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Miller D. Update on the Epidemiology and Antibiotic Resistance of Ocular Infections. Middle East Afr J Ophthalmol 2017; 24:30-42. [PMID: 28546690 PMCID: PMC5433126 DOI: 10.4103/meajo.meajo_276_16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
PURPOSE: The purpose of this review is to provide an update on the epidemiology and current antibiotic-resistant threats in ophthalmology. METHODS: Trends in frequency and antibiotic-nonsusceptible profiles during an 11 year-period (2005–2015) were evaluated and compared with the 5-year Antibiotic Resistance Monitoring in Ocular Microorganism (ARMOR) study. RESULTS: Trends in the current review confirmed the continued high rates of fluoroquinolone nonsusceptbility circulating among ocular methicillin-susceptible Staphylococcus aureus, methicillin-susceptible Staphylococcus epidermidis, methicillin-resistant S. aureus, and methicillin-resistant S. epidermidis isolates as well as the detection of uncommon, but emerging resistance (<5%) for Streptococcus pneumoniae, Streptococcus viridans group, Haemophilus influenzae, and Pseudomonas aeruginosa. We documented significant differences in empirical fluoroquinolone and aminoglycoside coverage for the top three ocular pathogens (coagulase-negative staphylococci, S. aureus, and P. aeruginosa) in general and for corneal isolates between the Miami and the ARMOR studies. Collectively, the coverage for Miami was 74% versus 65.9% for ARMOR (P < 0.0001, 5.3674–10.8042) for ciprofloxacin and 95.9% versus 84.2% for aminoglycosides (gentamicin/tobramycin) (P < 0.0001, 9.9925–13.3974). Monotherapy coverage for ciprofloxacin and levofloxacin for the most recent 5 years (2011–2015) was 76.6% and 77.1%, respectively. Combination therapy with a fluoroquinolone and vancomycin and/or vancomycin and an aminoglycoside provided coverage for 99% and 98% of the isolates, respectively. CONCLUSION: The etiology of ocular pathogens is patient, source, and geography specific. The true incidence and/or prevalence are unknown. Fluoroquinolone monotherapy as standard therapy for common ocular infections needs to be reassessed. Ophthalmologists must become proactive and join the crusade to develop practical and prudent strategies for the administration of topical antibiotics.
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Affiliation(s)
- Darlene Miller
- Research Associate Professor, Department of Ophthalmology, Department of Microbiology and Immunology, Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
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Rolo J, Worning P, Boye Nielsen J, Sobral R, Bowden R, Bouchami O, Damborg P, Guardabassi L, Perreten V, Westh H, Tomasz A, de Lencastre H, Miragaia M. Evidence for the evolutionary steps leading to mecA-mediated β-lactam resistance in staphylococci. PLoS Genet 2017; 13:e1006674. [PMID: 28394942 PMCID: PMC5402963 DOI: 10.1371/journal.pgen.1006674] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 04/24/2017] [Accepted: 03/07/2017] [Indexed: 12/11/2022] Open
Abstract
The epidemiologically most important mechanism of antibiotic resistance in Staphylococcus aureus is associated with mecA–an acquired gene encoding an extra penicillin-binding protein (PBP2a) with low affinity to virtually all β-lactams. The introduction of mecA into the S. aureus chromosome has led to the emergence of methicillin-resistant S. aureus (MRSA) pandemics, responsible for high rates of mortality worldwide. Nonetheless, little is known regarding the origin and evolution of mecA. Different mecA homologues have been identified in species belonging to the Staphylococcus sciuri group representing the most primitive staphylococci. In this study we aimed to identify evolutionary steps linking these mecA precursors to the β-lactam resistance gene mecA and the resistance phenotype. We sequenced genomes of 106 S. sciuri, S. vitulinus and S. fleurettii strains and determined their oxacillin susceptibility profiles. Single-nucleotide polymorphism (SNP) analysis of the core genome was performed to assess the genetic relatedness of the isolates. Phylogenetic analysis of the mecA gene homologues and promoters was achieved through nucleotide/amino acid sequence alignments and mutation rates were estimated using a Bayesian analysis. Furthermore, the predicted structure of mecA homologue-encoded PBPs of oxacillin-susceptible and -resistant strains were compared. We showed for the first time that oxacillin resistance in the S. sciuri group has emerged multiple times and by a variety of different mechanisms. Development of resistance occurred through several steps including structural diversification of the non-binding domain of native PBPs; changes in the promoters of mecA homologues; acquisition of SCCmec and adaptation of the bacterial genetic background. Moreover, our results suggest that it was exposure to β-lactams in human-created environments that has driven evolution of native PBPs towards a resistance determinant. The evolution of β-lactam resistance in staphylococci highlights the numerous resources available to bacteria to adapt to the selective pressure of antibiotics. The emergence and rise of mecA-mediated β-lactam resistance in staphylococci has been one of the greatest concerns of the scientific and medical communities worldwide. However, little is known regarding the origin of the mecA gene determinant. In this study we demonstrate that antibiotic pressure in the human environment and in food additives used in livestock was the major driving force of the evolution and spread of resistance to β-lactams. Furthermore, we confirm the previous findings suggesting that the development of resistance occurs in primitive species of staphylococci through diversification of a native penicillin binding protein involved in cell wall synthesis. We also demonstrate that resistance was achieved through four distinct mechanisms: accumulation of substitutions in a specific domain of the protein; diversification of the promoter of the gene; acquisition of SCCmec, and adaptation of the genetic background. Our results highlight the resources that primitive bacteria used to thrive in a changing environment that has led to the methicillin-resistant Staphylococcus aureus (MRSA) pandemics.
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Affiliation(s)
- Joana Rolo
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
| | - Peder Worning
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
| | - Jesper Boye Nielsen
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
| | - Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Rory Bowden
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Ons Bouchami
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
| | - Peter Damborg
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Luca Guardabassi
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St Kitts, West Indies
| | - Vincent Perreten
- Department of Molecular Epidemiology and Infectious Diseases, Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Henrik Westh
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Tomasz
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, United States of America
| | - Hermínia de Lencastre
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, United States of America
| | - Maria Miragaia
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
- * E-mail:
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53
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Lee SH, Wang H, Labroli M, Koseoglu S, Zuck P, Mayhood T, Gill C, Mann P, Sher X, Ha S, Yang SW, Mandal M, Yang C, Liang L, Tan Z, Tawa P, Hou Y, Kuvelkar R, DeVito K, Wen X, Xiao J, Batchlett M, Balibar CJ, Liu J, Xiao J, Murgolo N, Garlisi CG, Sheth PR, Flattery A, Su J, Tan C, Roemer T. TarO-specific inhibitors of wall teichoic acid biosynthesis restore β-lactam efficacy against methicillin-resistant staphylococci. Sci Transl Med 2016; 8:329ra32. [PMID: 26962156 DOI: 10.1126/scitranslmed.aad7364] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The widespread emergence of methicillin-resistant Staphylococcus aureus (MRSA) has dramatically eroded the efficacy of current β-lactam antibiotics and created an urgent need for new treatment options. We report an S. aureus phenotypic screening strategy involving chemical suppression of the growth inhibitory consequences of depleting late-stage wall teichoic acid biosynthesis. This enabled us to identify early-stage pathway-specific inhibitors of wall teichoic acid biosynthesis predicted to be chemically synergistic with β-lactams. We demonstrated by genetic and biochemical means that each of the new chemical series discovered, herein named tarocin A and tarocin B, inhibited the first step in wall teichoic acid biosynthesis (TarO). Tarocins do not have intrinsic bioactivity but rather demonstrated potent bactericidal synergy in combination with broad-spectrum β-lactam antibiotics against diverse clinical isolates of methicillin-resistant staphylococci as well as robust efficacy in a murine infection model of MRSA. Tarocins and other inhibitors of wall teichoic acid biosynthesis may provide a rational strategy to develop Gram-positive bactericidal β-lactam combination agents active against methicillin-resistant staphylococci.
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Affiliation(s)
- Sang Ho Lee
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Hao Wang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Marc Labroli
- Merck Research Laboratories, West Point, PA 19486, USA
| | | | - Paul Zuck
- Merck Research Laboratories, West Point, PA 19486, USA
| | - Todd Mayhood
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Charles Gill
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Paul Mann
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Xinwei Sher
- Merck Research Laboratories, Boston, MA 02115, USA
| | - Sookhee Ha
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Shu-Wei Yang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Mihir Mandal
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | - Lianzhu Liang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Zheng Tan
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Paul Tawa
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Yan Hou
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Xiujuan Wen
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jing Xiao
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Jenny Liu
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jianying Xiao
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Payal R Sheth
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Amy Flattery
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jing Su
- Merck Research Laboratories, Kenilworth, NJ 07033, USA.
| | | | - Terry Roemer
- Merck Research Laboratories, Kenilworth, NJ 07033, USA.
