1
|
Boostrom I, Bala Y, Vasic JM, Gluvakov J, Chanard E, Barratt AH, Sands K, Portal E, Devigne L, Jones LC, Spiller OB. Evaluation of the MYCOPLASMA IST3 urogenital mycoplasma assay in an international multicentre trial. J Antimicrob Chemother 2021; 76:3175-3182. [PMID: 34477840 PMCID: PMC8678932 DOI: 10.1093/jac/dkab320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 08/04/2021] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To evaluate the accuracy, susceptibility and specificity of MYCOPLASMA IST3, the next generation of the most popular culture-based in vitro diagnostic device designed to detect, identify and test the susceptibility of urogenital mycoplasma infections. METHODS MYCOPLASMA IST3 was evaluated against culture- and molecular-based gold standard methodologies to detect, identify, enumerate and determine antimicrobial resistance for Mycoplasma hominis and Ureaplasma species in 516 clinical samples collected across France, Serbia and the UK. Sample types included vulvovaginal/endocervical or urethral swabs (dry swab or eSwab®), semen and urine samples, which included blinded analysis following addition of a panel of 80 characterized control strains. RESULTS Overall species identification was excellent for both Ureaplasma spp. (98.4% sensitivity, 99.7% specificity) and M. hominis (95.7% sensitivity, 100% specificity) relative to combined colony morphology on agar and quantitative PCR standards. Non-dilution-based bacterial load estimation by the assay was accurate between 83.7% (M. hominis) and 86.3% (Ureaplasma spp.) of the time (increased to 94.2% and 100%, respectively, if ±10-fold variance was allowed) relative to colonies counted on agar. Resistance accuracy for Ureaplasma spp. varied from gold standards for only 11/605 of individual tests (major error rate = 1.8%) and for 14/917 individual tests for M. hominis (major error rate = 1.5%). CONCLUSIONS The redesigned MYCOPLASMA IST3 assay eliminated previous shortcomings by providing independent accurate resistance screening of M. hominis and Ureaplasma species, even in mixed infections, with CLSI-compliant thresholds. Specificity, sensitivity and enumeration estimates correlated closely with the confirmatory methods.
Collapse
Affiliation(s)
- Ian Boostrom
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK
| | - Yohan Bala
- bioMérieux Global Clinical Affairs, Marcy, L'Étoile, France
| | | | | | | | - Andrew H Barratt
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK
| | - Kirsty Sands
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK.,Department of Zoology, University of Oxford, Oxford, UK
| | - Edward Portal
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK
| | | | - Lucy C Jones
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK.,Department of Integrated Sexual Health, Dewi Sant Hospital Cwm Taf Morgannwg University Health Board, Pontypridd, UK.,HealthFirst Consulting, Research Division, Blackwood, UK
| | - Owen B Spiller
- Cardiff University, Division of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff, UK.,Public Heath England, Bacterial Reference Department, London, UK
| |
Collapse
|
2
|
Salehi N, Attaran B, Zare-Mirakabad F, Ghadiri B, Esmaeili M, Shakaram M, Tashakoripour M, Eshagh Hosseini M, Mohammadi M. The outward shift of clarithromycin binding to the ribosome in mutant Helicobacter pylori strains. Helicobacter 2020; 25:e12731. [PMID: 32794288 DOI: 10.1111/hel.12731] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/30/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023]
Abstract
OBJECTIVES Disruption of protein synthesis, by drug-mediated restriction of the ribosomal nascent peptide exit tunnel (NPET), may inhibit bacterial growth. Here, we have studied the secondary and tertiary structures of domain V of the 23S rRNA in the wild-type and mutant (resistant) H. pylori strains and their mechanisms of interaction with clarithromycin (CLA). METHODS H pylori strains, isolated from cultured gastric biopsies, underwent CLA susceptibility testing by E test, followed by PCR amplification and sequencing of domain V of 23S rRNA. The homology model of this domain in H pylori, in complex with L4 and L22 accessory proteins, was determined based on the E. coli ribosome 3D structure. The interactions between CLA and 23S rRNA complex were determined by molecular docking studies. RESULTS Of the 70 H pylori strains, isolated from 200 dyspeptic patients, 11 (16%) were CLA-resistant. DNA sequencing identified categories with no (A), A2142G (B), and A2143G (C) mutations. Docking studies of our homology model of 23S rRNA complex with CLA showed deviated positions for categories B and C, in reference to category A, with 12.19 Å and 7.92 Å RMSD values, respectively. In both mutant categories, CLA lost its interactions at positions 2142 and 2587 and gained two new bonds with the L4 accessory protein. CONCLUSION Our data suggest that, in mutant H pylori strains, once the nucleotides at positions 2142 and 2587 are detached from the drug, CLA interacts with and is peeled back by the L4 accessory protein, removing the drug-imposed spatial restriction of the NPET.
