soil samples, suggesting that plasmids harboring a β-lactamase gene with a ParD-ParE toxin-antitoxin system occurs broadly in the environment. This study extends knowledge about the dissemination and persistence of antibiotic resistance genes in naturally occurring microbial populations.
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57
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Riccobene T, Jakate A, Rank D. A series of pharmacokinetic studies of ceftaroline fosamil in select populations: normal subjects, healthy elderly subjects, and subjects with renal impairment or end-stage renal disease requiring hemodialysis. J Clin Pharmacol 2014; 54:742-52. [PMID: 24431097 DOI: 10.1002/jcph.265] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 01/09/2014] [Indexed: 12/16/2023]
Abstract
Ceftaroline fosamil is a parenteral cephalosporin indicated for the treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. Ceftaroline, the active component of ceftaroline fosamil, exhibits broad-spectrum bactericidal activity against gram-positive organisms, including methicillin-resistant Staphylococcus aureus and Streptococcus pneumoniae, as well as common gram-negative pathogens. The objective of the studies presented herein was to establish the pharmacokinetic profile of ceftaroline in healthy subjects and special populations of interest, such as elderly subjects, subjects with renal impairment, or subjects with end-stage renal disease on intermittent hemodialysis. The mean half-life of ceftaroline in healthy subjects was approximately 2.6 hours, and urinary excretion was the primary route of elimination. Ceftaroline Cmax and AUC values increased in proportion to dose increases within the range of 50-1000 mg, demonstrating an approximately linear pharmacokinetic profile following intravenous infusion. The pharmacokinetic parameters of ceftaroline were modestly altered in elderly subjects compared with younger adults, which was attributed to decreased renal function in elderly subjects. Ceftaroline pharmacokinetic parameters varied with different degrees of renal impairment, resulting in recommended dosage adjustments for patients with moderate to severe impairment. Ceftaroline fosamil was generally well tolerated regardless of age or severity of renal impairment.
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58
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Borbón-Esquer EM, Villaseñor-Sierra A, Martínez-López E, Jáuregui-Lomeli JJ, Villaseñor-Martínez R, Ruiz-Briseño MDR. SCCmec types and pvl gene in methicillin-resistant Staphylococcus aureus strains from children hospitalized in a tertiary care hospital in Mexico. ACTA ACUST UNITED AC 2014; 46:523-7. [PMID: 24832853 DOI: 10.3109/00365548.2014.912349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The aim of this study was to determine the prevalence, SCCmec types, presence of the Panton-Valentine leukocidin (PVL) gene, and susceptibility to antibiotics of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from hospitalized children. METHODS From August 2009 to September 2011, 291 S. aureus strains were isolated from normally sterile body sites, of which 190 (65%) were MRSA. One hundred and two of the MRSA strains were genetically evaluated. SCCmec genotypes were identified by M-PCR and the PVL gene (pvl) by end-point PCR. Resistance to erythromycin, rifampicin, clindamycin, and trimethoprim-sulfamethoxazole (SXT) was assessed by Kirby-Bauer disk diffusion method in accordance with the Clinical and Laboratory Standards Institute guidelines of 2012. RESULTS Of the 102 strains evaluated, 97 (95%) were SCCmec type II, 5 (5%) were SCCmec type IVa, and all (100%) were pvl-negative. Resistance to erythromycin, clindamycin, rifampicin, and SXT was 97%, 95%, 0%, and 0%, respectively. CONCLUSIONS The prevalence of hospital-acquired MRSA was high. SCCmec type II was predominant and the pvl gene appeared not to play any role in the virulence of the MRSA strains from hospitalized children.
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59
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A rifamycin inactivating phosphotransferase family shared by environmental and pathogenic bacteria. Proc Natl Acad Sci U S A 2014; 111:7102-7. [PMID: 24778229 DOI: 10.1073/pnas.1402358111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many environmental bacteria are multidrug-resistant and represent a reservoir of ancient antibiotic resistance determinants, which have been linked to genes found in pathogens. Exploring the environmental antibiotic resistome, therefore, reveals the diversity and evolution of antibiotic resistance and also provides insight into the vulnerability of clinically used antibiotics. In this study, we describe the identification of a highly conserved regulatory motif, the rifampin (RIF) -associated element (RAE), which is found upstream of genes encoding RIF-inactivating enzymes from a diverse collection of actinomycetes. Using gene expression assays, we confirmed that the RAE is involved in RIF-responsive regulation. By using the RAE as a probe for new RIF-associated genes in several actinomycete genomes, we identified a heretofore unknown RIF resistance gene, RIF phosphotransferase (rph). The RPH enzyme is a RIF-inactivating phosphotransferase and represents a new protein family in antibiotic resistance. RPH orthologs are widespread and found in RIF-sensitive bacteria, including Bacillus cereus and the pathogen Listeria monocytogenes. Heterologous expression and in vitro enzyme assays with purified RPHs from diverse bacterial genera show that these enzymes are capable of conferring high-level resistance to a variety of clinically used rifamycin antibiotics. This work identifies a new antibiotic resistance protein family and reinforces the fact that the study of resistance in environmental organisms can serve to identify resistance elements with relevance to pathogens.
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60
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Blázquez B, Llarrull LI, Luque-Ortega JR, Alfonso C, Boggess B, Mobashery S. Regulation of the expression of the β-lactam antibiotic-resistance determinants in methicillin-resistant Staphylococcus aureus (MRSA). Biochemistry 2014; 53:1548-50. [PMID: 24564530 PMCID: PMC3971960 DOI: 10.1021/bi500074w] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
![]()
β-Lactam
antibiotics have faced obsolescence with the emergence
of methicillin-resistant Staphylococcus aureus (MRSA).
A complex set of events ensues upon exposure of MRSA to these antibiotics,
which culminates in proteolysis of BlaI or MecI, two gene repressors,
and results in the induction of resistance. We report studies on the
mechanism of binding of these gene repressors to the operator regions
by fluorescence anisotropy. Within the range of in vivo concentrations for BlaI and MecI, these proteins interact with their
regulatory elements in a reversible manner, as both a monomer and
a dimer.
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Affiliation(s)
- Blas Blázquez
- Department Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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61
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O'Daniel PI, Peng Z, Pi H, Testero SA, Ding D, Spink E, Leemans E, Boudreau MA, Yamaguchi T, Schroeder VA, Wolter WR, Llarrull LI, Song W, Lastochkin E, Kumarasiri M, Antunes NT, Espahbodi M, Lichtenwalter K, Suckow MA, Vakulenko S, Mobashery S, Chang M. Discovery of a new class of non-β-lactam inhibitors of penicillin-binding proteins with Gram-positive antibacterial activity. J Am Chem Soc 2014; 136:3664-72. [PMID: 24517363 PMCID: PMC3985699 DOI: 10.1021/ja500053x] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Infections
caused by hard-to-treat methicillin-resistant Staphylococcus
aureus (MRSA) are a serious global
public-health concern, as MRSA has become broadly resistant to many
classes of antibiotics. We disclose herein the discovery of a new
class of non-β-lactam antibiotics, the oxadiazoles, which inhibit
penicillin-binding protein 2a (PBP2a) of MRSA. The oxadiazoles show
bactericidal activity against vancomycin- and linezolid-resistant
MRSA and other Gram-positive bacterial strains, in vivo efficacy in a mouse model of infection, and have 100% oral bioavailability.