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54
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Hasan N, Guo Z, Wu HF. Large protein analysis of Staphylococcus aureus and Escherichia coli by MALDI TOF mass spectrometry using amoxicillin functionalized magnetic nanoparticles. Anal Bioanal Chem 2016; 408:6269-81. [PMID: 27565791 DOI: 10.1007/s00216-016-9730-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 05/29/2016] [Accepted: 06/20/2016] [Indexed: 11/26/2022]
Abstract
Bacteria or their protein and peptide entity enrichment using biomolecules-functionalized magnetic nanoparticles, and analysis by matrix assisted laser desorption/ionization mass spectrometry (MALDI MS) is a promising technique to analyze microorganisms. High and low molecular weight proteins like penicillin-binding proteins are responsible for final step synthesis of peptidoglycan biosynthesis; those are the target of lactam antibiotics. In this paper, we synthesized magnetic nanoparticles (mag-NPs) and further modified them with 3-aminopropyltriethoxysilane, and then the β-lactam antibiotic amoxicillin was covalently linked to their surface. β-Lactam group attributes as penicillin binding proteins (PBPs) in bacteria. Staphylococcus aureus and Escherichia coli were used as model bacteria for enrichment based on the β-lactam affinity of magnetic nanoparticles, and then the bacteria were easily separated by an external magnet. Several high molecular weight penicillin binding proteins (PBPs) were detected by MALDI MS containing 10(4) and 10(3) colony-forming unit (cfu) per milileter (mL) of S. aureus and E. coli, respectively. In the case of E. coli, higher molecular weight PBPs were observed at 20 to 55 kDa in MALDI mass spectra. However, S. aureus bacteria resulted with femAB operon-based proteins, with molecular weight of 49570.4 Da, by MALDI MS after using amoxicillin functionalized-mag-NPs. The current approach provides an effective bacteria detection and preconcentration method that has high potential in the near future for fast and sensitive diagnosis of pathogenic bacteria infection. Graphical Abstract Schematic for large proteins analysis by MALDI TOF MS (a) mag-NPs and bacterial interaction (b) Penicillin binding proteins trapping by Amox-mag-NPs.
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Affiliation(s)
- Nazim Hasan
- Department of Chemistry and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, 70, Lien-Hai Road, Kaohsiung, 80424, Taiwan
- Department of Chemistry, Faculty of Science, Jazan University, P.O. Box 2097, Jazan, 82621, Saudi Arabia
| | - Zhongxian Guo
- Water Quality Office, Public Utilities Board, 82 Toh Guan Road East, Water Hub, # C4-03, Singapore, 608576, Singapore
| | - Hui-Fen Wu
- Department of Chemistry and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, 70, Lien-Hai Road, Kaohsiung, 80424, Taiwan.
- School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 807, Taiwan.
- Institute of Medical Science and Technology, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung, 80424, Taiwan.
- Marine Biotechnology, National Sun Yat-Sen University and Academia Sinica, Kaohsiung, 80424, Taiwan.
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55
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Chellat MF, Raguž L, Riedl R. Targeting Antibiotic Resistance. Angew Chem Int Ed Engl 2016; 55:6600-26. [PMID: 27000559 PMCID: PMC5071768 DOI: 10.1002/anie.201506818] [Citation(s) in RCA: 280] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/10/2015] [Indexed: 12/11/2022]
Abstract
Finding strategies against the development of antibiotic resistance is a major global challenge for the life sciences community and for public health. The past decades have seen a dramatic worldwide increase in human-pathogenic bacteria that are resistant to one or multiple antibiotics. More and more infections caused by resistant microorganisms fail to respond to conventional treatment, and in some cases, even last-resort antibiotics have lost their power. In addition, industry pipelines for the development of novel antibiotics have run dry over the past decades. A recent world health day by the World Health Organization titled "Combat drug resistance: no action today means no cure tomorrow" triggered an increase in research activity, and several promising strategies have been developed to restore treatment options against infections by resistant bacterial pathogens.
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Affiliation(s)
- Mathieu F Chellat
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Luka Raguž
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Rainer Riedl
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland.
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56
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Filippova EV, Kieser KJ, Luan CH, Wawrzak Z, Kiryukhina O, Rubin EJ, Anderson WF. Crystal structures of the transpeptidase domain of the Mycobacterium tuberculosis penicillin-binding protein PonA1 reveal potential mechanisms of antibiotic resistance. FEBS J 2016; 283:2206-18. [PMID: 27101811 PMCID: PMC5245116 DOI: 10.1111/febs.13738] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/30/2016] [Accepted: 04/15/2016] [Indexed: 01/21/2023]
Abstract
UNLABELLED Mycobacterium tuberculosis is a human respiratory pathogen that causes the deadly disease tuberculosis. The rapid global spread of antibiotic-resistant M. tuberculosis makes tuberculosis infections difficult to treat. To overcome this problem new effective antimicrobial strategies are urgently needed. One promising target for new therapeutic approaches is PonA1, a class A penicillin-binding protein, which is required for maintaining physiological cell wall synthesis and cell shape during growth in mycobacteria. Here, crystal structures of the transpeptidase domain, the enzymatic domain responsible for penicillin binding, of PonA1 from M. tuberculosis in the inhibitor-free form and in complex with penicillin V are reported. We used site-directed mutagenesis, antibiotic profiling experiments, and fluorescence thermal shift assays to measure PonA1's sensitivity to different classes of β-lactams. Structural comparison of the PonA1 apo-form and the antibiotic-bound form shows that binding of penicillin V induces conformational changes in the position of the loop β4'-α3 surrounding the penicillin-binding site. We have also found that binding of different antibiotics including penicillin V positively impacts protein stability, while other tested β-lactams such as clavulanate or meropenem resulted in destabilization of PonA1. Our antibiotic profiling experiments indicate that the transpeptidase activity of PonA1 in both M. tuberculosis and M. smegmatis mediates tolerance to specific cell wall-targeting antibiotics, particularly to penicillin V and meropenem. Because M. tuberculosis is an important human pathogen, these structural data provide a template to design novel transpeptidase inhibitors to treat tuberculosis infections. DATABASE Structural data are available in the PDB database under the accession numbers 5CRF and 5CXW.
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Affiliation(s)
- Ekaterina V Filippova
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Midwest Center for Structural Genomics (MCSG), Biosciences Division, Argonne National Laboratory, Argonne, IL, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Karen J Kieser
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Chi-Hao Luan
- Midwest Center for Structural Genomics (MCSG), Biosciences Division, Argonne National Laboratory, Argonne, IL, USA
- High Throughput Analysis Laboratory and Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Zdzislaw Wawrzak
- Life Science Collaborative Access Team, Synchrotron Research Center, Northwestern University, Evanston, IL, USA
| | - Olga Kiryukhina
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Midwest Center for Structural Genomics (MCSG), Biosciences Division, Argonne National Laboratory, Argonne, IL, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Eric J Rubin
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Wayne F Anderson
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Midwest Center for Structural Genomics (MCSG), Biosciences Division, Argonne National Laboratory, Argonne, IL, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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Foxley MA, Friedline AW, Jensen JM, Nimmo SL, Scull EM, King JB, Strange S, Xiao MT, Smith BE, Thomas Iii KJ, Glatzhofer DT, Cichewicz RH, Rice CV. Efficacy of ampicillin against methicillin-resistant Staphylococcus aureus restored through synergy with branched poly(ethylenimine). J Antibiot (Tokyo) 2016; 69:871-878. [PMID: 27189119 PMCID: PMC5115998 DOI: 10.1038/ja.2016.44] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/22/2016] [Accepted: 03/29/2016] [Indexed: 01/20/2023]
Abstract
Beta-lactam antibiotics kill Staphylococcus aureus bacteria by inhibiting the function of cell-wall penicillin binding proteins (PBPs) 1 and 3. However, β-lactams are ineffective against PBP2a, used by methicillin-resistant Staphylococcus aureus (MRSA) to perform essential cell wall crosslinking functions. PBP2a requires teichoic acid to properly locate and orient the enzyme, and thus MRSA is susceptible to antibiotics that prevent teichoic acid synthesis in the bacterial cytoplasm. As an alternative, we have used branched poly(ethylenimine), BPEI, to target teichoic acid in the bacterial cell wall. The result is restoration of MRSA susceptibility to the β-lactam antibiotic ampicillin with a MIC of 1 μg/mL, superior to that of vancomycin (MIC = 3.7 μg/mL). A checkerboard assay shows synergy of BPEI and ampicillin. Nuclear magnetic resonance (NMR) data show that BPEI alters the teichoic acid chemical environment. Laser scanning confocal microscopy (LSCM) images show BPEI residing on the bacterial cell wall where teichoic acids and PBPs are located.
