1
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Singh KV, Galloway-Peña J, Montealegre MC, Dong X, Murray BE. Genomic context as well as sequence of both psr and penicillin-binding protein 5 contributes to β-lactam resistance in Enterococcus faecium. mBio 2024; 15:e0017024. [PMID: 38564699 PMCID: PMC11077988 DOI: 10.1128/mbio.00170-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 03/04/2024] [Indexed: 04/04/2024] Open
Abstract
Penicillin-binding protein 5 (PBP5) of Enterococcus faecium (Efm) is vital for ampicillin resistance (AMP-R). We previously designated three forms of PBP5, namely, PBP5-S in Efm clade B strains [ampicillin susceptible (AMP-S)], PBP5-S/R (AMP-S or R), and PBP5-R (AMP-R) in clade A strains. Here, pbp5 deletion resulted in a marked reduction in AMP minimum inhibitory concentrations (MICs) to 0.01-0.09 µg/mL for clade B and 0.12-0.19 µg/mL for clade A strains; in situ complementation restored parental AMP MICs. Using D344SRF (lacking ftsW/psr/pbp5), constructs with ftsWA/psrA (from a clade A1 strain) cloned upstream of pbp5-S and pbp5-S/R alleles resulted in modest increases in MICs to 3-8 µg/mL, while high MICs (>64 µg/mL) were seen using pbp5 from A1 strains. Next, using ftsW ± psr from clade B and clade A/B and B/A hybrid constructs, the presence of psrB, even alone or in trans, resulted in much lower AMP MICs (3-8 µg/mL) than when psrA was present (MICs >64 µg/mL). qRT PCR showed relatively greater pbp5 expression (P = 0.007) with pbp5 cloned downstream of clade A1 ftsW/psr (MIC >128 µg/mL) vs when cloned downstream of clade B ftsW/psr (MIC 4-16 µg/mL), consistent with results in western blots. In conclusion, we report the effect of clade A vs B psr on AMP MICs as well as the impact of pbp5 alleles from different clades. While previously, Psr was not thought to contribute to AMP MICs in Efm, our results showed that the presence of psrB resulted in a major decrease in Efm AMP MICs. IMPORTANCE The findings of this study shed light on ampicillin resistance in Enterococcus faecium clade A strains. They underscore the significance of alterations in the amino acid sequence of penicillin-binding protein 5 (PBP5) and the pivotal role of the psr region in PBP5 expression and ampicillin resistance. Notably, the presence of a full-length psrB leads to reduced PBP5 expression and lower minimum inhibitory concentrations (MICs) of ampicillin compared to the presence of a shorter psrA, regardless of the pbp5 allele involved. Additionally, clade B E. faecium strains exhibit lower AMP MICs when both psr alleles from clades A and B are present, although it is important to consider other distinctions between clade A and B strains that may contribute to this effect. It is intriguing to note that the divergence between clade A and clade B E. faecium and the subsequent evolution of heightened AMP MICs in hospital-associated strains appear to coincide with changes in Pbp5 and psr. These changes in psr may have resulted in an inactive Psr, facilitating increased PBP5 expression and greater ampicillin resistance. These results raise the possibility that a mimicker of PsrB, if one could be designed, might be able to lower MICs of ampicillin-resistant E. faecium, thus potentially resorting ampicillin to our therapeutic armamentarium for this species.
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Affiliation(s)
- Kavindra V. Singh
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA
| | - Jessica Galloway-Peña
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA
| | - Maria Camila Montealegre
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA
- Department of Microbiology and Infectious Diseases, University of Texas Health Science Center, Houston, Texas, USA
| | - Xingxing Dong
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA
| | - Barbara E. Murray
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA
- Department of Microbiology and Infectious Diseases, University of Texas Health Science Center, Houston, Texas, USA
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2
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Turner J, Muraoka A, Bedenbaugh M, Childress B, Pernot L, Wiencek M, Peterson YK. The Chemical Relationship Among Beta-Lactam Antibiotics and Potential Impacts on Reactivity and Decomposition. Front Microbiol 2022; 13:807955. [PMID: 35401470 PMCID: PMC8988990 DOI: 10.3389/fmicb.2022.807955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/14/2022] [Indexed: 12/05/2022] Open
Abstract
Beta-lactam antibiotics remain one of the most commonly prescribed drug classes, but they are limited by their propensity to cause hypersensitivity reactions (e.g., from allergy to anaphylaxis) as well as by the emergence of bacteria with a myriad of resistance mechanisms such as β-lactamases. While development efforts continue to focus on overcoming resistance, there are ongoing concerns regarding cross-contamination of β-lactams during manufacturing and compounding of these drugs. Additionally, there is a need to reduce levels of drugs such as β-lactam antibiotics in waste-water to mitigate the risk of environmental exposure. To help address future development of effective remediation chemistries and processes, it is desired to better understand the structural relationship among the most common β-lactams. This study includes the creation of a class-wide structural ordering of the entire β-lactam series, including both United States Food and Drug Association (US-FDA)-approved drugs and experimental therapies. The result is a structural relational map: the “Lactamome,” which positions each substance according to architecture and chemical end-group. We utilized a novel method to compare the structural relationships of β-lactam antibiotics among the radial cladogram and describe the positioning with respect to efficacy, resistance to hydrolysis, reported hypersensitivity, and Woodward height. The resulting classification scheme may help with the development of broad-spectrum treatments that reduce the risk of occupational exposure and negative environmental impacts, assist practitioners with avoiding adverse patient reactions, and help direct future drug research.