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Affiliation(s)
- Peter I O'Daniel
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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62
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Frederick TE, Wilson BD, Cha J, Mobashery S, Peng JW. Revealing cell-surface intramolecular interactions in the BlaR1 protein of methicillin-resistant Staphylococcus aureus by NMR spectroscopy. Biochemistry 2013; 53:10-2. [PMID: 24359467 DOI: 10.1021/bi401552j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In methicillin-resistant Staphylococcus aureus, β-lactam antibiotic resistance is mediated by the transmembrane protein BlaR1. The antibiotic sensor domain BlaR(S) and the L2 loop of BlaR1 are on the membrane surface. We used NMR to investigate interactions between BlaR(S) and a water-soluble peptide from L2. This peptide binds BlaR(S) proximal to the antibiotic acylation site as an amphipathic helix. Acylation of BlaR(S) by penicillin G does not disrupt binding. These results suggest a signal transduction mechanism whereby the L2 helix, partially embedded in the membrane, propagates conformational changes caused by BlaR(S) acylation through the membrane via transmembrane segments, leading to antibiotic resistance.
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Affiliation(s)
- Thomas E Frederick
- The Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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63
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Mann PA, Müller A, Xiao L, Pereira PM, Yang C, Ho Lee S, Wang H, Trzeciak J, Schneeweis J, dos Santos MM, Murgolo N, She X, Gill C, Balibar CJ, Labroli M, Su J, Flattery A, Sherborne B, Maier R, Tan CM, Black T, Önder K, Kargman S, Monsma FJ, Pinho MG, Schneider T, Roemer T. Murgocil is a highly bioactive staphylococcal-specific inhibitor of the peptidoglycan glycosyltransferase enzyme MurG. ACS Chem Biol 2013; 8:2442-51. [PMID: 23957438 DOI: 10.1021/cb400487f] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Modern medicine is founded on the discovery of penicillin and subsequent small molecules that inhibit bacterial peptidoglycan (PG) and cell wall synthesis. However, the discovery of new chemically and mechanistically distinct classes of PG inhibitors has become exceedingly rare, prompting speculation that intracellular enzymes involved in PG precursor synthesis are not 'druggable' targets. Here, we describe a β-lactam potentiation screen to identify small molecules that augment the activity of β-lactams against methicillin-resistant Staphylococcus aureus (MRSA) and mechanistically characterize a compound resulting from this screen, which we have named murgocil. We provide extensive genetic, biochemical, and structural modeling data demonstrating both in vitro and in whole cells that murgocil specifically inhibits the intracellular membrane-associated glycosyltransferase, MurG, which synthesizes the lipid II PG substrate that penicillin binding proteins (PBPs) polymerize and cross-link into the cell wall. Further, we demonstrate that the chemical synergy and cidality achieved between murgocil and the β-lactam imipenem is mediated through MurG dependent localization of PBP2 to the division septum. Collectively, these data validate our approach to rationally identify new target-specific bioactive β-lactam potentiation agents and demonstrate that murgocil now serves as a highly selective and potent chemical probe to assist our understanding of PG biosynthesis and cell wall biogenesis across Staphylococcal species.
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Affiliation(s)
- Paul A. Mann
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Anna Müller
- Institute
of Medical Microbiology, Immunology and Parasitology—Pharmaceutical
Microbiology Section, University of Bonn, Bonn, Germany
| | - Li Xiao
- Computational
Chemistry, Global Structure Chemistry, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Pedro M. Pereira
- Laboratory
of Bacterial Cell Biology, Instituto de Tecnologia Química
e Biológica, Universidade Nova de Lisboa, Avenida da República, 2781-901 Oeiras, Portugal
| | - Christine Yang
- Medicinal
Chemistry, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Sang Ho Lee
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Hao Wang
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Joanna Trzeciak
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Jonathan Schneeweis
- In Vitro Pharmacology, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Margarida Moreira dos Santos
- Laboratory
of Bacterial Cell Biology, Instituto de Tecnologia Química
e Biológica, Universidade Nova de Lisboa, Avenida da República, 2781-901 Oeiras, Portugal
| | - Nicholas Murgolo
- Research
Solutions, Bioinformatics, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Xinwei She
- Informatics
IT, Merck Inc., Boston, Massachusetts 02110, United States
| | - Charles Gill
- In Vivo Pharmacology, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Carl J. Balibar
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Marc Labroli
- Medicinal
Chemistry, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Jing Su
- Medicinal
Chemistry, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Amy Flattery
- In Vivo Pharmacology, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Brad Sherborne
- Computational
Chemistry, Global Structure Chemistry, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Richard Maier
- Procomcure Biotech GmbH, Krems a.d. Donau, Austria
- Division of Molecular
Dermatology, Department of Dermatology, Paracelsus Medical University, Salzburg, Austria
| | - Christopher M. Tan
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Todd Black
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Kamil Önder
- Procomcure Biotech GmbH, Krems a.d. Donau, Austria
- Division of Molecular
Dermatology, Department of Dermatology, Paracelsus Medical University, Salzburg, Austria
| | - Stacia Kargman
- In Vitro Pharmacology, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Frederick J Monsma
- In Vitro Pharmacology, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
| | - Mariana G. Pinho
- Laboratory
of Bacterial Cell Biology, Instituto de Tecnologia Química
e Biológica, Universidade Nova de Lisboa, Avenida da República, 2781-901 Oeiras, Portugal
| | - Tanja Schneider
- Institute
of Medical Microbiology, Immunology and Parasitology—Pharmaceutical
Microbiology Section, University of Bonn, Bonn, Germany
- German Centre for Infection Research (DZIF), partner site
Bonn-Cologne, Bonn, Germany
| | - Terry Roemer
- Infectious
Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033, United States
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Otero LH, Rojas-Altuve A, Llarrull LI, Carrasco-López C, Kumarasiri M, Lastochkin E, Fishovitz J, Dawley M, Hesek D, Lee M, Johnson JW, Fisher JF, Chang M, Mobashery S, Hermoso JA. How allosteric control of Staphylococcus aureus penicillin binding protein 2a enables methicillin resistance and physiological function. Proc Natl Acad Sci U S A 2013; 110:16808-13. [PMID: 24085846 PMCID: PMC3800995 DOI: 10.1073/pnas.1300118110] [Citation(s) in RCA: 185] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The expression of penicillin binding protein 2a (PBP2a) is the basis for the broad clinical resistance to the β-lactam antibiotics by methicillin-resistant Staphylococcus aureus (MRSA). The high-molecular mass penicillin binding proteins of bacteria catalyze in separate domains the transglycosylase and transpeptidase activities required for the biosynthesis of the peptidoglycan polymer that comprises the bacterial cell wall. In bacteria susceptible to β-lactam antibiotics, the transpeptidase activity of their penicillin binding proteins (PBPs) is lost as a result of irreversible acylation of an active site serine by the β-lactam antibiotics. In contrast, the PBP2a of MRSA is resistant to β-lactam acylation and successfully catalyzes the DD-transpeptidation reaction necessary to complete the cell wall. The inability to contain MRSA infection with β-lactam antibiotics is a continuing public health concern. We report herein the identification of an allosteric binding domain--a remarkable 60 Å distant from the DD-transpeptidase active site--discovered by crystallographic analysis of a soluble construct of PBP2a. When this allosteric site is occupied, a multiresidue conformational change culminates in the opening of the active site to permit substrate entry. This same crystallographic analysis also reveals the identity of three allosteric ligands: muramic acid (a saccharide component of the peptidoglycan), the cell wall peptidoglycan, and ceftaroline, a recently approved anti-MRSA β-lactam antibiotic. The ability of an anti-MRSA β-lactam antibiotic to stimulate allosteric opening of the active site, thus predisposing PBP2a to inactivation by a second β-lactam molecule, opens an unprecedented realm for β-lactam antibiotic structure-based design.