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Affiliation(s)
- Melissa A Foxley
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Anthony W Friedline
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Jessica M Jensen
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Susan L Nimmo
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Erin M Scull
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Jarrod B King
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Stoffel Strange
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Min T Xiao
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Benjamin E Smith
- Samuel Roberts Noble Microscopy Laboratory, University of Oklahoma, Norman, OK, USA
| | - Kieth J Thomas Iii
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Daniel T Glatzhofer
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Robert H Cichewicz
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
| | - Charles V Rice
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, USA
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Affiliation(s)
- Mathieu F. Chellat
- Institut für Chemie und Biotechnologie, FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Luka Raguž
- Institut für Chemie und Biotechnologie, FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Rainer Riedl
- Institut für Chemie und Biotechnologie, FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
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da Silva RA, Liberio SA, do Amaral FMM, do Nascimento FRF, Torres LMB, Neto VM, Guerra RNM. Antimicrobial and Antioxidant Activity of <i>Anacardium occidentale</i> L. Flowers in Comparison to Bark and Leaves Extracts. ACTA ACUST UNITED AC 2016. [DOI: 10.4236/jbm.2016.44012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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60
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References. Antibiotics (Basel) 2015. [DOI: 10.1128/9781555819316.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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61
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Stieber B, Monecke S, Müller E, Büchler J, Ehricht R. Direct, Specific and Rapid Detection of Staphylococcal Proteins and Exotoxins Using a Multiplex Antibody Microarray. PLoS One 2015; 10:e0143246. [PMID: 26624622 PMCID: PMC4666605 DOI: 10.1371/journal.pone.0143246] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/02/2015] [Indexed: 12/12/2022] Open
Abstract
Background S. aureus is a pathogen in humans and animals that harbors a wide variety of virulence factors and resistance genes. This bacterium can cause a wide range of mild to life-threatening diseases. In the latter case, fast diagnostic procedures are important. In routine diagnostic laboratories, several genotypic and phenotypic methods are available to identify S. aureus strains and determine their resistances. However, there is a demand for multiplex routine diagnostic tests to directly detect staphylococcal toxins and proteins. Methods In this study, an antibody microarray based assay was established and validated for the rapid detection of staphylococcal markers and exotoxins. The following targets were included: staphylococcal protein A, penicillin binding protein 2a, alpha- and beta-hemolysins, Panton Valentine leukocidin, toxic shock syndrome toxin, enterotoxins A and B as well as staphylokinase. All were detected simultaneously within a single experiment, starting from a clonal culture on standard media. The detection of bound proteins was performed using a new fluorescence reading device for microarrays. Results 110 reference strains and clinical isolates were analyzed using this assay, with a DNA microarray for genotypic characterization performed in parallel. The results showed a general high concordance of genotypic and phenotypic data. However, genotypic analysis found the hla gene present in all S. aureus isolates but its expression under given conditions depended on the clonal complex affiliation of the actual isolate. Conclusions The multiplex antibody assay described herein allowed a rapid and reliable detection of clinically relevant staphylococcal toxins as well as resistance- and species-specific markers.
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Affiliation(s)
- Bettina Stieber
- Alere Technologies GmbH, Jena, Germany
- Institute for Medical Microbiology and Hygiene, Technische Universität Dresden, Dresden, Germany
- Infectognostics Forschungscampus Jena, Jena, Germany
- * E-mail:
| | - Stefan Monecke
- Alere Technologies GmbH, Jena, Germany
- Institute for Medical Microbiology and Hygiene, Technische Universität Dresden, Dresden, Germany
- Infectognostics Forschungscampus Jena, Jena, Germany
| | - Elke Müller
- Alere Technologies GmbH, Jena, Germany
- Infectognostics Forschungscampus Jena, Jena, Germany
| | - Joseph Büchler
- Alere San Diego, Inc., San Diego, California, United States of America
| | - Ralf Ehricht
- Alere Technologies GmbH, Jena, Germany
- Infectognostics Forschungscampus Jena, Jena, Germany
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Zeng X, Gillespie B, Lin J. Important Role of a Putative Lytic Transglycosylase Cj0843c in β-Lactam Resistance in Campylobacter jejuni. Front Microbiol 2015; 6:1292. [PMID: 26635760 PMCID: PMC4647113 DOI: 10.3389/fmicb.2015.01292] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 11/04/2015] [Indexed: 01/26/2023] Open
Abstract
Beta-lactam antibiotics are an important class of antibiotics for treating bacterial infections. Despite prevalent β-lactam resistance in Campylobacter jejuni, the leading bacterial cause of human diarrhea in developed countries, molecular mechanism of β-lactam resistance in C. jejuni is still largely unknown. In this study, C. jejuni 81–176 was used for random transposon mutagenesis. Screening of a 2,800-mutant library identified 22 mutants with increased susceptibility to ampicillin. Of these mutants, two mutants contains mutations in Cj0843c (a putative lytic transglycosylase gene) and in its upstream gene Cj0844c, respectively. Complementation experiment demonstrated that the Cj0843 contributes to β-lactam resistance. The Cj0843c insertional mutation was subsequently introduced to diverse C. jejuni clinical strains for MIC test, showing that Cj0843c contributes to both intrinsic and acquired β-lactam resistance of C. jejuni. Consistent with this finding, inactivation of Cj0843c also dramatically reduced β-lactamase activity. Genomic examination and PCR analysis showed Cj0843c is widely distributed in C. jejuni. High purity recombinant Cj0843c was produced for generation of specific antiserum. The Cj0843 was localized in the periplasm, as demonstrated by immunoblotting using specific antibodies. Turbidimetric assay further demonstrated the capability of the purified Cj0843c to hydrolyze cell walls. Inactivation of Cj0843c also significantly reduced C. jejuni colonization in the intestine. Together, this study identifies a mechanism of β-lactam resistance in C. jejuni and provides insights into the role of cell wall metabolism in regulating β-lactamase activity.
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Affiliation(s)
- Ximin Zeng
- Department of Animal Science, The University of Tennessee, Knoxville TN, USA
| | - Barbara Gillespie
- Department of Animal Science, The University of Tennessee, Knoxville TN, USA
| | - Jun Lin
- Department of Animal Science, The University of Tennessee, Knoxville TN, USA
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63
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Goh S, Loeffler A, Lloyd DH, Nair SP, Good L. Oxacillin sensitization of methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius by antisense peptide nucleic acids in vitro. BMC Microbiol 2015; 15:262. [PMID: 26560174 PMCID: PMC4642645 DOI: 10.1186/s12866-015-0599-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 11/05/2015] [Indexed: 01/29/2023] Open
Abstract
Background Antibiotic resistance genes can be targeted by antisense agents, which can reduce their expression and thus restore cellular susceptibility to existing antibiotics. Antisense inhibitors can be gene and pathogen specific, or designed to inhibit a group of bacteria having conserved sequences within resistance genes. Here, we aimed to develop antisense peptide nucleic acids (PNAs) that could be used to effectively restore susceptibility to β-lactams in methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP). Results Antisense PNAs specific for conserved regions of the mobilisable gene mecA, and the growth essential gene, ftsZ, were designed. Clinical MRSA and MRSP strains of high oxacillin resistance were treated with PNAs and assayed for reduction in colony forming units on oxacillin plates, reduction in target gene mRNA levels, and cell size. Anti-mecA PNA at 7.5 and 2.5 μM reduced mecA mRNA in MRSA and MRSP (p < 0.05). At these PNA concentrations, 66 % of MRSA and 92 % of MRSP cells were killed by oxacillin (p < 0.01). Anti-ftsZ PNA at 7.5 and 2.5 μM reduced ftsZ mRNA in MRSA and MRSP, respectively (p ≤ 0.05). At these PNA concentrations, 86 % of MRSA cells and 95 % of MRSP cells were killed by oxacillin (p < 0.05). Anti-ftsZ PNAs resulted in swelling of bacterial cells. Scrambled PNA controls did not affect MRSA but sensitized MRSP moderately to oxacillin without affecting mRNA levels. Conclusions The antisense PNAs effects observed provide in vitro proof of concept that this approach can be used to reverse β-lactam resistance in staphylococci. Further studies are warranted as clinical treatment alternatives are needed. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0599-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shan Goh
- Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, UK.
| | - Anette Loeffler
- Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, UK
| | - David H Lloyd
- Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, UK
| | - Sean P Nair
- Department of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK
| | - Liam Good
- Pathology and Pathogen Biology, Royal Veterinary College, Royal College Street, London, UK
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Teo ACK, Roper DI. Core Steps of Membrane-Bound Peptidoglycan Biosynthesis: Recent Advances, Insight and Opportunities. Antibiotics (Basel) 2015; 4:495-520. [PMID: 27025638 PMCID: PMC4790310 DOI: 10.3390/antibiotics4040495] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/03/2015] [Accepted: 10/26/2015] [Indexed: 11/16/2022] Open
Abstract
We are entering an era where the efficacy of current antibiotics is declining, due to the development and widespread dispersion of antibiotic resistance mechanisms. These factors highlight the need for novel antimicrobial discovery. A large number of antimicrobial natural products elicit their effect by directly targeting discrete areas of peptidoglycan metabolism. Many such natural products bind directly to the essential cell wall precursor Lipid II and its metabolites, i.e., preventing the utlisation of vital substrates by direct binding rather than inhibiting the metabolising enzymes themselves. Concurrently, there has been an increase in the knowledge surrounding the proteins essential to the metabolism of Lipid II at and across the cytoplasmic membrane. In this review, we draw these elements together and look to future antimicrobial opportunities in this area.