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Affiliation(s)
- Jonathan Turner
- College of Medicine, Medical University of South Carolina, Charleston, SC, United States
- College of Pharmacy, Medical University of South Carolina, Charleston, SC, United States
| | - Alyssa Muraoka
- College of Pharmacy, Medical University of South Carolina, Charleston, SC, United States
| | | | - Blaine Childress
- South Carolina Research Authority, Greenville, SC, United States
| | | | | | - Yuri K. Peterson
- College of Pharmacy, Medical University of South Carolina, Charleston, SC, United States
- *Correspondence: Yuri K. Peterson,
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Akhlaghi N, Najafpour-Darzi G. Multifunctional metal-chelated phosphonate/Fe3O4 magnetic nanocomposite particles for defeating antibiotic-resistant bacteria. POWDER TECHNOL 2021. [DOI: 10.1016/j.powtec.2021.01.078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Turner JM, Connolly KL, Aberman KE, Fonseca JC, Singh A, Jerse AE, Nicholas RA, Davies C. Molecular Features of Cephalosporins Important for Activity against Antimicrobial-Resistant Neisseria gonorrhoeae. ACS Infect Dis 2021; 7:293-308. [PMID: 33533239 PMCID: PMC9847585 DOI: 10.1021/acsinfecdis.0c00400] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The increasing prevalence of Neisseria gonorrhoeae strains exhibiting decreased susceptibility to extended-spectrum cephalosporins (ESCs) presents a challenge for the successful treatment of gonorrhea infections. To address this challenge, we evaluated a panel of 23 cephalosporins against penicillin-binding protein 2 (PBP2) from the ESC-resistant (ESCR) N. gonorrhoeae strain H041 to determine which molecular features are important for antimicrobial activity. Structure-activity relationships (SARs) developed from acylation rate constants against PBP2 and antimicrobial susceptibilities against the H041 strain of N. gonorrhoeae, and interpreted against docking models, reveal that cephalosporins possessing large, lipophilic R1 side chains and electronegative R2 side chains with planar groups are associated with higher acylation rates against PBP2, but also that these same amphipathic features can lower antimicrobial activity. Based on these studies, we tested cefoperazone, one of the most effective ESCs for targeting PBP2, in the female mouse model infected with H041 and showed that it was equally or more effective than ceftriaxone or gentamicin for clearing infections. Taken together, our results reveal that two U.S. Food and Drug Administration (FDA)-approved agents (cefoperazone, ceftaroline) and one FDA-qualified infectious disease product (ceftobiprole) have potential as first-line treatments for gonorrhea and provide a framework for the future design of cephalosporins with improved activity against ESC-resistant N. gonorrhoeae.
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Affiliation(s)
- Jonathan M. Turner
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Kristie L. Connolly
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD 20814
| | - Kate E. Aberman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Joseph C. Fonseca
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Avinash Singh
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Ann E. Jerse
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD 20814
| | - Robert A. Nicholas
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Christopher Davies
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425,Corresponding author: Department of Biochemistry & Molecular Biology, University of South Alabama, 5795 USA Drive North, Mobile, AL 36688. Tel +1 (651) 460-6659;
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Guevara Salazar JA, Morán Díaz JR, Ramírez Segura E, Trujillo Ferrara JG. What are the origins of growing microbial resistance? Both Lamarck and Darwin were right. Expert Rev Anti Infect Ther 2020; 19:563-569. [PMID: 33073640 DOI: 10.1080/14787210.2021.1839418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Microorganisms of clinical importance frequently develop resistance to drug therapy, now a growing problem. The experience with Mycobacterium tuberculosis is a representative example of increasing multi-drug resistance. To avoid reaching a crisis in which patients could be left without adequate treatment, a new strategy is needed. Anti-microbial therapy has historically targeted the mechanisms rather than origin of drug resistance, thus allowing microorganisms to adapt and survive. AREAS COVERED This contribution analyses the historical development (1943-2020) of the evolution of multi-drug resistance by M. tuberculosis strains in light of Darwin's and Lamarck's theories of evolution. EXPERT OPINION Regarding the molecular origin of microbial drug resistance, genetic mutations and epigenetic modifications are known to participate. The analysis of the history of drug resistance by M. tuberculosis evidences a gradual development of resistance to some antibiotics, undoubtedly due to random mutations together with natural selection based on environmental pressures (e.g., antibiotics), representing Darwin's idea. More rapid adaptation of M. tuberculosis to new antibiotic treatments has also occurred, probably because of heritable acquired characteristics, evidencing Lamarck's proposal. Therefore, microbial infections should be treated with an antibiotic producing null or low mutagenic activity along with a resistance inhibitor, preferably in a single medication.