Collapse
Affiliation(s)
- Najmeh Salehi
- Department of Bioinformatics, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Bahareh Attaran
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.,Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Fatemeh Zare-Mirakabad
- Department of Mathematics and Computer Science, Amirkabir University of Technology, Tehran, Iran
| | - Bahareh Ghadiri
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Maryam Esmaeili
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohadeseh Shakaram
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Tashakoripour
- Gastroenterology Department, Amiralam Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmoud Eshagh Hosseini
- Gastroenterology Department, Amiralam Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Marjan Mohammadi
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| |
Collapse
|
3
|
Davoodi S, Daryaee F, Chang A, Walker SG, Tonge PJ. Correlating Drug-Target Residence Time and Post-antibiotic Effect: Insight into Target Vulnerability. ACS Infect Dis 2020; 6:629-636. [PMID: 32011855 DOI: 10.1021/acsinfecdis.9b00484] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Target vulnerability correlates the level of drug-target engagement required to generate a pharmacological response. High vulnerability targets are those that require only a relatively small fraction of occupancy to achieve the desired pharmacological outcome, whereas low vulnerability targets require high levels of engagement. Here, we demonstrate that the slope of the correlation between drug-target residence time and the post-antibiotic effect (PAE) can be used to define the vulnerability of bacterial targets. For macrolides, a steep slope is observed between residence time on the E. coli ribosome and the PAE, indicating that the ribosome is a highly vulnerable drug target. The analysis of the residence time-PAE data for erythromycin, azithromycin, spiramycin, and telithromycin using a mechanistic pharmacokinetic-pharmacodynamic model that integrates drug-target kinetics into predictions of drug activity lead to the successful prediction of the cellular PAE for tylosin, which has the longest residence time (7.1 h) and PAE (5.8 h). Although the macrolide data support a connection between residence time, PAE, and bactericidality, many bactericidal β-lactam antibiotics do not give a PAE, illustrating the role of factors such as protein resynthesis in the expression of target vulnerability.
Collapse
|
4
|
A long-distance rRNA base pair impacts the ability of macrolide antibiotics to kill bacteria. Proc Natl Acad Sci U S A 2020; 117:1971-1975. [PMID: 31932436 PMCID: PMC6995004 DOI: 10.1073/pnas.1918948117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bactericidal activity of macrolide antibiotics correlates with the presence of an extended alkyl-aryl side chain, which accounts for their slow departure rate from the ribosome. Here, we found that the base pair between 23S ribosomal RNA (rRNA) nucleotides 752 and 2609 located in the macrolide binding site is important for the ribosome functionality and for establishing the unique interactions with the extended side chain of macrolide antibiotics. Disruption of the 752-2609 base pair accelerates the departure of extended macrolides from the ribosome and reduces their cidality. Our results demonstrate that not only the chemical features of the antibiotic, but also the structure of the target site contribute to the ability of the inhibitor to kill bacteria. While most of the ribosome-targeting antibiotics are bacteriostatic, some members of the macrolide class demonstrate considerable bactericidal activity. We previously showed that an extended alkyl-aryl side chain is the key structural element determining the macrolides’ slow dissociation from the ribosome and likely accounts for the antibiotics’ cidality. In the nontranslating Escherichia coli ribosome, the extended side chain of macrolides interacts with 23S ribosomal RNA (rRNA) nucleotides A752 and U2609, that were proposed to form a base pair. However, the existence of this base pair in the translating ribosome, its possible functional role, and its impact on the binding and cidality of the antibiotic remain unknown. By engineering E. coli cells carrying individual and compensatory mutations at the 752 and 2609 rRNA positions, we show that integrity of the base pair helps to modulate the ribosomal response to regulatory nascent peptides, determines the slow dissociation rate of the extended macrolides from the ribosome, and increases their bactericidal effect. Our findings demonstrate that the ability of antibiotics to kill bacterial cells relies not only on the chemical nature of the inhibitor, but also on structural features of the target.