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Affiliation(s)
- Lisandro H. Otero
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano,” Consejo Superior de Investigaciones Cientificas, 28006 Madrid, Spain; and
| | - Alzoray Rojas-Altuve
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano,” Consejo Superior de Investigaciones Cientificas, 28006 Madrid, Spain; and
| | - Leticia I. Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Cesar Carrasco-López
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano,” Consejo Superior de Investigaciones Cientificas, 28006 Madrid, Spain; and
| | - Malika Kumarasiri
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Elena Lastochkin
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Jennifer Fishovitz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Matthew Dawley
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Dusan Hesek
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Jarrod W. Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Juan A. Hermoso
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano,” Consejo Superior de Investigaciones Cientificas, 28006 Madrid, Spain; and
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65
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Zhu J, Kaufmann GF. Quo vadis quorum quenching? Curr Opin Pharmacol 2013; 13:688-98. [DOI: 10.1016/j.coph.2013.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/26/2013] [Accepted: 07/01/2013] [Indexed: 01/27/2023]
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66
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O'Connell KMG, Hodgkinson JT, Sore HF, Welch M, Salmond GPC, Spring DR. Die Bekämpfung multiresistenter Bakterien: aktuelle Strategien zur Entdeckung neuer Antibiotika. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201209979] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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67
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O'Connell KMG, Hodgkinson JT, Sore HF, Welch M, Salmond GPC, Spring DR. Combating Multidrug-Resistant Bacteria: Current Strategies for the Discovery of Novel Antibacterials. Angew Chem Int Ed Engl 2013; 52:10706-33. [DOI: 10.1002/anie.201209979] [Citation(s) in RCA: 310] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/25/2013] [Indexed: 11/07/2022]
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Roemer T, Schneider T, Pinho MG. Auxiliary factors: a chink in the armor of MRSA resistance to β-lactam antibiotics. Curr Opin Microbiol 2013; 16:538-48. [PMID: 23895826 DOI: 10.1016/j.mib.2013.06.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/28/2013] [Accepted: 06/28/2013] [Indexed: 12/20/2022]
Abstract
Combination agents provide an important orthogonal approach to treat infectious diseases, particularly those caused by drug resistant pathogens. Indeed, applying a biologically 'rational' and systems-level paradigm to discover potent, selective, and synergistic agents would augment current (and arguably overly relied upon) empirical and serendipitous approaches to such discovery efforts. Here, we review the cellular mechanisms of β-lactam drug resistance and tolerance achieved amongst methicillin-resistant Staphylococcus aureus (MRSA) as well as their molecular targets and strategies to identify cognate inhibitors as potential combination agents to restore β-lactam efficacy against MRSA.
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Affiliation(s)
- Terry Roemer
- Infectious Disease Research, Merck Research Laboratories, Kenilworth, NJ 07033, USA.
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69
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Moran GJ, Abrahamian FM, LoVecchio F, Talan DA. Acute Bacterial Skin Infections: Developments Since the 2005 Infectious Diseases Society of America (IDSA) Guidelines. J Emerg Med 2013; 44:e397-412. [DOI: 10.1016/j.jemermed.2012.11.050] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 11/02/2012] [Indexed: 01/22/2023]
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70
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A positive interaction between inhibitors of protein synthesis and cefepime in the fight against methicillin-resistant Staphylococcus aureus. Eur J Clin Microbiol Infect Dis 2013; 32:899-907. [PMID: 23370969 DOI: 10.1007/s10096-013-1824-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
Quinupristin-dalfopristin (Q-D) synergizes with cefepime for the treatment of methicillin-resistant Staphylococcus aureus (MRSA). Here, we studied whether the synergism was restricted to MRSA and if it extended to non-beta-lactam cell wall inhibitors or to other inhibitors of protein synthesis. Three MRSA and two methicillin-susceptible S. aureus (MSSA) strains were tested, including an isogenic pair of mecA (-)/mecA (+) S. aureus Newman. The drug interactions were determined by fractional inhibitory concentration (FIC) indices and population analysis profiles. The antibacterial drugs that we used included beta-lactam (cefepime) and non-beta-lactam cell wall inhibitors (D-cycloserine, fosfomycin, vancomycin, teicoplanin), inhibitors of protein synthesis (Q-D, erythromycin, chloramphenicol, tetracycline, linezolid, fusidic acid), and polynucleotide inhibitors (cotrimoxazole, ciprofloxacin). The addition of each protein inhibitor to cefepime was synergistic (FIC ≤ 0.5) or additive (FIC > 0.5 but < 1) against MRSA, but mostly indifferent against MSSA (FIC ≥ 1 but ≤ 4). This segregation was not observed after adding cotrimoxazole or ciprofloxacin to cefepime. Population analysis profiles were performed on plates in the presence of increasing concentrations of the cell wall inhibitors plus 0.25 × minimum inhibitory concentration (MIC) of Q-D. Cefepime combined with Q-D was synergistic against MRSA, but D-cycloserine and glycopeptides were not. Thus, the synergism was specific to beta-lactam antibiotics. Moreover, the synergism was not lost against fem mutants, indicating that it acted at another level. The restriction of the beneficial effect to MRSA suggests that the functionality of penicillin-binding protein 2A (PBP2A) was affected, either directly or indirectly. Further studies are necessary in order to provide a mechanism for this positive interaction.
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71
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Farha MA, Leung A, Sewell EW, D’Elia MA, Allison SE, Ejim L, Pereira PM, Pinho MG, Wright GD, Brown ED. Inhibition of WTA synthesis blocks the cooperative action of PBPs and sensitizes MRSA to β-lactams. ACS Chem Biol 2013; 8:226-33. [PMID: 23062620 PMCID: PMC3552485 DOI: 10.1021/cb300413m] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
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Rising drug resistance is limiting treatment options
for infections
by methicillin-resistant Staphylococcus aureus (MRSA).