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Affiliation(s)
- Juan Alberto Guevara Salazar
- Departamento De Farmacología, Escuela Superior De Medicina, Instituto Politécnico Nacional, Ciudad De México, CDMX, Mexico
| | - Jessica Rubí Morán Díaz
- Departamento De Farmacología, Escuela Superior De Medicina, Instituto Politécnico Nacional, Ciudad De México, CDMX, Mexico
| | - Enrique Ramírez Segura
- Laboratorio De Bioquímica Médica, Escuela Superior De Medicina, Instituto Politécnico Nacional, Ciudad De México, CDMX, Mexico
| | - José Guadalupe Trujillo Ferrara
- Laboratorio De Bioquímica Médica, Escuela Superior De Medicina, Instituto Politécnico Nacional, Ciudad De México, CDMX, Mexico
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6
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Hrichi H, Elkanzi NAA, Bakr RB. Novel Β-lactams and Thiazolidinone Derivatives from 1,4-dihydroquinoxaline Schiff’s Base: Synthesis, Antimicrobial Activity and Molecular Docking Studies. CHEMISTRY JOURNAL OF MOLDOVA 2020. [DOI: 10.19261/cjm.2019.647] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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7
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Halaji M, Shahidi S, Atapour A, Ataei B, Feizi A, Havaei SA. Characterization of Extended-Spectrum β-Lactamase-Producing Uropathogenic Escherichia coli Among Iranian Kidney Transplant Patients. Infect Drug Resist 2020; 13:1429-1437. [PMID: 32523361 PMCID: PMC7237106 DOI: 10.2147/idr.s248572] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/05/2020] [Indexed: 12/21/2022] Open
Abstract
Introduction The aim of this study was to investigate the antimicrobial susceptibility pattern and the presence of ESBLs among the uropathogenic Escherichia coli (UPEC) isolated from kidney transplant patients (KTP) and community-acquired urinary tract infections (UTIs) using phenotypic and molecular methods. Materials and Methods A total of 111 pure cultures of UPEC isolates were collected from 65 and 46 of non-KTP and KTPs with UTIs. The pattern and ESBL production of the strains were evaluated. PCR reaction to detect the presence of bla SHV, bla TEM, and bla CTX-M genes was performed. Results The results revealed that most of UPEC isolates obtained from KTPs and control group were resistant to trimethoprim/sulfamethoxazole (84.8% vs 46.2%), while carbapenems (100% sensitivity) were the most effective against UPEC isolates. ESBL-producing strains were significantly more frequent in KTPs compared with control group (43.5% vs 23.1%, P = 0.021). The molecular results revealed that 53.2% (59/111), 45% (50/111), and 5.4% (6/111) of isolates harbored bla CTX-M, bla TEM, and bla SHV genes, respectively. Of the genes investigated, bla CTX-M and bla TEM genes were significantly higher among KTP than the control group. Conclusion Our results showed a high proportion of multidrug-resistant and ESBL-producing isolates, which most of them harbor blaCTX-M. A significant high co-resistance to different classes of antibiotics was reported from ESBL-producing UPEC from KTPs, which remains a serious clinical challenge.
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Affiliation(s)
- Mehrdad Halaji
- Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahrzad Shahidi
- Isfahan Kidney Diseases Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Abdolamir Atapour
- Isfahan Kidney Diseases Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Behrooz Ataei
- Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Awat Feizi
- Department of Biostatistics and Epidemiology, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Seyed Asghar Havaei
- Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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8
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Halaji M, Shahidi S, Atapour A, Ataei B, Feizi A, Havaei SA. <p>Characterization of Extended-Spectrum β-Lactamase-Producing Uropathogenic <em>Escherichia coli</em> Among Iranian Kidney Transplant Patients</p>. Infect Drug Resist 2020. [DOI: 10.2147/idr.s248572 and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Multiple Low-Reactivity Class B Penicillin-Binding Proteins Are Required for Cephalosporin Resistance in Enterococci. Antimicrob Agents Chemother 2020; 64:AAC.02273-19. [PMID: 32041714 DOI: 10.1128/aac.02273-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/02/2020] [Indexed: 01/16/2023] Open
Abstract
Enterococcus faecalis and Enterococcus faecium are commensals of the gastrointestinal tract of most terrestrial organisms, including humans, and are major causes of health care-associated infections. Such infections are difficult or impossible to treat, as the enterococcal strains responsible are often resistant to multiple antibiotics. One intrinsic resistance trait that is conserved among E. faecalis and E. faecium is cephalosporin resistance, and prior exposure to cephalosporins is one of the most well-known risk factors for acquisition of an enterococcal infection. Cephalosporins inhibit peptidoglycan biosynthesis by acylating the active-site serine of penicillin-binding proteins (PBPs) to prevent the PBPs from catalyzing cross-linking during peptidoglycan synthesis. For decades, a specific PBP (known as Pbp4 or Pbp5) that exhibits low reactivity toward cephalosporins has been thought to be the primary PBP required for cephalosporin resistance. We analyzed other PBPs and report that in both E. faecalis and E. faecium, a second PBP, PbpA(2b), is also required for resistance; notably, the cephalosporin ceftriaxone exhibits a lethal effect on the ΔpbpA mutant. Strikingly, PbpA(2b) exhibits low intrinsic reactivity with cephalosporins in vivo and in vitro Unlike the Δpbp5 mutant, the ΔpbpA mutant exhibits a variety of phenotypic defects in growth kinetics, cell wall integrity, and cellular morphology, indicating that PbpA(2b) and Pbp5(4) are not functionally redundant and that PbpA(2b) plays a more central role in peptidoglycan synthesis. Collectively, our results shift the current understanding of enterococcal cephalosporin resistance and suggest a model in which PbpA(2b) and Pbp5(4) cooperate to coordinately mediate peptidoglycan cross-linking in the presence of cephalosporins.