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Affiliation(s)
- Alvin C K Teo
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
| | - David I Roper
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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65
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Gonzales PR, Pesesky MW, Bouley R, Ballard A, Biddy BA, Suckow MA, Wolter WR, Schroeder VA, Burnham CAD, Mobashery S, Chang M, Dantas G. Synergistic, collaterally sensitive β-lactam combinations suppress resistance in MRSA. Nat Chem Biol 2015; 11:855-61. [PMID: 26368589 PMCID: PMC4618095 DOI: 10.1038/nchembio.1911] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 08/17/2015] [Indexed: 12/21/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent multidrug-resistant pathogens worldwide, exhibiting increasing resistance to the latest antibiotic therapies. Here we show that the triple β-lactam combination meropenem-piperacillin-tazobactam (ME/PI/TZ) acts synergistically and is bactericidal against MRSA subspecies N315 and 72 other clinical MRSA isolates in vitro and clears MRSA N315 infection in a mouse model. ME/PI/TZ suppresses evolution of resistance in MRSA via reciprocal collateral sensitivity of its constituents. We demonstrate that these activities also extend to other carbapenem-penicillin-β-lactamase inhibitor combinations. ME/PI/TZ circumvents the tight regulation of the mec and bla operons in MRSA, the basis for inducible resistance to β-lactam antibiotics. Furthermore, ME/PI/TZ subverts the function of penicillin-binding protein-2a (PBP2a) via allostery, which we propose as the mechanism for both synergy and collateral sensitivity. Showing in vivo activity similar to that of linezolid, ME/PI/TZ demonstrates that combinations of older β-lactam antibiotics could be effective against MRSA infections in humans.
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Affiliation(s)
- Patrick R. Gonzales
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Mitchell W. Pesesky
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Renee Bouley
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Anna Ballard
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Brent A. Biddy
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Mark A. Suckow
- Freimann Life Sciences Center and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - William R. Wolter
- Freimann Life Sciences Center and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Valerie A. Schroeder
- Freimann Life Sciences Center and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Carey-Ann D. Burnham
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Gautam Dantas
- Center for Genome Sciences & Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
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Diaz R, Ramalheira E, Afreixo V, Gago B. Methicillin-resistant Staphylococcus aureus carrying the new mecC gene--a meta-analysis. Diagn Microbiol Infect Dis 2015; 84:135-40. [PMID: 26652130 DOI: 10.1016/j.diagmicrobio.2015.10.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/10/2015] [Accepted: 10/19/2015] [Indexed: 12/25/2022]
Abstract
In 2011, a new mecA gene homolog, named mecC gene, was found in isolates from both humans and animals. The discovery of methicillin-resistant Staphylococcus aureus (MRSA) carrying the mecC gene has caused speculations about the origin, epidemiology, and impact of these isolates. The objective of this work is to perform a meta-analysis on the prevalence of mecC MRSA, based on previously published results. Meta-analysis showed that the overall pooled prevalence is 0.009% (95% confidence interval=0.05-0.013) and that there was evidence of heterogeneity (P<0.01, I(2)=97%). In conclusion, the very low reported prevalence provides an important baseline to monitor the epidemiology of this emerging form of MRSA.
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Affiliation(s)
- Raquel Diaz
- Health Sciences Department, University of Aveiro, Institute for Research in Biomedicine-iBiMED, Health Sciences Program, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Elmano Ramalheira
- Health Sciences Department, University of Aveiro, Department of Medical Microbiology, Centro Hospitalar Baixo Vouga, Av. Artur Ravara, 3814-501, Aveiro, Portugal.
| | - Vera Afreixo
- Department of Mathematics, University of Aveiro, Institute for Biomedicine-iBiMED, Health Sciences Program, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Bruno Gago
- Health Sciences Department, University of Aveiro, Institute for Biomedicine-iBiMED, Health Sciences Program, University of Aveiro, 3810-193 Aveiro, Portugal.
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Yao Z, Peng Y, Chen X, Bi J, Li Y, Ye X, Shi J. Healthcare Associated Infections of Methicillin-Resistant Staphylococcus aureus: A Case-Control-Control Study. PLoS One 2015; 10:e0140604. [PMID: 26470023 PMCID: PMC4607165 DOI: 10.1371/journal.pone.0140604] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 09/27/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most widespread and dangerous pathogens in healthcare settings. We carried out this case-control-control study at a tertiary care hospital in Guangzhou, China, to examine the antimicrobial susceptibility patterns, risk factors and clinical outcomes of MRSA infections. METHODS A total of 57 MRSA patients, 116 methicillin-susceptible Staphylococcus aureus (MSSA) patients and 102 S. aureus negative patients were included in this study. We applied the disk diffusion method to compare the antimicrobial susceptibilities of 18 antibiotics between MRSA and MSSA isolates. Risk factors of MRSA infections were evaluated using univariate and multivariate logistic regression models. We used Cox proportional hazards models and logistic regression analysis to assess the hospital stay duration and fatality for patients with MRSA infections. RESULTS The MRSA group had significantly higher resistance rates for most drugs tested compared with the MSSA group. Using MSSA patients as controls, the following independent risk factors of MRSA infections were identified: 3 or more prior hospitalizations (OR 2.8, 95% CI 1.3-5.8, P = 0.007), chronic obstructive pulmonary disease (OR 5.9, 95% CI 1.7-20.7, P = 0.006), and use of a respirator (OR 3.6, 95% CI 1.0-12.9, P = 0.046). With the S. aureus negative patients as controls, use of a respirator (OR 3.8, 95% CI 1.0-13.9, P = 0.047) and tracheal intubation (OR 8.2, 95% CI 1.5-45.1, P = 0.016) were significant risk factors for MRSA infections. MRSA patients had a longer hospital stay duration and higher fatality in comparison with those in the two control groups. CONCLUSIONS MRSA infections substantially increase hospital stay duration and fatality. Thus, MRSA infections are serious issues in this healthcare setting and should receive more attention from clinicians.
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Affiliation(s)
- Zhenjiang Yao
- Department of Epidemiology and Health Statistics, Guangdong Pharmaceutical University, Guangzhou, China
- * E-mail:
| | - Yang Peng
- Department of Epidemiology and Health Statistics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Xiaofeng Chen
- Division of Infectious Diseases, The People’s Hospital of Meizhou, Meizhou, China
| | - Jiaqi Bi
- Department of Environmental and School Health, Shajing Health Inspection Institute, Shenzhen, China
| | - Ying Li
- Division of Environmental Health, Public Health Laboratory Center, Guangdong Pharmaceutical University, Guangzhou, China
| | - Xiaohua Ye
- Department of Epidemiology and Health Statistics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Jing Shi
- Department of Preventive Medicine, Hebei University of Chinese Medicine, Shijiazhuang, China
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Stefani S, Campanile F, Santagati M, Mezzatesta ML, Cafiso V, Pacini G. Insights and clinical perspectives of daptomycin resistance in Staphylococcus aureus: A review of the available evidence. Int J Antimicrob Agents 2015; 46:278-89. [DOI: 10.1016/j.ijantimicag.2015.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 02/04/2023]
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Akindolire MA, Babalola OO, Ateba CN. Detection of Antibiotic Resistant Staphylococcus aureus from Milk: A Public Health Implication. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 12:10254-75. [PMID: 26308035 PMCID: PMC4586610 DOI: 10.3390/ijerph120910254] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/13/2015] [Accepted: 08/15/2015] [Indexed: 11/16/2022]
Abstract
The aim of this study was to investigate the occurrence, antibiotic susceptibility profiles, and virulence genes determinants of S. aureus isolated from milk obtained from retail outlets of the North-West Province, South Africa. To achieve this, 200 samples of raw, bulk and pasteurised milk were obtained randomly from supermarkets, shops and some farms in the North-West Province between May 2012 and April 2013. S. aureus was isolated and positively identified using morphological (Gram staining), biochemical (DNase, catalase, haemolysis and rapid slide agglutination) tests, protein profile analysis (MALDI-TOF mass spectrometry) and molecular (nuc specific PCR) methods. The antimicrobial resistance profiles of the isolates were determined using the phenotypic agar diffusion method. Genes encoding enterotoxins, exfoliative toxins and collagen adhesins were also screened using PCR. Among all the samples examined, 30 of 40 raw milk samples (75%), 25 of 85 bulk milk samples (29%) and 10 of 75 pasteurised milk samples (13%) were positive for S. aureus. One hundred and fifty-six PCR-confirmed S. aureus isolates were obtained from 75 contaminated milk samples. A large proportion (60%-100%) of the isolates was resistant to penicillin G, ampicillin, oxacillin, vancomycin, teicoplanin and erythromycin. On the contrary, low level resistance (8.3%-40%) was observed for gentamicin, kanamycin and sulphamethoxazole. Methicillin resistance was detected in 59% of the multidrug resistant isolates and this was a cause for concern. However, only a small proportion (20.6%) of these isolates possessed PBP2a which codes for Methicillin resistance in S. aureus. In addition, 32.7% of isolates possessed the sec gene whereas the sea, seb sed, see, cna, eta, etb genes were not detected. The findings of this study showed that raw, bulk and pasteurised milk in the North-West Province is contaminated with toxigenic and multi-drug resistant S. aureus strains. There is a need to implement appropriate control measures to reduce contamination as well as the spread of virulent S. aureus strains and the burden of disease in humans.