Collapse
|
5
|
Kinetics of drug-ribosome interactions defines the cidality of macrolide antibiotics. Proc Natl Acad Sci U S A 2017; 114:13673-13678. [PMID: 29229833 DOI: 10.1073/pnas.1717168115] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Antibiotics can cause dormancy (bacteriostasis) or induce death (cidality) of the targeted bacteria. The bactericidal capacity is one of the most important properties of antibacterial agents. However, the understanding of the fundamental differences in the mode of action of bacteriostatic or bactericidal antibiotics, especially those belonging to the same chemical class, is very rudimentary. Here, by examining the activity and binding properties of chemically distinct macrolide inhibitors of translation, we have identified a key difference in their interaction with the ribosome, which correlates with their ability to cause cell death. While bacteriostatic and bactericidal macrolides bind in the nascent peptide exit tunnel of the large ribosomal subunit with comparable affinities, the bactericidal antibiotics dissociate from the ribosome with significantly slower rates. The sluggish dissociation of bactericidal macrolides correlates with the presence in their structure of an extended alkyl-aryl side chain, which establishes idiosyncratic interactions with the ribosomal RNA. Mutations or chemical alterations of the rRNA nucleotides in the drug binding site can protect cells from macrolide-induced killing, even with inhibitor concentrations that significantly exceed those required for cell growth arrest. We propose that the increased translation downtime due to slow dissociation of the antibiotic may damage cells beyond the point where growth can be reinitiated upon the removal of the drug due to depletion of critical components of the gene-expression pathway.
Collapse
|
6
|
Pavlova A, Gumbart JC. Parametrization of macrolide antibiotics using the force field toolkit. J Comput Chem 2015; 36:2052-63. [PMID: 26280362 DOI: 10.1002/jcc.24043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/25/2015] [Accepted: 07/03/2015] [Indexed: 01/09/2023]
Abstract
Macrolides are an important class of antibiotics that target the bacterial ribosome. Computer simulations of macrolides are limited as specific force field parameters have not been previously developed for them. Here, we determine CHARMM-compatible force field parameters for erythromycin, azithromycin, and telithromycin, using the force field toolkit (ffTK) plugin in VMD. Because of their large size, novel approaches for parametrizing them had to be developed. Two methods for determining partial atomic charges, from interactions with TIP3P water and from the electrostatic potential, as well as several approaches for fitting the dihedral parameters were tested. The performance of the different parameter sets was evaluated by molecular dynamics simulations of the macrolides in ribosome, with a distinct improvement in maintenance of key interactions observed after refinement of the initial parameters. Based on the results of the macrolide tests, recommended procedures for parametrizing very large molecules using ffTK are given.