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10
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Pidgeon SE, Apostolos AJ, Nelson JM, Shaku M, Rimal B, Islam MN, Crick DC, Kim SJ, Pavelka MS, Kana BD, Pires MM. L,D-Transpeptidase Specific Probe Reveals Spatial Activity of Peptidoglycan Cross-Linking. ACS Chem Biol 2019; 14:2185-2196. [PMID: 31487148 PMCID: PMC6804245 DOI: 10.1021/acschembio.9b00427] [Citation(s) in RCA: 30] [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: 05/31/2019] [Accepted: 09/05/2019] [Indexed: 02/02/2023]
Abstract
Peptidoglycan (PG) is a cross-linked, meshlike scaffold endowed with the strength to withstand the internal pressure of bacteria. Bacteria are known to heavily remodel their peptidoglycan stem peptides, yet little is known about the physiological impact of these chemical variations on peptidoglycan cross-linking. Furthermore, there are limited tools to study these structural variations, which can also have important implications on cell wall integrity and host immunity. Cross-linking of peptide chains within PG is an essential process, and its disruption thereof underpins the potency of several classes of antibiotics. Two primary cross-linking modes have been identified that are carried out by D,D-transpeptidases and L,D-transpeptidases (Ldts). The nascent PG from each enzymatic class is structurally unique, which results in different cross-linking configurations. Recent advances in PG cellular probes have been powerful in advancing the understanding of D,D-transpeptidation by Penicillin Binding Proteins (PBPs). In contrast, no cellular probes have been previously described to directly interrogate Ldt function in live cells. Herein, we describe a new class of Ldt-specific probes composed of structural analogs of nascent PG, which are metabolically incorporated into the PG scaffold by Ldts. With a panel of tetrapeptide PG stem mimics, we demonstrated that subtle modifications such as amidation of iso-Glu can control PG cross-linking. Ldt probes were applied to quantify and track the localization of Ldt activity in Enterococcus faecium, Mycobacterium smegmatis, and Mycobacterium tuberculosis. These results confirm that our Ldt probes are specific and suggest that the primary sequence of the stem peptide can control Ldt cross-linking levels. We anticipate that unraveling the interplay between Ldts and other cross-linking modalities may reveal the organization of the PG structure in relation to the spatial localization of cross-linking machineries.
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Affiliation(s)
- Sean E. Pidgeon
- Department
of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Alexis J. Apostolos
- Department
of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Julia M. Nelson
- Department
of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Moagi Shaku
- DST/NRF
Centre of Excellence for Biomedical TB Research, School of Pathology,
Faculty of Health Sciences, University of
the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg 2000, South Africa
- MRC-CAPRISA
HIV-TB Pathogenesis and Treatment Research Unit, Centre for the AIDS Programme of Research in South Africa, CAPRISA, Durban 4001, South Africa
| | - Binayak Rimal
- Institute
of Biomedical Studies, Baylor University, Waco, Texas 76798, United States
| | - M. Nurul Islam
- Mycobacteria
Research Laboratories, Department of Microbiology, Immunology, and
Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Dean C. Crick
- Mycobacteria
Research Laboratories, Department of Microbiology, Immunology, and
Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Sung Joon Kim
- Department
of Chemistry, Howard University, Washington, DC 20059, United States
| | - Martin S. Pavelka
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, Rochester, New York 14642, United States
| | - Bavesh D. Kana
- DST/NRF
Centre of Excellence for Biomedical TB Research, School of Pathology,
Faculty of Health Sciences, University of
the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg 2000, South Africa
- MRC-CAPRISA
HIV-TB Pathogenesis and Treatment Research Unit, Centre for the AIDS Programme of Research in South Africa, CAPRISA, Durban 4001, South Africa
| | - Marcos M. Pires
- Department
of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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Adaptation to Adversity: the Intermingling of Stress Tolerance and Pathogenesis in Enterococci. Microbiol Mol Biol Rev 2019; 83:83/3/e00008-19. [PMID: 31315902 DOI: 10.1128/mmbr.00008-19] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Enterococcus is a diverse and rugged genus colonizing the gastrointestinal tract of humans and numerous hosts across the animal kingdom. Enterococci are also a leading cause of multidrug-resistant hospital-acquired infections. In each of these settings, enterococci must contend with changing biophysical landscapes and innate immune responses in order to successfully colonize and transit between hosts. Therefore, it appears that the intrinsic durability that evolved to make enterococci optimally competitive in the host gastrointestinal tract also ideally positioned them to persist in hospitals, despite disinfection protocols, and acquire new antibiotic resistances from other microbes. Here, we discuss the molecular mechanisms and regulation employed by enterococci to tolerate diverse stressors and highlight the role of stress tolerance in the biology of this medically relevant genus.