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Affiliation(s)
- Muyiwa Ajoke Akindolire
- Department of Biological Sciences, School of Environmental and Health Sciences, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, Mafikeng Campus, South Africa.
| | - Olubukola Oluranti Babalola
- Department of Biological Sciences, School of Environmental and Health Sciences, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, Mafikeng Campus, South Africa.
- Food Security and Safety Niche Area, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, Mafikeng 2735, South Africa.
| | - Collins Njie Ateba
- Department of Biological Sciences, School of Environmental and Health Sciences, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, Mafikeng Campus, South Africa.
- Food Security and Safety Niche Area, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, Mafikeng 2735, South Africa.
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70
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Threat of multidrug resistant Staphylococcus aureus in Western Nepal. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2015. [DOI: 10.1016/s2222-1808(15)60900-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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71
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Santiago C, Pang EL, Lim KH, Loh HS, Ting KN. Inhibition of penicillin-binding protein 2a (PBP2a) in methicillin resistant Staphylococcus aureus (MRSA) by combination of ampicillin and a bioactive fraction from Duabanga grandiflora. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 15:178. [PMID: 26060128 PMCID: PMC4460762 DOI: 10.1186/s12906-015-0699-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 05/29/2015] [Indexed: 11/25/2022]
Abstract
Background The inhibition of penicillin-binding protein 2a (PBP2a) is a promising solution in overcoming resistance of methicillin resistance Staphylococcus aureus (MRSA). A potential approach in achieving this is by combining natural product with currently available antibiotics to restore the activity as well as to amplify the therapeutic ability of the drugs. We studied inhibition effects of a bioactive fraction, F-10 (isolated from the leaves of Duabanga grandiflora) alone and in combination with a beta-lactam drug, ampicillin on MRSA growth and expression of PBP2a. Additionally, phytochemical analysis was conducted on F-10 to identify the classes of phytochemicals present. Methods Fractionation of the ethyl acetate leaf extract was achieved by successive column chromatography which eventually led to isolation of an active fraction, F-10. Both extract and F-10 were analyzed for the presence of major classes of phytochemicals in addition to obtaining a high performance liquid chromatography (HPLC) profile to reveal the complexity of the fraction F-10. Broth microdilution method was employed to determine minimum inhibitory concentration (MIC) of the extract and fractions against MRSA. Evaluation of synergistic activity of the active fraction with ampicillin was determined using checkerboard methodand kinetic growth experiments. Effect of combination treatments on expression of PBP2a, a protein that confers resistance to beta-lactam antibiotics, was elucidated with the Western blot assay. Results MIC of F-10 against MRSA was 750 mg/L which showed an improved activity by 4-fold compared to its crude extract (MIC = 3000 mg/L). Phytochemical analysis revealed occurrence of tannins, saponin, flavonoids, sterols, and glycosides in F10 fraction. In FIC index interpretation, the most synergistic activity was achieved for combinations of 1/64 × MIC ampicillin + 1/4 × MIC F-10. The combination also evidently inhibited MRSA growth in kinetic growth curve assay. As a result of this synergistic interaction, MIC of ampicillin against MRSA was reduced to 0.78 mg/L (64-fold) from initial value of 50 mg/L. Western blot analysis suggested inhibition of PBP2a in MRSA cultures grown in synergistic combination treatment in which no PBP2a band was expressed. Conclusions The results demonstrated synergism between fraction F-10 of D. grandiflora with ampicillin in suppressing MRSA growth via PBP2a inhibition.
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Abstract
Staphylococcus aureus is a major human and veterinary pathogen worldwide. Methicillin-resistant S. aureus (MRSA) poses a significant and enduring problem to the treatment of infection by such strains. Resistance is usually conferred by the acquisition of a nonnative gene encoding a penicillin-binding protein (PBP2a), with significantly lower affinity for β-lactams. This resistance allows cell-wall biosynthesis, the target of β-lactams, to continue even in the presence of typically inhibitory concentrations of antibiotic. PBP2a is encoded by the mecA gene, which is carried on a distinct mobile genetic element (SCCmec), the expression of which is controlled through a proteolytic signal transduction pathway comprising a sensor protein (MecR1) and a repressor (MecI). Many of the molecular and biochemical mechanisms underlying methicillin resistance in S. aureus have been elucidated, including regulatory events and the structure of key proteins. Here we review recent advances in this area.
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Affiliation(s)
- Sharon J. Peacock
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
| | - Gavin K. Paterson
- School of Biological, Biomedical, and Environmental Sciences, University of Hull, Hull HU6 7RX, United Kingdom
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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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Chan LC, Basuino L, Diep B, Hamilton S, Chatterjee SS, Chambers HF. Ceftobiprole- and ceftaroline-resistant methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2015; 59:2960-3. [PMID: 25753637 PMCID: PMC4394828 DOI: 10.1128/aac.05004-14] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/02/2015] [Indexed: 02/07/2023] Open
Abstract
The role of mecA mutations in conferring resistance to ceftobiprole and ceftaroline, cephalosporins with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity, was determined with MRSA strains COL and SF8300. The SF8300 ceftaroline-passaged mutant carried a single mecA mutation, E447K (E-to-K change at position 447), and expressed low-level resistance. This mutation in COL conferred high-level resistance to ceftobiprole but only low-level resistance to ceftaroline. The COL ceftaroline-passaged mutant, which expressed high-level resistance to ceftobiprole and ceftaroline, had mutations in pbp2, pbp4, and gdpP but not mecA.
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Affiliation(s)
- Liana C Chan
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Li Basuino
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA
| | - Binh Diep
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA
| | - Stephanie Hamilton
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA
| | - Som S Chatterjee
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA
| | - Henry F Chambers
- Division of Infectious Disease, Department of Medicine, San Francisco General Hospital, San Francisco, California, USA
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Abstract
Gram-positive organisms, including the pathogens Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, have dynamic cell envelopes that mediate interactions with the environment and serve as the first line of defense against toxic molecules. Major components of the cell envelope include peptidoglycan (PG), which is a well-established target for antibiotics, teichoic acids (TAs), capsular polysaccharides (CPS), surface proteins, and phospholipids. These components can undergo modification to promote pathogenesis, decrease susceptibility to antibiotics and host immune defenses, and enhance survival in hostile environments. This chapter will cover the structure, biosynthesis, and important functions of major cell envelope components in gram-positive bacteria. Possible targets for new antimicrobials will be noted.
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Meng J, He G, Wang H, Jia M, Ma X, Da F, Wang N, Hou Z, Xue X, Li M, Zhou Y, Luo X. Reversion of antibiotic resistance by inhibiting mecA in clinical methicillin-resistant Staphylococci by antisense phosphorothioate oligonucleotide. J Antibiot (Tokyo) 2014; 68:158-64. [PMID: 25269464 DOI: 10.1038/ja.2014.132] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/18/2014] [Accepted: 08/27/2014] [Indexed: 01/11/2023]
Abstract
Methicillin-resistant Staphylococci (MRS), methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) have become a challenging problem in nosocomial infections and are connected with high morbidity and mortality rates. This is due to the increasing incidence of resistance to virtually all β-lactams and a wide variety of antimicrobials. The spread of MRS severely limits therapeutic options and generates the need for novel antibiotics that are able to combat MRS infections. One method of inhibiting bacterial growth is by blocking the expression of conserved bacterial genes and provides potential new avenues for generating a new generation of antimicrobials. The mecA gene is highly conserved among Staphylococcal species, and this makes it an ideal target for antisense inhibition. We had identified a target sequence (854-871 nt) within the mecA mRNA coding region that is particularly sensitive to antisense inhibition. The anti-mecA PS-ODN04 oligonucleotide was encapsulated into an anionic liposome. MRSA01 and MRSE01 clinical strains treated with this antisense sequence became susceptible to existing β-lactam antibiotics, and their growth was inhibited by oxacillin in vitro and in vivo. PS-ODN04 reduced the bacterial titers in the blood of mice infected with MRSA01 and MRSE01 and significantly improved their survival rate. Our data offer a possible new strategy for treating MRS infections.