Herein we provide new evidence that wall teichoic acid (WTA) biogenesis
is a remarkable antibacterial target with the capacity to destabilize
the cooperative action of penicillin-binding proteins (PBPs) that
underlie β-lactam resistance in MRSA. Deletion of gene tarO, encoding the first step of WTA synthesis, resulted
in the restoration of sensitivity of MRSA to a unique profile of β-lactam
antibiotics with a known selectivity for penicillin binding protein
2 (PBP2). Of these, cefuroxime was used as a probe to screen for previously
approved drugs with a cryptic capacity to potentiate its activity
against MRSA. Ticlopidine, the antiplatelet drug Ticlid, strongly
potentiated cefuroxime, and this synergy was abolished in strains
lacking tarO. The combination was also effective
in a Galleria mellonella model of infection. Using
both genetic and biochemical strategies, we determined the molecular
target of ticlopidine as the N-acetylglucosamine-1-phosphate
transferase encoded in gene tarO and provide evidence
that WTA biogenesis represents an Achilles heel supporting the cooperative
function of PBP2 and PBP4 in creating highly cross-linked muropeptides
in the peptidoglycan of S. aureus. This approach
represents a new paradigm to tackle MRSA infection.
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Affiliation(s)
- Maya A. Farha
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Alexander Leung
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Edward W. Sewell
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Michael A. D’Elia
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Sarah E. Allison
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Linda Ejim
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Pedro M. Pereira
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Mariana G. Pinho
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Gerard D. Wright
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Eric D. Brown
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
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72
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Stojanov M, Sakwinska O, Moreillon P. Expression of SCCmec cassette chromosome recombinases in methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. J Antimicrob Chemother 2012; 68:749-57. [PMID: 23249841 DOI: 10.1093/jac/dks494] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Methicillin resistance in staphylococci is mediated by the mecA gene, which is carried on the staphylococcal cassette chromosome mec (SCCmec). SCCmec is responsible for vertical and horizontal transfer of methicillin resistance. Horizontal transfer implies first SCCmec excision from the chromosome. Site-specific excision is catalysed by the Ccr recombinases, which are encoded by ccrAB genes located on the cassette. The aim of this study is to determine the promoter activity of ccrAB genes in individual cells of methicillin-resistant Staphylococcus aureus (N315, COL and MW2) and Staphylococcus epidermidis (RP62A). One mutant cured of its SCCmec (N315EX) was also used. Exposure to various stresses was included in the study. METHODS For each strain, translational promoter-green fluorescent protein (gfp) fusions were used to assess the levels of ccr promoter activity in individual cells. Analyses were performed using epifluorescence microscopy and flow cytometry. RESULTS ccr promoter activity was observed in only a small percentage of cell populations. This 'bistable' phenotype was strain dependent (GFP was expressed in N315 and RP62A, but not in COL and MW2) and growth dependent (GFP-expressing cells decreased from approximately 3% to 1% between logarithmic and stationary growth phases). The ccr promoter of strain N315 displayed normal promoter activity when expressed in SCCmec-negative N315EX. Likewise, the ccr promoter of strain COL (which was inactive in COL) showed normal N315-like activity when transformed into N315 and N315EX. CONCLUSIONS SCCmec excision operates through bistability, favouring a small fraction of cells to 'sacrifice' their genomic islands for transfer, while the rest of the population remains intact. Determinants responsible for the activity of the ccr promoter were not located on SCCmec, but were elsewhere on the genome. Thus, the staphylococcal chromosome plays a key role in determining SCCmec stability and transferability.
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Affiliation(s)
- M Stojanov
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
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73
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Abstract
Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many--and quite possibly all--bacteria, the peptidoglycan fragments are recovered and recycled. Although cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall-targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall-recycling inhibitors.
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Affiliation(s)
- Jarrod W Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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74
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Early insights into the interactions of different β-lactam antibiotics and β-lactamase inhibitors against soluble forms of Acinetobacter baumannii PBP1a and Acinetobacter sp. PBP3. Antimicrob Agents Chemother 2012; 56:5687-92. [PMID: 22908165 DOI: 10.1128/aac.01027-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Acinetobacter baumannii is an increasingly problematic pathogen in United States hospitals. Antibiotics that can treat A. baumannii are becoming more limited. Little is known about the contributions of penicillin binding proteins (PBPs), the target of β-lactam antibiotics, to β-lactam-sulbactam susceptibility and β-lactam resistance in A. baumannii. Decreased expression of PBPs as well as loss of binding of β-lactams to PBPs was previously shown to promote β-lactam resistance in A. baumannii. Using an in vitro assay with a reporter β-lactam, Bocillin, we determined that the 50% inhibitory concentrations (IC(50)s) for PBP1a from A. baumannii and PBP3 from Acinetobacter sp. ranged from 1 to 5 μM for a series of β-lactams. In contrast, PBP3 demonstrated a narrower range of IC(50)s against β-lactamase inhibitors than PBP1a (ranges, 4 to 5 versus 8 to 144 μM, respectively). A molecular model with ampicillin and sulbactam positioned in the active site of PBP3 reveals that both compounds interact similarly with residues Thr526, Thr528, and Ser390. Accepting that many interactions with cell wall targets are possible with the ampicillin-sulbactam combination, the low IC(50)s of ampicillin and sulbactam for PBP3 may contribute to understanding why this combination is effective against A. baumannii. Unraveling the contribution of PBPs to β-lactam susceptibility and resistance brings us one step closer to identifying which PBPs are the best targets for novel β-lactams.
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75
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Morosini MI, Cercenado E, Ardanuy C, Torres C. Detección fenotípica de mecanismos de resistencia en microorganismos grampositivos. Enferm Infecc Microbiol Clin 2012; 30:325-32. [DOI: 10.1016/j.eimc.2011.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 09/08/2011] [Indexed: 10/14/2022]
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76
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Llarrull LI, Mobashery S. Dissection of events in the resistance to β-lactam antibiotics mediated by the protein BlaR1 from Staphylococcus aureus. Biochemistry 2012; 51:4642-9. [PMID: 22616850 DOI: 10.1021/bi300429p] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A heterologous expression system was used to evaluate activation of BlaR1, a sensor/signal transducer protein of Staphylococcus aureus with a central role in resistance to β-lactam antibiotics. In the absence of other S. aureus proteins that might respond to antibiotics and participate in signal transduction events, we documented that BlaR1 fragmentation is autolytic, that it occurs in the absence of antibiotics, and that BlaR1 directly degrades BlaI, the gene repressor of the system. Furthermore, we disclosed that this proteolytic activity is metal ion-dependent and that it is not modulated directly by acylation of the sensor domain by β-lactam antibiotics.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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77
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Impedimetric detection of single-stranded PCR products derived from methicillin resistant Staphylococcus aureus (MRSA) isolates. Biosens Bioelectron 2012; 34:178-84. [DOI: 10.1016/j.bios.2012.01.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 01/25/2012] [Accepted: 01/29/2012] [Indexed: 11/21/2022]
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78
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Boudreau MA, Fisher JF, Mobashery S. Messenger functions of the bacterial cell wall-derived muropeptides. Biochemistry 2012; 51:2974-90. [PMID: 22409164 DOI: 10.1021/bi300174x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bacterial muropeptides are soluble peptidoglycan structures central to recycling of the bacterial cell wall and messengers in diverse cell signaling events. Bacteria sense muropeptides as signals that antibiotics targeting cell-wall biosynthesis are present, and eukaryotes detect muropeptides during the innate immune response to bacterial infection. This review summarizes the roles of bacterial muropeptides as messengers, with a special emphasis on bacterial muropeptide structures and the relationship of structure to the biochemical events that the muropeptides elicit. Muropeptide sensing and recycling in both Gram-positive and Gram-negative bacteria are discussed, followed by muropeptide sensing by eukaryotes as a crucial event in the innate immune response of insects (via peptidoglycan-recognition proteins) and mammals (through Nod-like receptors) to bacterial invasion.