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12
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Structural and Regulatory Changes in PBP4 Trigger Decreased β-Lactam Susceptibility in Enterococcus faecalis. mBio 2018; 9:mBio.00361-18. [PMID: 29615500 PMCID: PMC5885037 DOI: 10.1128/mbio.00361-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterococcus faecalis strains resistant to penicillin and ampicillin are rare and have been associated with increases in quantities of low-affinity penicillin-binding protein 4 (PBP4) or with amino acid substitutions in PBP4. We report an E. faecalis strain (LS4828) isolated from a prosthetic knee joint that was subjected to long-term exposure to aminopenicillins. Subsequent cultures yielded E. faecalis with MICs of penicillins and carbapenems higher than those for wild-type strain E. faecalis JH2-2. Sequence analysis of the pbp4 gene of LS4828 compared to that of JH2-2 revealed two point mutations with amino acid substitutions (V223I, A617T) and deletion of an adenine from the region upstream of the predicted pbp4 -35 promoter sequence (UP region). Purified PBP4 from LS4828 exhibited less affinity for Bocillin FL than did PBP4 from JH2-2, which was recapitulated by purified PBP4 containing only the A617T mutation. Differential scanning fluorimetry studies showed that the LS4828 and A617T variants are destabilized compared to wild-type PBP4. Further, reverse transcription-PCR indicated increased transcription of pbp4 in LS4828 and Western blot analysis with polyclonal PBP4 antibody revealed greater quantities of PBP4 in LS4828 than in JH2-2 lysates and membrane preparations. Placing the promoter regions from LS4828 or JH2-2 upstream of a green fluorescent protein reporter gene confirmed that the adenine deletion was associated with increased transcription. Together, these data suggest that the reduced susceptibility to β-lactam antibiotics observed in E. faecalis LS4828 results from a combination of both increased expression and remodeling of the active site, resulting in reduced affinity for penicillins and carbapenems.IMPORTANCEEnterococcus faecalis is an important cause of community-acquired and nosocomial infections and creates therapeutic dilemmas because of its frequent resistance to several classes of antibiotics. We report an E. faecalis strain with decreased ampicillin and imipenem susceptibility isolated after prolonged courses of aminopenicillin therapy for a prosthetic joint infection. Its reduced susceptibility is attributable to a combination of increased quantities of low-affinity PBP4 and an amino acid substitution in proximity to the active site that destabilizes the protein. Our findings provide a cautionary tale for clinicians who elect to "suppress" infections in prosthetic joints and offer novel insights into the interaction of β-lactam antibiotics with low-affinity PBP4. These insights will help inform future efforts to develop therapeutics capable of inhibiting clinical enterococcal strains.
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13
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Durand-Réville TF, Guler S, Comita-Prevoir J, Chen B, Bifulco N, Huynh H, Lahiri S, Shapiro AB, McLeod SM, Carter NM, Moussa SH, Velez-Vega C, Olivier NB, McLaughlin R, Gao N, Thresher J, Palmer T, Andrews B, Giacobbe RA, Newman JV, Ehmann DE, de Jonge B, O'Donnell J, Mueller JP, Tommasi RA, Miller AA. ETX2514 is a broad-spectrum β-lactamase inhibitor for the treatment of drug-resistant Gram-negative bacteria including Acinetobacter baumannii. Nat Microbiol 2017; 2:17104. [PMID: 28665414 DOI: 10.1038/nmicrobiol.2017.104] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 05/25/2017] [Indexed: 11/09/2022]
Abstract
Multidrug-resistant (MDR) bacterial infections are a serious threat to public health. Among the most alarming resistance trends is the rapid rise in the number and diversity of β-lactamases, enzymes that inactivate β-lactams, a class of antibiotics that has been a therapeutic mainstay for decades. Although several new β-lactamase inhibitors have been approved or are in clinical trials, their spectra of activity do not address MDR pathogens such as Acinetobacter baumannii. This report describes the rational design and characterization of expanded-spectrum serine β-lactamase inhibitors that potently inhibit clinically relevant class A, C and D β-lactamases and penicillin-binding proteins, resulting in intrinsic antibacterial activity against Enterobacteriaceae and restoration of β-lactam activity in a broad range of MDR Gram-negative pathogens. One of the most promising combinations is sulbactam-ETX2514, whose potent antibacterial activity, in vivo efficacy against MDR A. baumannii infections and promising preclinical safety demonstrate its potential to address this significant unmet medical need.