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Affiliation(s)
- Jingru Meng
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Gonghao He
- Department of Pharmacy, Kunming General Hospital of Chengdu Military Region, Kunming, China
| | - Hui Wang
- Jiuquan Satellite Launch Center, Jiuquan, China
| | - Min Jia
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Xue Ma
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Fei Da
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Ning Wang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Zheng Hou
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Xiaoyan Xue
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Mingkai Li
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Ying Zhou
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
| | - Xiaoxing Luo
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, China
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77
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Penicillin-binding proteins: evergreen drug targets. Curr Opin Pharmacol 2014; 18:112-9. [DOI: 10.1016/j.coph.2014.09.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 09/12/2014] [Indexed: 02/07/2023]
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78
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Mandal SS, Navratna V, Sharma P, Gopal B, Bhattacharyya AJ. Titania nanotube-modified screen printed carbon electrodes enhance the sensitivity in the electrochemical detection of proteins. Bioelectrochemistry 2014; 98:46-52. [DOI: 10.1016/j.bioelechem.2014.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/19/2014] [Accepted: 03/10/2014] [Indexed: 10/25/2022]
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79
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Fishovitz J, Rojas-Altuve A, Otero L, Dawley M, Carrasco-López C, Chang M, Hermoso JA, Mobashery S. Disruption of allosteric response as an unprecedented mechanism of resistance to antibiotics. J Am Chem Soc 2014; 136:9814-7. [PMID: 24955778 PMCID: PMC4210145 DOI: 10.1021/ja5030657] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Indexed: 02/07/2023]
Abstract
Ceftaroline, a recently approved β-lactam antibiotic for treatment of infections by methicillin-resistant Staphylococcus aureus (MRSA), is able to inhibit penicillin-binding protein 2a (PBP2a) by triggering an allosteric conformational change that leads to the opening of the active site. The opened active site is now vulnerable to inhibition by a second molecule of ceftaroline, an event that impairs cell-wall biosynthesis and leads to bacterial death. The triggering of the allosteric effect takes place by binding of the first antibiotic molecule 60 Å away from the active site of PBP2a within the core of the allosteric site. We document, by kinetic studies and by determination of three X-ray structures of the mutant variants of PBP2a that result in resistance to ceftaroline, that the effect of these clinical mutants is the disruption of the allosteric trigger in this important protein in MRSA. This is an unprecedented mechanism for antibiotic resistance.
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Affiliation(s)
- Jennifer Fishovitz
- Department
of Chemistry and Biochemistry, University
of Notre Dame, Nieuwland
Science Hall, Notre Dame, Indiana 46556, United
States
| | - Alzoray Rojas-Altuve
- Department
of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”,
CSIC, Serrano 119, 28006 Madrid, Spain
| | - Lisandro
H. Otero
- Department
of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”,
CSIC, Serrano 119, 28006 Madrid, Spain
| | - Matthew Dawley
- Department
of Chemistry and Biochemistry, University
of Notre Dame, Nieuwland
Science Hall, Notre Dame, Indiana 46556, United
States
| | - Cesar Carrasco-López
- Department
of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”,
CSIC, Serrano 119, 28006 Madrid, Spain
| | - Mayland Chang
- Department
of Chemistry and Biochemistry, University
of Notre Dame, Nieuwland
Science Hall, Notre Dame, Indiana 46556, United
States
| | - Juan A. Hermoso
- Department
of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”,
CSIC, Serrano 119, 28006 Madrid, Spain
| | - Shahriar Mobashery
- Department
of Chemistry and Biochemistry, University
of Notre Dame, Nieuwland
Science Hall, Notre Dame, Indiana 46556, United
States
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80
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Fishovitz J, Hermoso JA, Chang M, Mobashery S. Penicillin-binding protein 2a of methicillin-resistant Staphylococcus aureus. IUBMB Life 2014; 66:572-7. [PMID: 25044998 DOI: 10.1002/iub.1289] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/01/2014] [Indexed: 01/31/2023]
Abstract
High-level resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) is due to expression of penicillin-binding protein 2a (PBP2a), a transpeptidase that catalyzes cell-wall crosslinking in the face of the challenge by β-lactam antibiotics. The activity of this protein is regulated by allostery at a site 60 Å distant from the active site, where crosslinking of cell wall takes place. This review discusses the state of knowledge on this important enzyme of cell-wall biosynthesis in MRSA.
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Affiliation(s)
- Jennifer Fishovitz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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81
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Novel determinants of antibiotic resistance: identification of mutated loci in highly methicillin-resistant subpopulations of methicillin-resistant Staphylococcus aureus. mBio 2014; 5:e01000. [PMID: 24713324 PMCID: PMC3993859 DOI: 10.1128/mbio.01000-13] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We identified mutated genes in highly resistant subpopulations of methicillin-resistant Staphylococcus aureus (MRSA) that are most likely responsible for the historic failure of the β-lactam family of antibiotics as therapeutic agents against these important pathogens. Such subpopulations are produced during growth of most clinical MRSA strains, including the four historically early MRSA isolates studied here. Chromosomal DNA was prepared from the highly resistant cells along with DNA from the majority of cells (poorly resistant cells) followed by full genome sequencing. In the highly resistant cells, mutations were identified in 3 intergenic sequences and 27 genes representing a wide range of functional categories. A common feature of these mutations appears to be their capacity to induce high-level β-lactam resistance and increased amounts of the resistance protein PBP2A in the bacteria. The observations fit a recently described model in which the ultimate controlling factor of the phenotypic expression of β-lactam resistance in MRSA is a RelA-mediated stringent response. IMPORTANCE It has been well established that the level of antibiotic resistance (i.e., minimum concentration of a β-lactam antibiotic needed to inhibit growth) of a methicillin-resistant Staphylococcus aureus (MRSA) strain depends on the transcription and translation of the resistance protein PBP2A. Here we describe mutated loci in an additional novel set of genetic determinants that appear to be essential for the unusually high resistance levels typical of subpopulations of staphylococci that are produced with unique low frequency in most MRSA clinical isolates. We propose that mutations in these determinants can trigger induction of the stringent stress response which was recently shown to cause increased transcription/translation of the resistance protein PBP2A in parallel with the increased level of resistance.
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82
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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: 98] [Impact Index Per Article: 9.8] [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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83
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Skalweit Helfand M. β-lactams against emerging ‘superbugs’: progress and pitfalls. Expert Rev Clin Pharmacol 2014; 1:559-71. [DOI: 10.1586/17512433.1.4.559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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84
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Zeng X, Brown S, Gillespie B, Lin J. A single nucleotide in the promoter region modulates the expression of the -lactamase OXA-61 in Campylobacter jejuni. J Antimicrob Chemother 2014; 69:1215-23. [DOI: 10.1093/jac/dkt515] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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85
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Yang Y, Zhang Z, Li S, Ye X, Li X, He K. Synergy effects of herb extracts: Pharmacokinetics and pharmacodynamic basis. Fitoterapia 2014; 92:133-47. [DOI: 10.1016/j.fitote.2013.10.010] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 10/17/2013] [Accepted: 10/21/2013] [Indexed: 02/07/2023]
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86
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Harrison EM, Paterson GK, Holden MTG, Ba X, Rolo J, Morgan FJE, Pichon B, Kearns A, Zadoks RN, Peacock SJ, Parkhill J, Holmes MA. A novel hybrid SCCmec-mecC region in Staphylococcus sciuri. J Antimicrob Chemother 2013; 69:911-8. [PMID: 24302651 PMCID: PMC3956370 DOI: 10.1093/jac/dkt452] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Methicillin resistance in Staphylococcus spp. results from the expression of an alternative penicillin-binding protein 2a (encoded by mecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant of mecA known as mecC (formerly mecALGA251) was identified in Staphylococcus aureus isolates from both humans and animals. In this study, we identified two Staphylococcus sciuri subsp. carnaticus isolates from bovine infections that harbour three different mecA homologues: mecA, mecA1 and mecC. METHODS We subjected the two isolates to whole-genome sequencing to further understand the genetic context of the mec-containing region. We also used PCR and RT-PCR to investigate the excision and expression of the SCCmec element and mec genes, respectively. RESULTS Whole-genome sequencing revealed a novel hybrid SCCmec region at the orfX locus consisting of a class E mec complex (mecI-mecR1-mecC1-blaZ) located immediately downstream of a staphylococcal cassette chromosome mec (SCCmec) type VII element. A second SCCmec attL site (attL2), which was imperfect, was present downstream of the mecC region. PCR analysis of stationary-phase cultures showed that both the SCCmec type VII element and a hybrid SCCmec-mecC element were capable of excision from the genome and forming a circular intermediate. Transcriptional analysis showed that mecC and mecA, but not mecA1, were both expressed in liquid culture supplemented with oxacillin. CONCLUSIONS Overall, this study further highlights that a range of staphylococcal species harbour the mecC gene and furthers the view that coagulase-negative staphylococci associated with animals may act as reservoirs of antibiotic resistance genes for more pathogenic staphylococcal species.