Collapse
Affiliation(s)
- Anna Pavlova
- School of Physics and School of Chemistry, Georgia Institute of Technology, Atlanta, 30332, Georgia
| | - James C Gumbart
- School of Physics and School of Chemistry, Georgia Institute of Technology, Atlanta, 30332, Georgia
| |
Collapse
|
7
|
Kostopoulou ON, Magoulas GE, Papadopoulos GE, Mouzaki A, Dinos GP, Papaioannou D, Kalpaxis DL. Synthesis and evaluation of chloramphenicol homodimers: molecular target, antimicrobial activity, and toxicity against human cells. PLoS One 2015; 10:e0134526. [PMID: 26267355 PMCID: PMC4533973 DOI: 10.1371/journal.pone.0134526] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/09/2015] [Indexed: 12/05/2022] Open
Abstract
As fight against antibiotic resistance must be strengthened, improving old drugs that have fallen in reduced clinical use because of toxic side effects and/or frequently reported resistance, like chloramphenicol (CAM), is of special interest. Chloramphenicol (CAM), a prototypical wide-spectrum antibiotic has been shown to obstruct protein synthesis via binding to the bacterial ribosome. In this study we sought to identify features intensifying the bacteriostatic action of CAM. Accordingly, we synthesized a series of CAM-dimers with various linker lengths and functionalities and compared their efficiency in inhibiting peptide-bond formation in an Escherichia coli cell-free system. Several CAM-dimers exhibited higher activity, when compared to CAM. The most potent of them, compound 5, containing two CAM bases conjugated via a dicarboxyl aromatic linker of six successive carbon-bonds, was found to simultaneously bind both the ribosomal catalytic center and the exit-tunnel, thus revealing a second, kinetically cryptic binding site for CAM. Compared to CAM, compound 5 exhibited comparable antibacterial activity against MRSA or wild-type strains of Staphylococcus aureus, Enterococcus faecium and E. coli, but intriguingly superior activity against some CAM-resistant E. coli and Pseudomonas aeruginosa strains. Furthermore, it was almost twice as active in inhibiting the growth of T-leukemic cells, without affecting the viability of normal human lymphocytes. The observed effects were rationalized by footprinting tests, crosslinking analysis, and MD-simulations.
Collapse
Affiliation(s)
| | - George E. Magoulas
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, Patras, Greece
| | - Georgios E. Papadopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos, Larissa, Greece
| | - Athanasia Mouzaki
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, Patras, Greece
| | - George P. Dinos
- Department of Biochemistry, School of Medicine, University of Patras, Patras, Greece
| | - Dionissios Papaioannou
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, Patras, Greece
- * E-mail:
| | - Dimitrios L. Kalpaxis
- Department of Biochemistry, School of Medicine, University of Patras, Patras, Greece
- * E-mail:
| |
Collapse
|
8
|
Krokidis M, Bougas A, Stavropoulou M, Kalpaxis D, Dinos GP. The slow dissociation rate of K-1602 contributes to the enhanced inhibitory activity of this novel alkyl-aryl-bearing fluoroketolide. J Enzyme Inhib Med Chem 2015; 31:276-82. [PMID: 25807301 DOI: 10.3109/14756366.2015.1018246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ketolides belong to the latest generation of macrolides and are not only effective against macrolide susceptible bacterial strains but also against some macrolide resistant strains. Here we present data providing insights into the mechanism of action of K-1602, a novel alkyl-aryl-bearing fluoroketolide. According to our data, the K-1602 interacts with the ribosome as a one-step slow binding inhibitor, displaying an association rate constant equal to 0.28 × 10(4) M(-1) s(-1) and a dissociation rate constant equal to 0.0025 min(-1). Both constants contribute to produce an overall inhibition constant Ki equal to 1.49 × 10(-8) M, which correlates very well with the superior activity of this compound when compared with many other ketolides or fluoroketolides.