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Affiliation(s)
| | - Satenig Guler
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Brendan Chen
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Neil Bifulco
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Hoan Huynh
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Sushmita Lahiri
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Adam B Shapiro
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Sarah M McLeod
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Nicole M Carter
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Samir H Moussa
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Camilo Velez-Vega
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Nelson B Olivier
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Ning Gao
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Jason Thresher
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Tiffany Palmer
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Beth Andrews
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - Joseph V Newman
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - David E Ehmann
- AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | | | - John O'Donnell
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - John P Mueller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Rubén A Tommasi
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
| | - Alita A Miller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA
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14
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Abstract
INTRODUCTION By virtue of its specificity for chemokines induced in Th1-associated pathologies, CXCR3 has attracted considerable attention as a target for therapeutic intervention. Several pharmacologically distinct small molecules with in vitro and in vivo potency have been described in the literature, although to date, none have shown efficacy in clinical trials. Areas covered: In this article, the author outlines the rationale for targeting CXCR3 and discusses the potential pitfalls in targeting receptors in poorly understood areas of chemokine biology. Furthermore, they cover emerging therapeutic areas outside of the 'traditional' Th1 arena in which CXCR3 antagonists may ultimately bear fruit. Finally, they discuss the design of recently discovered small molecules targeting CXCR3. Expert opinion: CXCR3 and its ligands appear to play roles in a multitude of diverse diseases in humans. In vitro studies suggest that CXCR3 is inherently 'druggable' and that potent, efficacious small molecules targeting CXCR3 antagonists will find a clinical niche. However, the well-trodden path to failure of small molecule chemokine receptor antagonists in clinical trials suggests that a cautious approach should be undertaken. Ideally, unequivocal evidence elucidating the precise role of CXCR3 should be obtained before targeting the receptor in a particular disease cohort.
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Affiliation(s)
- James E Pease
- a Inflammation, Repair & Development Section, National Heart & Lung Institute, Faculty of Medicine , Imperial College London , London , UK
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15
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16
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Du L, Suo S, Zhang H, Jia H, Liu KJ, Zhang XJ, Liu Y. The alternative strategy for designing covalent drugs through kinetic effects of pi-stacking on the self-assembled nanoparticles: a model study with antibiotics. NANOTECHNOLOGY 2016; 27:445101. [PMID: 27673346 DOI: 10.1088/0957-4484/27/44/445101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
It is still a huge challenge to find a new strategy for rationally designing covalent drugs because most of them are discovered by serendipity. Considering that the effect of covalent drugs is closely associated with the kinetics of the reaction between drug molecule and its target protein, here we first demonstrate an example of the kinetic effect of pi-stacking of drug molecules on covalent antimicrobial drug design. When PEGylated 7-aminocephalosporanic acid (PEG-ACA) is used as a substrate drug, pi-stacking of the ACA group via the self-assembly of PEG-ACA on the surface of gold nanoparticles (i.e. Au@ACA) exhibits antibacterial activity against E. coli fourfold higher than a PEG-ACA monomer does. The reason can be reasonably attributed to the kinetic rate enhancement for the covalent reaction between Au@ACA and penicillin binding proteins. We believe that the self-assembly of functional groups onto the surface of gold nanoparticles represents a new strategy for covalent drug design.
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Affiliation(s)
- Libo Du
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Science, Zhongguancun North First Street 2,100190 Beijing, People's Republic of China
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17
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Shapiro AB. Investigation of β-lactam antibacterial drugs, β-lactamases, and penicillin-binding proteins with fluorescence polarization and anisotropy: a review. Methods Appl Fluoresc 2016; 4:024002. [DOI: 10.1088/2050-6120/4/2/024002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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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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19
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June CM, Vaughan RM, Ulberg LS, Bonomo RA, Witucki LA, Leonard DA. A fluorescent carbapenem for structure function studies of penicillin-binding proteins, β-lactamases, and β-lactam sensors. Anal Biochem 2014; 463:70-4. [PMID: 25058926 DOI: 10.1016/j.ab.2014.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 07/12/2014] [Indexed: 11/29/2022]
Abstract
By reacting fluorescein isothiocyanate with meropenem, we have prepared a carbapenem-based fluorescent β-lactam. Fluorescein-meropenem binds both penicillin-binding proteins and β-lactam sensors and undergoes a typical acylation reaction in the active site of these proteins. The probe binds the class D carbapenemase OXA-24/40 with close to the same affinity as meropenem and undergoes a complete catalytic hydrolysis reaction. The visible light excitation and strong emission of fluorescein render this molecule a useful structure-function probe through its application in sodium dodecyl sulfate-polyacrylamide gel electrophoresis assays as well as solution-based kinetic anisotropy assays. Its classification as a carbapenem β-lactam and the position of its fluorescent modification render it a useful complement to other fluorescent β-lactams, most notably Bocillin FL. In this study, we show the utility of fluorescein-meropenem by using it to detect mutants of OXA-24/40 that arrest at the acyl-intermediate state with carbapenem substrates but maintain catalytic competency with penicillin substrates.
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Affiliation(s)
- Cynthia M June
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA
| | - Robert M Vaughan
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA
| | - Lucas S Ulberg
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA
| | - Robert A Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and Department of Pharmacology, Molecular Biology, and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Laurie A Witucki
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA
| | - David A Leonard
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA.