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Affiliation(s)
- Ewan M Harrison
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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87
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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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88
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Ba X, Harrison EM, Edwards GF, Holden MTG, Larsen AR, Petersen A, Skov RL, Peacock SJ, Parkhill J, Paterson GK, Holmes MA. Novel mutations in penicillin-binding protein genes in clinical Staphylococcus aureus isolates that are methicillin resistant on susceptibility testing, but lack the mec gene. J Antimicrob Chemother 2013; 69:594-7. [PMID: 24216768 PMCID: PMC3922151 DOI: 10.1093/jac/dkt418] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Objectives Methicillin-resistant Staphylococcus aureus (MRSA) is an important global health problem. MRSA resistance to β-lactam antibiotics is mediated by the mecA or mecC genes, which encode an alternative penicillin-binding protein (PBP) 2a that has a low affinity to β-lactam antibiotics. Detection of mec genes or PBP2a is regarded as the gold standard for the diagnosis of MRSA. We identified four MRSA isolates that lacked mecA or mecC genes, but were still phenotypically resistant to pencillinase-resistant β-lactam antibiotics. Methods The four human S. aureus isolates were investigated by whole genome sequencing and a range of phenotypic assays. Results We identified a number of amino acid substitutions present in the endogenous PBPs 1, 2 and 3 that were found in the resistant isolates but were absent in closely related susceptible isolates and which may be the basis of resistance. Of particular interest are three identical amino acid substitutions in PBPs 1, 2 and 3, occurring independently in isolates from at least two separate multilocus sequence types. Two different non-conservative substitutions were also present in the same amino acid of PBP1 in two isolates from two different sequence types. Conclusions This work suggests that phenotypically resistant MRSA could be misdiagnosed using molecular methods alone and provides evidence of alternative mechanisms for β-lactam resistance in MRSA that may need to be considered by diagnostic laboratories.
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Affiliation(s)
- Xiaoliang Ba
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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89
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Lysozyme and penicillin inhibit the growth of anaerobic ammonium-oxidizing planctomycetes. Appl Environ Microbiol 2013; 79:7763-9. [PMID: 24096424 DOI: 10.1128/aem.02467-13] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Anaerobic ammonium-oxidizing (anammox) planctomycetes oxidize ammonium in the absence of molecular oxygen with nitrite as the electron acceptor. Although planctomycetes are generally assumed to lack peptidoglycan in their cell walls, recent genome data imply that the anammox bacteria have the genes necessary to synthesize peptidoglycan-like cell wall structures. In this study, we investigated the effects of two antibacterial agents that target the integrity and synthesis of peptidoglycan (lysozyme and penicillin G) on the anammox bacterium Kuenenia stuttgartiensis. The effects of these compounds were determined in both short-term batch incubations and long-term (continuous-cultivation) growth experiments in membrane bioreactors. Lysozyme at 1 g/liter (20 mM EDTA) lysed anammox cells in less than 60 min, whereas penicillin G did not have any observable short-term effects on anammox activity. Penicillin G (0.5, 1, and 5 g/liter) reversibly inhibited the growth of anammox bacteria in continuous-culture experiments. Furthermore, transcriptome analyses of the penicillin G-treated reactor and the control reactor revealed that penicillin G treatment resulted in a 10-fold decrease in the ribosome levels of the cells. One of the cell division proteins (Kustd1438) was downregulated 25-fold. Our results suggested that anammox bacteria contain peptidoglycan-like components in their cell wall that can be targeted by lysozyme and penicillin G-sensitive proteins were involved in their synthesis. Finally, we showed that a continuous membrane reactor system with free-living planktonic cells was a very powerful tool to study the physiology of slow-growing microorganisms under physiological conditions.
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90
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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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91
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Mun SH, Joung DK, Kim YS, Kang OH, Kim SB, Seo YS, Kim YC, Lee DS, Shin DW, Kweon KT, Kwon DY. Synergistic antibacterial effect of curcumin against methicillin-resistant Staphylococcus aureus. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2013; 20:714-8. [PMID: 23537748 DOI: 10.1016/j.phymed.2013.02.006] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/20/2012] [Accepted: 02/19/2013] [Indexed: 05/23/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) are spread among infected patients, with infection rates increasing at an alarming rate. Furthermore, increased resistance to antibiotics has resulted in serious challenges in the treatment of infectious diseases worldwide. Under the selection pressure of exposure to antibiotics, microorganisms evolve to survive against the new conditions imposed by therapy. Therefore, there exists a need to develop alternative natural or combination drug therapies. Curcumin (CCM), a natural polyphenolic flavonoid isolated from the rhizome of a plant, Curcuma longa Linné., has been found to possess many beneficial biological activities. The aim of this study was to investigate the synergistic effect of curcumin and antibiotics as well as to determine the antibacterial activity of CCM against specific MRSA strains. The antibacterial activity of CCM was assessed by the broth microdilution method (by calculating the minimal inhibitory concentration [MIC]), checkerboard dilution test, and time-kill assay. Antimicrobial activity of CCM was observed against all tested strains. The MICs of CCM against 10 strains of S. aureus ranged from 125 to 250 μg/ml. In the checkerboard test, CCM markedly reduced the MICs of the antibiotics oxacillin (OXI), ampicillin (AMP), ciprofloxacin (CIP), and norfloxacin (NOR) used against MRSA. The time-kill curves showed that a combined CCM and OXI treatment reduced the bacterial counts below the lowest detectable limit after 24h. This study suggested that CCM reduced the MICs of several antibiotics tested, notably of OXI, AMP, CIP, and NOR, and that CCM in combination with antibiotics could lead to the development of new combination of antibiotics against MRSA infection.
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Affiliation(s)
- Su-Hyun Mun
- College of Pharmacy and Wonkwang-Oriental Medicines Research Institute, Institute of Biotechnology, Wonkwang University, Jeonbuk 570-749, Republic of Korea
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92
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Zeng X, Lin J. Beta-lactamase induction and cell wall metabolism in Gram-negative bacteria. Front Microbiol 2013; 4:128. [PMID: 23734147 PMCID: PMC3660660 DOI: 10.3389/fmicb.2013.00128] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 05/04/2013] [Indexed: 11/13/2022] Open
Abstract
Production of beta-lactamases, the enzymes that degrade beta-lactam antibiotics, is the most widespread and threatening mechanism of antibiotic resistance. In the past, extensive research has focused on the structure, function, and ecology of beta-lactamases while limited efforts were placed on the regulatory mechanisms of beta-lactamases. Recently, increasing evidence demonstrate a direct link between beta-lactamase induction and cell wall metabolism in Gram-negative bacteria. Specifically, expression of beta-lactamase could be induced by the liberated murein fragments, such as muropeptides. This article summarizes current knowledge on cell wall metabolism, beta-lactam antibiotics, and beta-lactamases. In particular, we comprehensively reviewed recent studies on the beta-lactamase induction by muropeptides via two major molecular mechanisms (the AmpG-AmpR-AmpC pathway and BlrAB-like two-component regulatory system) in Gram-negative bacteria. The signaling pathways for beta-lactamase induction offer a broad array of promising targets for the discovery of new antibacterial drugs used for combination therapies. Therefore, to develop effective mitigation strategies against the widespread beta-lactam resistance, examination of the molecular basis of beta-lactamase induction by cell wall fragment is highly warranted.
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Affiliation(s)
| | - Jun Lin
- Department of Animal Science, The University of TennesseeKnoxville, TN, USA
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93
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Abstract
β-Lactam antibiotics are one of the most important antibiotic classes but are plagued by problems of resistance, and the development of new β-lactam antibiotics through side-chain modification of existing β-lactam classes is not keeping pace with resistance development. In this JOCSynopsis, we summarize small molecule strategies to overcome resistance to β-lactam antibiotics. These approaches include the development of β-lactamase inhibitors and compounds that interfere with the ability of the bacteria to sense an antibiotic threat and activate their resistance mechanisms.
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Affiliation(s)
- Roberta J Worthington
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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94
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Genetic nature and virulence of community-associated methicillin-resistant Staphylococcus aureus. Biomedicine (Taipei) 2013. [DOI: 10.1016/j.biomed.2012.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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95
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Pillai MM, Latha R, Sarkar G. Detection of methicillin resistance in Staphylococcus aureus by polymerase chain reaction and conventional methods: a comparative study. J Lab Physicians 2013; 4:83-8. [PMID: 23441000 PMCID: PMC3574503 DOI: 10.4103/0974-2727.105587] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide, which has emerged over the past 30 years as a leading cause of both nosocomial and community-acquired infections. Accurate and rapid identification of MRSA in clinical specimens is essential for timely decision on effective antimicrobial chemotherapy. Aim: The present study was conducted to compare two conventional phenotypic methods, oxacillin disk diffusion (ODD) method and mannitol salt agar (MSA) with oxacillin, with polymerase chain reaction (PCR) for mecA gene (as standard). Materials and Methods: A total of 165 consecutive clinical isolates of S. aureus received at the Department of Microbiology in our tertiary care teaching hospital were included in the study. All the isolates were subjected to ODD (1 μg) method, culture in MSA with oxacillin, and PCR for mecA gene. Results: The sensitivity and specificity of ODD test were found to be 93.5% (86.4-97.3%) and 83.5% (79.2-85.8%), respectively, and that of MSA with oxacillin were found to be 87.1% (79.5-92.3%) and 89.3% (84.8-92.5%), respectively. The time taken for diagnosing MRSA by conventional methods is 48-72 h, which is more as compared to PCR which takes 18-24 h. Conclusion: This study recommends advocating PCR for mecA gene on a regular basis for detecting methicillin resistance in S. aureus isolates isolated from sterile body fluids or from special units such as intensive care units.