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Affiliation(s)
- Marc A Boudreau
- Department of Chemistry and Biochemistry, Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556, USA
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79
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mecA-positive Staphylococcus aureus with low-level oxacillin MIC in Taiwan. J Clin Microbiol 2012; 50:1679-83. [PMID: 22378906 DOI: 10.1128/jcm.06711-11] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Although the presence of mecA is the genotypic determinant of methicillin-resistant Staphylococcus aureus (MRSA), certain MRSA strains, especially community-associated MRSA (C-MRSA), can display an oxacillin MIC in the Clinical and Laboratory Standards Institute susceptible breakpoint range (≤ 2 μg/ml). Among 91 and 180 isolates thought to be methicillin-susceptible S. aureus (MSSA) with oxacillin MICs of 2 and 1 μg/ml as determined by the Sensititre broth microdilution test initially, 52 (57.1%) and 6 (3.3%), respectively, were mecA positive. These mecA-positive low-oxacillin-MIC isolates belong to the dominant Taiwan C-MRSA clone (clonal complex [CC] 59), 56 of which carried SCCmec type V and were pvl positive, and 43 of which belonged to spa CC t437. All 271 isolates were retested by Sensititre, as well as by Vitek II and disk diffusion (DD). Based on the oxacillin results, the sensitivities of the Sensititre, Vitek II, and DD methods were 48.3% (28/58), 46.6% (27/58), and 89.6% (52/58), respectively. Although cefoxitin was better at detecting these isolates, 12.1, 10.4, and 5.2% of these isolates were still misidentified as MSSA by Sensititre, Vitek II, and DD, respectively. These results highlight the difficulty in the accurate identification of MRSA with borderline oxacillin MICs in the CC59:SCCmec V clone, which likely has contributed to its spread in the health care and community settings. Since this clone has now been detected in other countries, and since other C-MRSA lineages have also been found to have low-level β-lactam resistance, the findings of the present study may be relevant to other regions. Further studies are warranted to determine the extent and clinical impact of such misidentification.
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80
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Hao H, Cheng G, Dai M, Wu Q, Yuan Z. Inhibitors targeting on cell wall biosynthesis pathway of MRSA. MOLECULAR BIOSYSTEMS 2012; 8:2828-38. [DOI: 10.1039/c2mb25188d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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81
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Skariyachan S, Krishnan RS, Siddapa SB, Salian C, Bora P, Sebastian D. Computer aided screening and evaluation of herbal therapeutics against MRSA infections. Bioinformation 2011; 7:222-33. [PMID: 22125390 PMCID: PMC3218416 DOI: 10.6026/97320630007222] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 10/11/2011] [Indexed: 01/09/2023] Open
Abstract
Methicillin resistant Staphylococcus aureus (MRSA), a pathogenic bacterium that causes life threatening outbreaks such as community-onset and nosocomial infections has emerged as 'superbug'. The organism developed resistance to all classes of antibiotics including the best known Vancomycin (VRSA). Hence, there is a need to develop new therapeutic agents. This study mainly evaluates the potential use of botanicals against MRSA infections. Computer aided design is an initial platform to screen novel inhibitors and the data finds applications in drug development. The drug-likeness and efficiency of various herbal compounds were screened by ADMET and docking studies. The virulent factor of most of the MRSA associated infections are Penicillin Binding Protein 2A (PBP2A) and Panton-Valentine Leukocidin (PVL). Hence, native structures of these proteins (PDB: 1VQQ and 1T5R) were used as the drug targets. The docking studies revealed that the active component of Aloe vera, β-sitosterol (3S, 8S, 9S, 10R, 13R, 14S, 17R) -17- [(2R, 5R)-5-ethyl-6-methylheptan-2-yl] -10, 13-dimethyl 2, 3, 4, 7, 8, 9, 11, 12, 14, 15, 16, 17- dodecahydro-1H-cyclopenta [a] phenanthren-3-ol) showed best binding energies of -7.40 kcal/mol and -6.34 kcal/mol for PBP2A and PVL toxin, respectively. Similarly, Meliantriol (1S-1-[ (2R, 3R, 5R)-5-hydroxy-3-[(3S, 5R, 9R, 10R, 13S, 14S, 17S)-3-hydroxy 4, 4, 10, 13, 14-pentamethyl-2, 3, 5, 6, 9, 11, 12, 15, 16, 17-decahydro-1H-cyclopenta[a] phenanthren-17-yl] oxolan-2-yl] -2- methylpropane-1, 2 diol), active compound in Azadirachta indica (Neem) showed the binding energies of -6.02 kcal/mol for PBP2A and -8.94 for PVL toxin. Similar studies were conducted with selected herbal compound based on pharmacokinetic properties. All in silico data tested in vitro concluded that herbal extracts of Aloe-vera, Neem, Guava (Psidium guajava), Pomegranate (Punica granatum) and tea (Camellia sinensis) can be used as therapeutics against MRSA infections.
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Affiliation(s)
- Sinosh Skariyachan
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bangalore, India
| | - Rao Shruti Krishnan
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bangalore, India
| | | | - Chithra Salian
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bangalore, India
| | - Prerana Bora
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bangalore, India
| | - Denoj Sebastian
- Department of Microbiology, University of Calicut, Kerala, India
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Richter SS, Heilmann KP, Dohrn CL, Riahi F, Costello AJ, Kroeger JS, Biek D, Critchley IA, Diekema DJ, Doern GV. Activity of ceftaroline and epidemiologic trends in Staphylococcus aureus isolates collected from 43 medical centers in the United States in 2009. Antimicrob Agents Chemother 2011; 55:4154-60. [PMID: 21709080 PMCID: PMC3165333 DOI: 10.1128/aac.00315-11] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/27/2011] [Accepted: 06/20/2011] [Indexed: 11/20/2022] Open
Abstract
A Staphylococcus aureus surveillance program was initiated in the United States to examine the in vitro activity of ceftaroline and epidemiologic trends. Susceptibility testing by Clinical and Laboratory Standards Institute broth microdilution was performed on 4,210 clinically significant isolates collected in 2009 from 43 medical centers. All isolates were screened for mecA by PCR and evaluated by pulsed-field gel electrophoresis. Methicillin-resistant S. aureus (MRSA) were analyzed for Panton-Valentine leukocidin (PVL) genes and the staphylococcal cassette chromosome mec (SCCmec) type. All isolates had ceftaroline MICs of ≤2 μg/ml with an MIC(50) of 0.5 and an MIC(90) of 1 μg/ml. The overall resistance rates, expressed as the percentages of isolates that were intermediate and resistant (or nonsusceptible), were as follows: ceftaroline, 1.0%; clindamycin, 30.2% (17.4% MIC ≥ 4 μg/ml; 12.8% inducible); daptomycin, 0.2%; erythromycin, 65.5%; levofloxacin, 39.9%; linezolid, 0.02%; oxacillin, 53.4%; tetracycline, 4.4%; tigecycline, 0%; trimethoprim-sulfamethoxazole, 1.6%; vancomycin, 0%; and high-level mupirocin, 2.2%. The mecA PCR was positive for 53.4% of the isolates. The ceftaroline MIC(90)s were 0.25 μg/ml for methicillin-susceptible S. aureus and 1 μg/ml for MRSA. Among the 2,247 MRSA isolates, 51% were USA300 (96.9% PVL positive, 99.7% SCCmec type IV) and 17% were USA100 (93.4% SCCmec type II). The resistance rates for the 1,137 USA300 MRSA isolates were as follows: erythromycin, 90.9%; levofloxacin, 49.1%; clindamycin, 7.6% (6.2% MIC ≥ 4 μg/ml; 1.4% inducible); tetracycline, 3.3%; trimethoprim-sulfamethoxazole, 0.8%; high-level mupirocin, 2.7%; daptomycin, 0.4%; and ceftaroline and linezolid, 0%. USA300 is the dominant clone causing MRSA infections in the United States. Ceftaroline demonstrated potent in vitro activity against recent S. aureus clinical isolates, including MRSA, daptomycin-nonsusceptible, and linezolid-resistant strains.