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20
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Early insights into the interactions of different β-lactam antibiotics and β-lactamase inhibitors against soluble forms of Acinetobacter baumannii PBP1a and Acinetobacter sp. PBP3. Antimicrob Agents Chemother 2012; 56:5687-92. [PMID: 22908165 DOI: 10.1128/aac.01027-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Acinetobacter baumannii is an increasingly problematic pathogen in United States hospitals. Antibiotics that can treat A. baumannii are becoming more limited. Little is known about the contributions of penicillin binding proteins (PBPs), the target of β-lactam antibiotics, to β-lactam-sulbactam susceptibility and β-lactam resistance in A. baumannii. Decreased expression of PBPs as well as loss of binding of β-lactams to PBPs was previously shown to promote β-lactam resistance in A. baumannii. Using an in vitro assay with a reporter β-lactam, Bocillin, we determined that the 50% inhibitory concentrations (IC(50)s) for PBP1a from A. baumannii and PBP3 from Acinetobacter sp. ranged from 1 to 5 μM for a series of β-lactams. In contrast, PBP3 demonstrated a narrower range of IC(50)s against β-lactamase inhibitors than PBP1a (ranges, 4 to 5 versus 8 to 144 μM, respectively). A molecular model with ampicillin and sulbactam positioned in the active site of PBP3 reveals that both compounds interact similarly with residues Thr526, Thr528, and Ser390. Accepting that many interactions with cell wall targets are possible with the ampicillin-sulbactam combination, the low IC(50)s of ampicillin and sulbactam for PBP3 may contribute to understanding why this combination is effective against A. baumannii. Unraveling the contribution of PBPs to β-lactam susceptibility and resistance brings us one step closer to identifying which PBPs are the best targets for novel β-lactams.
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21
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Kastrinsky DB, Barry CE. Synthesis of labeled meropenem for the analysis of M. tuberculosis transpeptidases. Tetrahedron Lett 2010; 51:197-200. [PMID: 20161438 DOI: 10.1016/j.tetlet.2009.10.124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A concise synthesis of (14)C labeled meropenem prepared from (14)C dimethylamine hydrochloride is described. Using a similar reaction sequence, the meropenem nucleus was also attached to biotin providing a probe for protein interaction studies.
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Affiliation(s)
- David B Kastrinsky
- The National Institutes of Health, National Institute of Allergy and Infectous Diseases, Tuberculosis Research Section, Bethesda MD 20892
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22
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Schneider KD, Bethel CR, Distler AM, Hujer AM, Bonomo RA, Leonard DA. Mutation of the active site carboxy-lysine (K70) of OXA-1 beta-lactamase results in a deacylation-deficient enzyme. Biochemistry 2009; 48:6136-45. [PMID: 19485421 DOI: 10.1021/bi900448u] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Class D beta-lactamases hydrolyze beta-lactam antibiotics by using an active site serine nucleophile to form a covalent acyl-enzyme intermediate and subsequently employ water to deacylate the beta-lactam and release product. Class D beta-lactamases are carboxylated on the epsilon-amino group of an active site lysine, with the resulting carbamate functional group serving as a general base. We discovered that substitutions of the active site serine and lysine in OXA-1 beta-lactamase, a monomeric class D enzyme, significantly disrupt catalytic turnover. Substitution of glycine for the nucleophilic serine (S67G) results in an enzyme that can still bind substrate but is unable to form a covalent acyl-enzyme intermediate. Substitution of the carboxylated lysine (K70), on the other hand, results in enzyme that can be acylated by substrate but is impaired with respect to deacylation. We employed the fluorescent penicillin BOCILLIN FL to show that three different substitutions for K70 (alanine, aspartate, and glutamate) lead to the accumulation of significant acyl-enzyme intermediate. Interestingly, BOCILLIN FL deacylation rates (t(1/2)) vary depending on the identity of the substituting residue, from approximately 60 min for K70A to undetectable deacylation for K70D. Tryptophan fluorescence spectroscopy was used to confirm that these results are applicable to natural (i.e., nonfluorescent) substrates. Deacylation by K70A, but not K70D or K70E, can be partially restored by the addition of short-chain carboxylic acid mimetics of the lysine carbamate. In conclusion, we establish the functional role of the carboxylated lysine in OXA-1 and highlight its specific role in acylation and deacylation.
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Affiliation(s)
- Kyle D Schneider
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, USA
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23
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Endimiani A, Perez F, Bonomo RA. Cefepime: a reappraisal in an era of increasing antimicrobial resistance. Expert Rev Anti Infect Ther 2008; 6:805-24. [PMID: 19053894 PMCID: PMC2633657 DOI: 10.1586/14787210.6.6.805] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cefepime is a 'fourth-generation' cephalosporin with an in vitro extended-spectrum of activity against Gram-negative and Gram-positive pathogens. Cefepime is approved for the treatment of moderate-to-severe infections, such as pneumonia, uncomplicated and complicated urinary tract infections, skin and soft-tissue infections, intra-abdominal infections and febrile neutropenia. In this article, we provide a critical review of pharmacodynamics, clinical management, pharmacokinetics, metabolism, pharmacodynamic target analyses, clinical efficacy, safety and tolerability of cefepime after more than a decade of clinical use.
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Affiliation(s)
- Andrea Endimiani
- Department of Medicine, Section of Infectious Diseases, Case Western Reserve University, School of Medicine, Cleveland, OH, USA.