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Affiliation(s)
- Manju M Pillai
- Department of Biochemistry, A.V. Medical College, Pondicherry, India
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96
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Abstract
Recently, a novel variant of mecA known as mecC (mecA(LGA251)) was identified in Staphylococcus aureus isolates from both humans and animals. In this study, we identified a Staphylococcus xylosus isolate that harbors a new allotype of the mecC gene, mecC1. Whole-genome sequencing revealed that mecC1 forms part of a class E mec complex (mecI-mecR1-mecC1-blaZ) located at the orfX locus as part of a likely staphylococcal cassette chromosome mec element (SCCmec) remnant, which also contains a number of other genes present on the type XI SCCmec.
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97
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Abstract
β-Lactam antibiotics are the most commonly used antibacterial agents and growing resistance to these drugs is a concern. Metallo-β-lactamases are a diverse set of enzymes that catalyze the hydrolysis of a broad range of β-lactam drugs including carbapenems. This diversity is reflected in the observation that the enzyme mechanisms differ based on whether one or two zincs are bound in the active site that, in turn, is dependent on the subclass of β-lactamase. The dissemination of the genes encoding these enzymes among Gram-negative bacteria has made them an important cause of resistance. In addition, there are currently no clinically available inhibitors to block metallo-β-lactamase action. This review summarizes the numerous studies that have yielded insights into the structure, function, and mechanism of action of these enzymes.
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Affiliation(s)
- Timothy Palzkill
- Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030, USA.
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98
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Kim C, Milheiriço C, Gardete S, Holmes MA, Holden MTG, de Lencastre H, Tomasz A. Properties of a novel PBP2A protein homolog from Staphylococcus aureus strain LGA251 and its contribution to the β-lactam-resistant phenotype. J Biol Chem 2012; 287:36854-63. [PMID: 22977239 PMCID: PMC3481288 DOI: 10.1074/jbc.m112.395962] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains show strain-to-strain variation in resistance level, in genetic background, and also in the structure of the chromosomal cassette (SCCmec) that carries the resistance gene mecA. In contrast, strain-to-strain variation in the sequence of the mecA determinant was found to be much more limited among MRSA isolates examined so far. The first exception to this came with the recent identification of MRSA strain LGA251, which carries a new homolog of this gene together with regulatory elements mecI/mecR that also have novel, highly divergent structures. After cloning and purification in Escherichia coli, PBP2A(LGA), the protein product of the new mecA homolog, showed aberrant mobility in SDS-PAGE, structural instability and loss of activity at 37 °C, and a higher relative affinity for oxacillin as compared with cefoxitin. The mecA homolog free of its regulatory elements was cloned into a plasmid and introduced into the background of the β-lactam-susceptible S. aureus strain COL-S. In this background, the mecA homolog expressed a high-level resistance to cefoxitin (MIC = 400 μg/ml) and a somewhat lower resistance to oxacillin (minimal inhibitory concentration = 200 μg/ml). Similar to PBP2A, the protein homolog PBP2A(LGA) was able to replace the essential function of the S. aureus PBP2 for growth. In contrast to PBP2A, PBP2A(LGA) did not depend on the transglycosylase activity of the native PBP2 for expression of high level resistance to oxacillin, suggesting that the PBP2A homolog may preferentially cooperate with a monofunctional transglycosylase as the alternative source of transglycosylase activity.
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Affiliation(s)
- Choonkeun Kim
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York 10065, USA
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99
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Zhao Y, Verma V, Belcheva A, Singh A, Fridman M, Golemi-Kotra D. Staphylococcus aureus methicillin-resistance factor fmtA is regulated by the global regulator SarA. PLoS One 2012; 7:e43998. [PMID: 22952845 PMCID: PMC3431356 DOI: 10.1371/journal.pone.0043998] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 07/26/2012] [Indexed: 11/30/2022] Open
Abstract
fmtA encodes a low-affinity penicillin binding protein in Staphylococcus aureus. It is part of the core cell wall stimulon and is involved in methicillin resistance in S. aureus. Here, we report that the transcription factor, SarA, a pleiotropic regulator of virulence genes in S. aureus, regulates the expression of fmtA. In vitro binding studies with purified SarA revealed that it binds to specific sites within the 541-bp promoter region of fmtA. Mutation of a key residue of the regulatory activity of SarA (Arg90) abolished binding of SarA to the fmtA promoter, suggesting that SarA binds specifically to the fmtA promoter region. In vivo analysis of the fmtA promoter using a lux operon reporter fusion show high level expression following oxacillin induction, which was abrogated in a sarA mutant strain. These data suggest that SarA is essential for the induction of fmtA expression by cell wall-specific antibiotics. Further, in vitro transcription studies show that SarA enhances fmtA transcription and suggest that regulation of fmtA could be via a SigA-dependent mechanism. Overall, our results show that SarA plays a direct role in the regulation of fmtA expression via binding to the fmtA promoter.
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Affiliation(s)
- Yinglu Zhao
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | - Vidhu Verma
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | | | - Atul Singh
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | - Michael Fridman
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Dasantila Golemi-Kotra
- Department of Biology, York University, Toronto, Ontario, Canada
- Department of Chemistry, York University, Toronto, Ontario, Canada
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100
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Arêde P, Milheiriço C, de Lencastre H, Oliveira DC. The anti-repressor MecR2 promotes the proteolysis of the mecA repressor and enables optimal expression of β-lactam resistance in MRSA. PLoS Pathog 2012; 8:e1002816. [PMID: 22911052 PMCID: PMC3406092 DOI: 10.1371/journal.ppat.1002816] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 06/09/2012] [Indexed: 01/20/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen, which is cross-resistant to virtually all β-lactam antibiotics. MRSA strains are defined by the presence of mecA gene. The transcription of mecA can be regulated by a sensor-inducer (MecR1) and a repressor (MecI), involving a unique series of proteolytic steps. The induction of mecA by MecR1 has been described as very inefficient and, as such, it is believed that optimal expression of β-lactam resistance by MRSA requires a non-functional MecR1-MecI system. However, in a recent study, no correlation was found between the presence of functional MecR1-MecI and the level of β-lactam resistance in a representative collection of epidemic MRSA strains. Here, we demonstrate that the mecA regulatory locus consists, in fact, of an unusual three-component arrangement containing, in addition to mecR1-mecI, the up to now unrecognized mecR2 gene coding for an anti-repressor. The MecR2 function is essential for the full induction of mecA expression, compensating for the inefficient induction of mecA by MecR1 and enabling optimal expression of β-lactam resistance in MRSA strains with functional mecR1-mecI regulatory genes. Our data shows that MecR2 interacts directly with MecI, destabilizing its binding to the mecA promoter, which results in the repressor inactivation by proteolytic cleavage, presumably mediated by native cytoplasmatic proteases. These observations point to a revision of the current model for the transcriptional control of mecA and open new avenues for the design of alternative therapeutic strategies for the treatment of MRSA infections. Moreover, these findings also provide important insights into the complex evolutionary pathways of antibiotic resistance and molecular mechanisms of transcriptional regulation in bacteria. Methicillin-resistance Staphylococcus aureus (MRSA) is an important human pathogen, causing a wide range of infections. MRSA strains are resistant to virtually all β-lactam antibiotics and often are also resistant to many other classes of antibiotics, leaving physicians with few therapeutic options. MRSA is defined by the presence of the mecA gene. The induction of mecA transcription in response to β-lactams involves a unique series of proteolytic steps and some critical details of this signal transduction mechanism are still illusive. For instance, it is not fully explained why the induction of mecA by its cognate regulatory genes mecR1-mecI appears to be very inefficient and it is not clear if the observed MecI repressor proteolysis is mediated directly by the activated MecR1 sensor-inducer. In this study, we demonstrate that the mecA regulatory locus is not a two-component system but instead it is a three-component system containing the previously unrecognized anti-repressor mecR2 gene. MecR2 disturbs the binding of the repressor MecI to the mecA promoter, which leads to its proteolytic inactivation independently from MecR1. Moreover, our data shows that in the presence of functional mecR1-mecI genes, mecR2 is essential for a robust induction of mecA transcription and, as consequence, for the optimal expression of β-lactam resistance.
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Affiliation(s)
- Pedro Arêde
- CREM, Department of Life Sciences, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Catarina Milheiriço
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Hermínia de Lencastre
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, United States of America
| | - Duarte C. Oliveira
- CREM, Department of Life Sciences, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- * E-mail:
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