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Affiliation(s)
- Sandra S Richter
- Department of Clinical Pathology, Cleveland Clinic, 9500 Euclid Avenue, L40, Cleveland, OH 44195, USA.
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83
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Borbulevych O, Kumarasiri M, Wilson B, Llarrull LI, Lee M, Hesek D, Shi Q, Peng J, Baker BM, Mobashery S. Lysine Nzeta-decarboxylation switch and activation of the beta-lactam sensor domain of BlaR1 protein of methicillin-resistant Staphylococcus aureus. J Biol Chem 2011; 286:31466-72. [PMID: 21775440 DOI: 10.1074/jbc.m111.252189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The integral membrane protein BlaR1 of methicillin-resistant Staphylococcus aureus senses the presence of β-lactam antibiotics in the milieu and transduces the information to the cytoplasm, where the biochemical events that unleash induction of antibiotic resistance mechanisms take place. We report herein by two-dimensional and three-dimensional NMR experiments of the sensor domain of BlaR1 in solution and by determination of an x-ray structure for the apo protein that Lys-392 of the antibiotic-binding site is posttranslationally modified by N(ζ)-carboxylation. Additional crystallographic and NMR data reveal that on acylation of Ser-389 by antibiotics, Lys-392 experiences N(ζ)-decarboxylation. This unique process, termed the lysine N(ζ)-decarboxylation switch, arrests the sensor domain in the activated ("on") state, necessary for signal transduction and all the subsequent biochemical processes. We present structural information on how this receptor activation process takes place, imparting longevity to the antibiotic-receptor complex that is needed for the induction of the antibiotic-resistant phenotype in methicillin-resistant S. aureus.
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Affiliation(s)
- Oleg Borbulevych
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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84
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Qiu J, Li H, Meng H, Hu C, Li J, Luo M, Dong J, Wang X, Wang J, Deng Y, Deng X. Impact of luteolin on the production of alpha-toxin by Staphylococcus aureus. Lett Appl Microbiol 2011; 53:238-43. [PMID: 21671964 DOI: 10.1111/j.1472-765x.2011.03098.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To investigate the influence of subinhibitory concentrations of luteolin on the production of α-toxin in Staphylococcus aureus. METHODS AND RESULTS The minimal inhibitory concentrations (MICs) were determined using a broth microdilution method, and the MICs of luteolin against the tested Staph. aureus strains ranged from 16 to 64 μg ml(-1). Haemolysis, Western blot and real-time reverse transcription (RT)-PCR assays were used to evaluate the effect of luteolin on Staph. aureusα-toxin secretion and on the level of gene expression, respectively. The data indicated that subinhibitory concentrations of luteolin dose dependently decreased the production of α-toxin in both meticillin-sensitive Staph. aureus (MSSA) and meticillin-resistant Staph. aureus (MRSA). Furthermore, the transcriptional levels of agr (accessory gene regulator) in Staph. aureus were also inhibited by luteolin. CONCLUSIONS Luteolin decreases the production and/or secretion of α-toxin in Staph. aureus; the reduced production may be dependent, in part, upon the luteolin-induced inhibition of the agr locus. SIGNIFICANCE AND IMPACT OF THE STUDY The findings indicate that luteolin may be used as a basis for the development of antimicrobial agents aimed at bacterial virulence factors.
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Affiliation(s)
- J Qiu
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun, China
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85
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Kaushik D, Rathi S, Jain A. Ceftaroline: a comprehensive update. Int J Antimicrob Agents 2011; 37:389-95. [PMID: 21420284 DOI: 10.1016/j.ijantimicag.2011.01.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/14/2010] [Accepted: 01/19/2011] [Indexed: 10/18/2022]
Abstract
Ceftaroline is a novel broad-spectrum cephalosporin antibiotic currently under US Food and Drug Administration (FDA) review for a new drug application (NDA), filed by Cerexa, Inc. (a wholly owned subsidiary of Forest Laboratories), for the treatment of complicated skin and skin-structure infections (cSSSIs) and community-associated pneumonia (CAP). The antibiotic acts by binding to penicillin-binding proteins in bacteria, consistent with other β-lactams. The antimicrobial spectrum of ceftaroline ranges from aerobic and anaerobic Gram-positive bacteria, including drug-resistant isolates of staphylococci, i.e. heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA), vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA), to anaerobic Gram-negative pathogens such as Moraxella catarrhalis and Haemophilus influenzae (including β-lactamase-positive strains), as well as bacteria with multiple resistance phenotypes. Ceftaroline fosamil is the prodrug that is rapidly dephosphorylated by in vivo plasma phosphatases to the active drug ceftaroline, which follows a two-compartmental pharmacokinetic model and is eliminated primarily by renal excretion, with a plasma half-life of ca. 2.5 h. Ceftaroline is well tolerated, which is consistent with its good safety profile similar to other cephalosporins in clinical trials. Thus, it would be a promising drug to fight multidrug-resistant superbugs such as S. aureus and Streptococcus pneumoniae for the treatment of cSSSIs and CAP.
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Affiliation(s)
- Darpan Kaushik
- Department of Pharmaceutical Chemistry, Rajendra Institute of Technology & Sciences, 4th Mile Stone, Hisar Road, Sirsa 125055, Haryana, India.