Collapse
Affiliation(s)
- Marios Krokidis
- a Department of Pharmacology , Medical School, University of Athens , Athens , Greece
| | - Anthony Bougas
- b Laboratory of Biochemistry , School of Medicine, University of Patras , Patras , Greece , and
| | - Maria Stavropoulou
- c Department of Chemistry , Technical University of Munich , Munich , Germany
| | - Dimitrios Kalpaxis
- b Laboratory of Biochemistry , School of Medicine, University of Patras , Patras , Greece , and
| | - George P Dinos
- b Laboratory of Biochemistry , School of Medicine, University of Patras , Patras , Greece , and
| |
Collapse
|
9
|
Kostopoulou ON, Kouvela EC, Magoulas GE, Garnelis T, Panagoulias I, Rodi M, Papadopoulos G, Mouzaki A, Dinos GP, Papaioannou D, Kalpaxis DL. Conjugation with polyamines enhances the antibacterial and anticancer activity of chloramphenicol. Nucleic Acids Res 2014; 42:8621-34. [PMID: 24939899 PMCID: PMC4117768 DOI: 10.1093/nar/gku539] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Chloramphenicol (CAM) is a broad-spectrum antibiotic, limited to occasional only use in developed countries because of its potential toxicity. To explore the influence of polyamines on the uptake and activity of CAM into cells, a series of polyamine–CAM conjugates were synthesized. Both polyamine architecture and the position of CAM-scaffold substitution were crucial in augmenting the antibacterial and anticancer potency of the synthesized conjugates. Compounds 4 and 5, prepared by replacement of dichloro-acetyl group of CAM with succinic acid attached to N4 and N1 positions of N8,N8-dibenzylspermidine, respectively, exhibited higher activity than CAM in inhibiting the puromycin reaction in a bacterial cell-free system. Kinetic and footprinting analysis revealed that whereas the CAM-scaffold preserved its role in competing with the binding of aminoacyl-tRNA 3′-terminus to ribosomal A-site, the polyamine-tail could interfere with the rotatory motion of aminoacyl-tRNA 3′-terminus toward the P-site. Compared to CAM, compounds 4 and 5 exhibited comparable or improved antibacterial activity, particularly against CAM-resistant strains. Compound 4 also possessed enhanced toxicity against human cancer cells, and lower toxicity against healthy human cells. Thus, the designed conjugates proved to be suitable tools in investigating the ribosomal catalytic center plasticity and some of them exhibited greater efficacy than CAM itself.
Collapse
Affiliation(s)
- Ourania N Kostopoulou
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Ekaterini C Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - George E Magoulas
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Thomas Garnelis
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Ioannis Panagoulias
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - Maria Rodi
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - Georgios Papadopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos 26, GR-41221 Larissa, Greece
| | - Athanasia Mouzaki
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - George P Dinos
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Dionissios Papaioannou
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Dimitrios L Kalpaxis
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| |
Collapse
|
10
|
Jensen JS, Fernandes P, Unemo M. In vitro activity of the new fluoroketolide solithromycin (CEM-101) against macrolide-resistant and -susceptible Mycoplasma genitalium strains. Antimicrob Agents Chemother 2014; 58:3151-6. [PMID: 24637681 PMCID: PMC4068426 DOI: 10.1128/aac.02411-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 03/12/2014] [Indexed: 11/20/2022] Open
Abstract
Mycoplasma genitalium has become well established as an etiological agent of sexually transmitted infections, but due to its fastidious growth requirements, only a few M. genitalium strains are available to determine the MICs of currently used and new antimicrobial agents. Recent clinical trials have suggested that treatment with azithromycin has decreasing efficacy due to an increasing prevalence of macrolide resistance, and alternative treatment with moxifloxacin is similarly under pressure from emerging resistance. Thus, there is an urgent need for new antimicrobials. The in vitro activity of the newly developed fluoroketolide solithromycin (CEM-101) was evaluated against a collection of 40 M. genitalium strains, including 15 with high-level macrolide resistance and 5 multidrug-resistant strains with resistance to both macrolides and quinolones. Furthermore, the MIC of solithromycin was correlated with mutations in the 23S rRNA gene and in the genes encoding ribosomal proteins L4 and L22. The in vitro results showed that solithromycin has activity against M. genitalium superior to that of other macrolides, doxycycline, and fluoroquinolones. Accordingly, this new fluoroketolide might be an effective option for treatment of M. genitalium infections. However, the efficacy of solithromycin in clinical trials with follow-up for test of cure and detection of genotypic and phenotypic resistance needs to be evaluated prior to widespread use. In a phase 2 clinical trial, solithromycin was highly effective as a single oral dose against C. trachomatis and Neisseria gonorrhoeae, suggesting that solithromycin could be a treatment option for several sexually transmitted infections, including in syndromic treatment of urethral and vaginal discharge.