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24
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Sauvage E, Kerff F, Terrak M, Ayala JA, Charlier P. The penicillin-binding proteins: structure and role in peptidoglycan biosynthesis. FEMS Microbiol Rev 2008; 32:234-58. [PMID: 18266856 DOI: 10.1111/j.1574-6976.2008.00105.x] [Citation(s) in RCA: 860] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Eric Sauvage
- Centre d'Ingénierie des Protéines, Institut de Physique B5a et Institut de Chimie B6a, University of Liège, Sart Tilman, Belgium.
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25
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Zapun A, Contreras-Martel C, Vernet T. Penicillin-binding proteins and beta-lactam resistance. FEMS Microbiol Rev 2008; 32:361-85. [PMID: 18248419 DOI: 10.1111/j.1574-6976.2007.00095.x] [Citation(s) in RCA: 386] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A number of ways and means have evolved to provide resistance to eubacteria challenged by beta-lactams. This review is focused on pathogens that resist by expressing low-affinity targets for these antibiotics, the penicillin-binding proteins (PBPs). Even within this narrow focus, a great variety of strategies have been uncovered such as the acquisition of an additional low-affinity PBP, the overexpression of an endogenous low-affinity PBP, the alteration of endogenous PBPs by point mutations or homologous recombination or a combination of the above.
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Affiliation(s)
- André Zapun
- Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, UMR 5075-CNRS, CEA, Université Joseph Fourier, Grenoble, France
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26
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Fan X, Liu Y, Smith D, Konermann L, Siu KWM, Golemi-Kotra D. Diversity of penicillin-binding proteins. Resistance factor FmtA of Staphylococcus aureus. J Biol Chem 2007; 282:35143-52. [PMID: 17925392 DOI: 10.1074/jbc.m706296200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antibiotic-resistant Staphylococcus aureus is a major concern to public health. Methicillin-resistant S. aureus strains are completely resistant to all beta-lactams antibiotics. One of the main factors involved in methicillin resistance in S. aureus is the penicillin-binding protein, PBP2a. This protein is insensitive to inactivation by beta-lactam antibiotics such as methicillin. Although other proteins are implicated in high and homogeneous levels of methicillin resistance, the functions of these other proteins remain elusive. Herein, we report for the first time on the putative function of one of these proteins, FmtA. This protein specifically interacts with beta-lactam antibiotics forming covalently bound complexes. The serine residue present in the sequence motif Ser-X-X-Lys (which is conserved among penicillin-binding proteins and beta-lactamases) is the active-site nucleophile during the formation of acyl-enzyme species. FmtA has a low binding affinity for beta-lactams, and it experiences a slow acylation rate, suggesting that this protein is intrinsically resistant to beta-lactam inactivation. We found that FmtA undergoes conformational changes in presence of beta-lactams that may be essential to the beta-lactam resistance mechanism. FmtA binds to peptidoglycan in vitro. Our findings suggest that FmtA is a penicillin-binding protein, and as such, it may compensate for suppressed peptidoglycan biosynthesis under beta-lactam induced cell wall stress conditions.
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Affiliation(s)
- Xin Fan
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
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27
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Fuda C, Hesek D, Lee M, Heilmayer W, Novak R, Vakulenko SB, Mobashery S. Mechanistic Basis for the Action of New Cephalosporin Antibiotics Effective against Methicillin- and Vancomycin-resistant Staphylococcus aureus. J Biol Chem 2006; 281:10035-41. [PMID: 16459335 DOI: 10.1074/jbc.m508846200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Emergence of methicillin-resistant Staphylococcus aureus (MRSA) has created challenges in treatment of nosocomial infections. The recent clinical emergence of vancomycin-resistant MRSA is a new disconcerting chapter in the evolution of these strains. S. aureus normally produces four PBPs, which are susceptible to modification by beta-lactam antibiotics, an event that leads to bacterial death. The gene product of mecA from MRSA is a penicillin-binding protein (PBP) designated PBP 2a. PBP 2a is refractory to the action of all commercially available beta-lactam antibiotics. Furthermore, PBP 2a is capable of taking over the functions of the other PBPs of S. aureus in the face of the challenge by beta-lactam antibiotics. Three cephalosporins (compounds 1-3) have been studied herein, which show antibacterial activities against MRSA, including the clinically important vancomycin-resistant strains. These cephalosporins exhibit substantially smaller dissociation constants for the preacylation complex compared with the case of typical cephalosporins, but their pseudo-second-order rate constants for encounter with PBP 2a (k(2)/K(s)) are not very large (< or =200 m(-1) s(-1)). It is documented herein that these cephalosporins facilitate a conformational change in PBP 2a, a process that is enhanced in the presence of a synthetic surrogate for cell wall, resulting in increases in the k(2)/K(s) parameter and in more facile enzyme inhibition. These findings argue that the novel cephalosporins are able to co-opt interactions between PBP 2a and the cell wall in gaining access to the active site in the inhibition process, a set of events that leads to effective inhibition of PBP 2a and the attendant killing of the MRSA strains.
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Affiliation(s)
- Cosimo Fuda
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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