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86
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Laudano JB. Ceftaroline fosamil: a new broad-spectrum cephalosporin. J Antimicrob Chemother 2011; 66 Suppl 3:iii11-8. [PMID: 21482565 DOI: 10.1093/jac/dkr095] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Ceftaroline fosamil, the prodrug of the active metabolite, ceftaroline, is a new, broad-spectrum cephalosporin recently approved in the USA for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) and community-acquired bacterial pneumonia (CABP). Ceftaroline has potent in vitro activity against Gram-positive organisms, including methicillin-resistant Staphylococcus aureus and Streptococcus pneumoniae, as well as common Gram-negative organisms. The high affinity of ceftaroline for penicillin-binding proteins is responsible for the potent activity observed against clinically relevant pathogens. With respect to the treatment of CABP, the activity of ceftaroline against pathogens such as S. pneumoniae, S. aureus, Haemophilus influenzae and Moraxella catarrhalis demonstrates coverage across a broad range of pathogens typically encountered in clinical practice. Ceftaroline is also very active against common pathogens seen in ABSSSIs such as S. aureus (methicillin-susceptible S. aureus and methicillin-resistant S. aureus) and Streptococcus pyogenes. Ceftaroline exhibits a dose-proportional pharmacokinetic profile, similar to other renally excreted cephalosporins, and has a well-tolerated safety profile consistent with the cephalosporin class. Ceftaroline fosamil is compatible via Y-site administration with many other commonly administered parenteral drugs.
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Affiliation(s)
- Joseph B Laudano
- Medical Affairs, Forest Research Institute, Harborside Financial Center, Jersey City, NJ 07311, USA.
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87
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Drusano GL. What are the properties that make an antibiotic acceptable for therapy of community-acquired pneumonia? J Antimicrob Chemother 2011; 66 Suppl 3:iii61-7. [PMID: 21482571 DOI: 10.1093/jac/dkr100] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The factors associated with identifying an appropriate dose and schedule of an antimicrobial agent for treatment of hospitalized, seriously ill patients with pneumonia are straightforward. Information is required about the potency of the agent for typical pathogens likely to be encountered with pneumonia. It is helpful to understand the utility of the agent against pathogens that express resistance to older antimicrobial agents. The agent must be able to gain access to the site of infection at the dose and schedule chosen and at concentrations high enough to attain microbiologically effective targets [e.g. 1 or 2 log(10) (cfu/g) bacterial cell kill, accounting for between-patient variability]. Finally, therapeutic concentrations should be attained quickly at the primary site of infection to optimize clinical outcomes. When considering all of these factors, it is expected that ceftaroline fosamil will be a valuable addition to the therapeutic armamentarium for management of community-acquired pneumonia.
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88
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Duplessis C, Crum-Cianflone NF. Ceftaroline: A New Cephalosporin with Activity against Methicillin-Resistant Staphylococcus aureus (MRSA). CLINICAL MEDICINE REVIEWS IN THERAPEUTICS 2011; 3:a2466. [PMID: 21785568 PMCID: PMC3140339 DOI: 10.4137/cmrt.s1637] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Microbial resistance has reached alarming levels, threatening to outpace the ability to counter with more potent antimicrobial agents. In particular, methicillin-resistant Staphylococcus aureus (MRSA) has become a leading cause of skin and soft-tissue infections and PVL-positive strains have been associated with necrotizing pneumonia. Increasing reports of growing resistance to glycopeptides have been noted, further limiting the efficacy of standard antibiotics, such as vancomycin. Ceftaroline is a novel fifth-generation cephalosporin, which exhibits broad-spectrum activity against Gram-positive bacteria, including MRSA and extensively-resistant strains, such as vancomycin-intermediate S. aureus (VISA), heteroresistant VISA (hVISA), and vancomycin-resistant S. aureus (VRSA). In addition to being an exciting new agent in the anti-MRSA armamentarium, ceftaroline provides efficacy against many respiratory pathogens including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Ceftaroline (600 mg intravenously every 12 hours) has been shown effective in phase III studies in the treatment of complicated skin and soft tissue infections and community-acquired pneumonia. To date, this unique antibiotic exhibits a low propensity for inducing resistance and has a good safety profile, although further post-marketing data and clinical experience are needed. In summary, ceftaroline provides an additional option for the management of complex multidrug resistant infections, including MRSA.
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Affiliation(s)
- Christopher Duplessis
- Infectious Disease Division, Naval Medical Center San Diego, San Diego, CA United States
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89
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Campbell J, Singh AK, Santa Maria JP, Kim Y, Brown S, Swoboda JG, Mylonakis E, Wilkinson BJ, Walker S. Synthetic lethal compound combinations reveal a fundamental connection between wall teichoic acid and peptidoglycan biosyntheses in Staphylococcus aureus. ACS Chem Biol 2011; 6:106-16. [PMID: 20961110 DOI: 10.1021/cb100269f] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methicillin resistance in Staphylococcus aureus depends on the production of mecA, which encodes penicillin-binding protein 2A (PBP2A), an acquired peptidoglycan transpeptidase (TP) with reduced susceptibility to β-lactam antibiotics. PBP2A cross-links nascent peptidoglycan when the native TPs are inhibited by β-lactams. Although mecA expression is essential for β-lactam resistance, it is not sufficient. Here we show that blocking the expression of wall teichoic acids (WTAs) by inhibiting the first enzyme in the pathway, TarO, sensitizes methicillin-resistant S. aureus (MRSA) strains to β-lactams even though the β-lactam-resistant transpeptidase, PBP2A, is still expressed. The dramatic synergy between TarO inhibitors and β-lactams is noteworthy not simply because strategies to overcome MRSA are desperately needed but because neither TarO nor the activities of the native TPs are essential in MRSA strains. The "synthetic lethality" of inhibiting TarO and the native TPs suggests a functional connection between ongoing WTA expression and peptidoglycan assembly in S. aureus. Indeed, transmission electron microscopy shows that S. aureus cells blocked in WTA synthesis have extensive defects in septation and cell separation, indicating dysregulated cell wall assembly and degradation. Our studies imply that WTAs play a fundamental role in S. aureus cell division and raise the possibility that synthetic lethal compound combinations may have therapeutic utility for overcoming antibiotic-resistant bacterial infections.
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Affiliation(s)
- Jennifer Campbell
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Atul K. Singh
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - John P. Santa Maria
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Younghoon Kim
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Stephanie Brown
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Jonathan G. Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Brian J. Wilkinson
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
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90
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Drusano GL. Pharmacodynamics of ceftaroline fosamil for complicated skin and skin structure infection: rationale for improved anti-methicillin-resistant Staphylococcus aureus activity. J Antimicrob Chemother 2010; 65 Suppl 4:iv33-9. [PMID: 21115453 DOI: 10.1093/jac/dkq253] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ceftaroline fosamil is a new β-lactam antibiotic with an altered 3' side chain that allows it to interact with penicillin-binding protein (PBP) 2a, resulting in lower MIC values for methicillin-resistant Staphylococcus aureus (MRSA). Large MRSA collections repeatedly demonstrate MIC₉₀ values of 1 mg/L. The pharmacokinetics for ceftaroline fosamil are straightforward and reminiscent of many other cephalosporin antibiotics, with a terminal half-life of ∼2.6 h. Pharmacodynamic evaluation demonstrates that relatively short free drug T > MIC results in stasis or 1 log₁₀ cfu/g bacterial kill (mean values for four S. aureus isolates of 26% and 33% of the dosing interval, respectively). Monte Carlo simulation demonstrated high expected target attainment rates (> 97%) and clinical trial data showed clinically evaluable and microbiologically evaluable cure rates (96.7%) that are highly concordant with the pharmacodynamic analyses. Clinical trial data for ceftaroline fosamil are in excellent concordance with the pharmacodynamic analysis. Ceftaroline fosamil at a dose of 600 mg administered intravenously every 12 h is highly likely to be successful in clinical practice for treatment of complicated skin and skin structure infections.