Collapse
Affiliation(s)
- Jørgen Skov Jensen
- Microbiology and Infection Control, Sexually Transmitted Bacterial Infections, Research and Development, Statens Serum Institut, Copenhagen, Denmark
| | | | - Magnus Unemo
- WHO Collaborating Centre for Gonorrhoea and other STIs, Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden
| |
Collapse
|
11
|
Insights into the mode of action of novel fluoroketolides, potent inhibitors of bacterial protein synthesis. Antimicrob Agents Chemother 2013; 58:472-80. [PMID: 24189263 DOI: 10.1128/aac.01994-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ketolides, the third generation of expanded-spectrum macrolides, have in the last years become a successful weapon in the endless war against macrolide-resistant pathogens. Ketolides are semisynthetic derivatives of the naturally produced macrolide erythromycin, displaying not only improved activity against some erythromycin-resistant strains but also increased bactericidal activity as well as inhibitory effects at lower drug concentrations. In this study, we present a series of novel ketolides carrying alkyl-aryl side chains at the C-6 position of the lactone ring and, additionally, one or two fluorine atoms attached either directly to the lactone ring at the C-2 position or indirectly via the C-13 position. According to our genetic and biochemical studies, these novel ketolides occupy the known macrolide binding site at the entrance of the ribosomal tunnel and exhibit lower MIC values against wild-type or mutant strains than erythromycin. In most cases, the ketolides display activities comparable to or better than the clinically used ketolide telithromycin. Chemical protection experiments using Escherichia coli ribosomes bearing U2609C or U754A mutations in 23S rRNA suggest that the alkyl-aryl side chain establishes an interaction with the U2609-A752 base pair, analogous to that observed with telithromycin but unlike the interactions formed by cethromycin. These findings reemphasize the versatility of the alkyl-aryl side chains with respect to species specificity, which will be important for future design of improved antimicrobial agents.
Collapse
|
12
|
Small MC, Lopes P, Andrade RB, MacKerell AD. Impact of ribosomal modification on the binding of the antibiotic telithromycin using a combined grand canonical monte carlo/molecular dynamics simulation approach. PLoS Comput Biol 2013; 9:e1003113. [PMID: 23785274 PMCID: PMC3681621 DOI: 10.1371/journal.pcbi.1003113] [Citation(s) in RCA: 16] [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: 02/25/2013] [Accepted: 05/07/2013] [Indexed: 02/05/2023] Open
Abstract
Resistance to macrolide antibiotics is conferred by mutation of A2058 to G or methylation by Erm methyltransferases of the exocyclic N6 of A2058 (E. coli numbering) that forms the macrolide binding site in the 50S subunit of the ribosome. Ketolides such as telithromycin mitigate A2058G resistance yet remain susceptible to Erm-based resistance. Molecular details associated with macrolide resistance due to the A2058G mutation and methylation at N6 of A2058 by Erm methyltransferases were investigated using empirical force field-based simulations. To address the buried nature of the macrolide binding site, the number of waters within the pocket was allowed to fluctuate via the use of a Grand Canonical Monte Carlo (GCMC) methodology. The GCMC water insertion/deletion steps were alternated with Molecular Dynamics (MD) simulations to allow for relaxation of the entire system. From this GCMC/MD approach information on the interactions between telithromycin and the 50S ribosome was obtained. In the wild-type (WT) ribosome, the 2'-OH to A2058 N1 hydrogen bond samples short distances with a higher probability, while the effectiveness of telithromycin against the A2058G mutation is explained by a rearrangement of the hydrogen bonding pattern of the 2'-OH to 2058 that maintains the overall antibiotic-ribosome interactions. In both the WT and A2058G mutation there is significant flexibility in telithromycin's imidazole-pyridine side chain (ARM), indicating that entropic effects contribute to the binding affinity. Methylated ribosomes show lower sampling of short 2'-OH to 2058 distances and also demonstrate enhanced G2057-A2058 stacking leading to disrupted A752-U2609 Watson-Crick (WC) interactions as well as hydrogen bonding between telithromycin's ARM and U2609. This information will be of utility in the rational design of novel macrolide analogs with improved activity against methylated A2058 ribosomes.
Collapse
Affiliation(s)
- Meagan C. Small
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland, United States of America
| | - Pedro Lopes
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland, United States of America
| | - Rodrigo B. Andrade
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Alexander D. MacKerell
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland, United States of America
| |
Collapse
|