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91
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Jones RN, Mendes RE, Sader HS. Ceftaroline activity against pathogens associated with complicated skin and skin structure infections: results from an international surveillance study. J Antimicrob Chemother 2010; 65 Suppl 4:iv17-31. [PMID: 21115451 DOI: 10.1093/jac/dkq252] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To assess the spectrum and potency of ceftaroline, a novel anti-methicillin-resistant staphylococcal cephalosporin, against a 2008 surveillance collection of clinical isolates from patients in the USA and Europe. METHODS A collection of 14 169 isolates of various bacterial species from complicated skin and skin structure infections (cSSSIs) was tested for susceptibility to ceftaroline and 19 comparator agents in a central reference laboratory using CLSI broth microdilution methods. Organisms were received from 55 medical centres; 27 in the USA and 28 in Europe (12 countries, including Israel). The clonality of isolates of Staphylococcus aureus with elevated ceftaroline MICs (4 mg/L) was determined by PFGE and single and multilocus sequence typing, and the mechanism of ceftaroline non-susceptibility was assessed by molecular methods (PCR amplification and sequencing). RESULTS Ceftaroline, the active component of the parenteral prodrug ceftaroline fosamil, was active against 2988 methicillin-resistant S. aureus (MRSA) isolates, with an MI₉₀ of 1 mg/L. The MIC₉₀ for methicillin-susceptible strains was 0.25-0.5 mg/L. Ceftaroline was additionally active against coagulase-negative staphylococci (MIC₉₀, 0.5-1 mg/L), Enterococcus faecalis (MIC₅₀, 2 mg/L), β-haemolytic and viridans group streptococci (MIC₉₀, 0.015-0.25 mg/L) and three commonly isolated Enterobacteriaceae (Escherichia coli, Klebsiella spp. and Proteus mirabilis; MIC₉₀ values of 0.25 to > 16 mg/L). All but four isolates of MRSA (0.13%) had ceftaroline MIC values of ≤ 2 mg/L. The isolates for which ceftaroline MICs were 4 mg/L were clonal (single Greek hospital) and had detectable mecA mutations (N146K, N204K, E150K and H351N). CONCLUSIONS The ceftaroline yearly (2008) surveillance for the USA and Europe documented low MIC₅₀/₉₀ values for MRSA isolates at 1/1 and 1/2 mg/L, respectively. Ceftaroline demonstrated promising potency and coverage against Gram-positive and -negative pathogens known to cause cSSSIs, including MRSA and β-haemolytic streptococci.
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92
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Llarrull LI, Prorok M, Mobashery S. Binding of the gene repressor BlaI to the bla operon in methicillin-resistant Staphylococcus aureus. Biochemistry 2010; 49:7975-7. [PMID: 20722402 DOI: 10.1021/bi101177a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The expression of the gene products in many methicillin-resistant Staphylococcus aureus (MRSA) strains is regulated by the gene repressor BlaI. Here we show that BlaI is a mixture of monomer and dimer at in vivo concentrations, binds to the operator regions preferentially as a monomeric protein, and the measured dissociation constants and in vivo concentrations account for the basal level transcription of the resistance genes. These observations for the first time provide a quantitative picture of the processes that take place in the cytoplasm that lead to the induction of antibiotic resistance factors to counter the challenge by β-lactams.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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93
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Llarrull LI, Testero SA, Fisher JF, Mobashery S. The future of the β-lactams. Curr Opin Microbiol 2010; 13:551-7. [PMID: 20888287 DOI: 10.1016/j.mib.2010.09.008] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 09/08/2010] [Accepted: 09/09/2010] [Indexed: 11/15/2022]
Abstract
In the 80 years since their discovery the β-lactam antibiotics have progressed through structural generations, each in response to the progressive evolution of bacterial resistance mechanisms. The generational progression was driven by the ingenious, but largely empirical, manipulation of structure by medicinal chemists. Nonetheless, the true creative force in these efforts was Nature, and as the discovery of new β-lactams from Nature has atrophied while at the same time multi-resistant and opportunistic bacterial pathogens have burgeoned, the time for empirical drug discovery has passed. We concisely summarize recent developments with respect to bacterial resistance, the identity of the new β-lactams, and the emerging non-empirical strategies that will ensure that this incredible class of antibiotics has a future.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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94
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Abstract
An increasing proportion of Staphylococcus aureus infections are caused by methicillin-resistant S aureus. Treatment of infections caused by this organism is challenging, especially because therapy with vancomycin, the traditional antibiotic of choice for methicillin-resistant S aureus infections, is associated with an increasing frequency of treatment failure, and vancomycin insensitive and vancomycin-resistant strains have emerged. In addition, Enterococcus sp. isolated from human infections are increasingly resistant to multiple antimicrobial agents. Newer drugs available for treatment of resistant Gram-positive bacterial infections in the United States include linezolid, daptomycin, tigecycline and telavancin. The precise role for these newer agents is still evolving. Organisms resistant to each of these antimicrobials have emerged. New drugs in development include cephalosporins and carbapenems with MRSA activity.
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95
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Nadig S, Ramachandra Raju S, Arakere G. Epidemic meticillin-resistant Staphylococcus aureus (EMRSA-15) variants detected in healthy and diseased individuals in India. J Med Microbiol 2010; 59:815-821. [DOI: 10.1099/jmm.0.017632-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This study provides what we believe to be the first report of the presence of EMRSA-15 and its variants isolated from nasal swabs from 13 healthy and diseased individuals in India. The majority of the isolates belonged to staphylococcal cassette chromosome mec (SCCmec) type IV and spa type t852, whilst four isolates were non-typable and heterotypic for the presence of the mecA gene. All non-typable isolates were positive for the orfX gene by PCR and belonged to spa types t005 and t2986. They may have variant SCCmec cassettes indicating genetic changes occurring in the Indian EMRSA-15. All isolates were positive for Panton–Valentine leukocidin and toxic shock syndrome toxin, which is a cause for concern. In addition to soft-tissue infections, the EMRSA-15 isolates from patients were also responsible for meningitis and brain abscesses, which is quite rare.
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Affiliation(s)
- Savitha Nadig
- Sir Dorabji Tata Centre for Research in Tropical Diseases, Innovation Centre, Indian Institute of Science Campus, Bangalore 560012, India
| | - Shilpa Ramachandra Raju
- Sir Dorabji Tata Centre for Research in Tropical Diseases, Innovation Centre, Indian Institute of Science Campus, Bangalore 560012, India
| | - Gayathri Arakere
- Sir Dorabji Tata Centre for Research in Tropical Diseases, Innovation Centre, Indian Institute of Science Campus, Bangalore 560012, India
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