1
|
Dousa KM, Shin E, Kurz SG, Plummer M, Nantongo M, Bethel CR, Taracila MA, Nguyen DC, Kreiswith BN, Daley CL, Remy KE, Holland SM, Bonomo RA. Synergistic effects of sulopenem in combination with cefuroxime or durlobactam against Mycobacterium abscessus. mBio 2024; 15:e0060924. [PMID: 38742824 DOI: 10.1128/mbio.00609-24] [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: 02/28/2024] [Accepted: 03/11/2024] [Indexed: 05/16/2024] Open
Abstract
Mycobacterium abscessus (Mab) affects patients with immunosuppression or underlying structural lung diseases such as cystic fibrosis (CF). Additionally, Mab poses clinical challenges due to its resistance to multiple antibiotics. Herein, we investigated the synergistic effect of dual β-lactams [sulopenem and cefuroxime (CXM)] or the combination of sulopenem and CXM with β-lactamase inhibitors [BLIs-avibactam (AVI) or durlobactam (DUR)]. The sulopenem-CXM combination yielded low minimum inhibitory concentration (MIC) values for 54 clinical Mab isolates and ATCC19977 (MIC50 and MIC90 ≤0.25 µg/mL). Similar synergistic effects were observed in time-kill studies conducted at concentrations achievable in clinical settings. Sulopenem-CXM outperformed monotherapy, yielding ~1.5 Log10 CFU/mL reduction during 10 days. Addition of BLIs enhanced this antibacterial effect, resulting in an additional reduction of CFUs (~3 Log10 for sulopenem-CXM and AVI and ~4 Log10 for sulopenem-DUR). Exploration of the potential mechanisms of the synergy focused on their interactions with L,D-transpeptidases (Ldts; LdtMab1-LdtMab4), penicillin-binding-protein B (PBP B), and D,D-carboxypeptidase (DDC). Acyl complexes, identified via mass spectrometry analysis, demonstrated the binding of sulopenem with LdtMab2-LdtMab4, DDC, and PBP B and CXM with LdtMab2 and PBP B. Molecular docking and mass spectrometry data suggest the formation of a covalent adduct between sulopenem and LdtMab2 after the nucleophilic attack of the cysteine residue at the β-lactam carbonyl carbon, leading to the cleavage of the β-lactam ring and the establishment of a thioester bond linking the LdtMab2 with sulopenem. In conclusion, we demonstrated the biochemical basis of the synergy of sulopenem-CXM with or without BLIs. These findings potentially broaden the selection of oral therapeutic agents to combat Mab. IMPORTANCE Treating infections from Mycobacterium abscessus (Mab), particularly those resistant to common antibiotics like macrolides, is notoriously difficult, akin to a never-ending struggle for healthcare providers. The rate of treatment failure is even higher than that seen with multidrug-resistant tuberculosis. The role of combination β-lactams in inhibiting L,D-transpeptidation, the major peptidoglycan crosslink reaction in Mab, is an area of intense investigation, and clinicians have utilized this approach in the treatment of macrolide-resistant Mab, with reports showing clinical success. In our study, we found that cefuroxime and sulopenem, when used together, display a significant synergistic effect. If this promising result seen in lab settings, translates well into real-world clinical effectiveness, it could revolutionize current treatment methods. This combination could either replace the need for more complex intravenous medications or serve as a "step down" to an oral medication regimen. Such a shift would be much easier for patients to manage, enhancing their comfort and likelihood of sticking to the treatment plan, which could lead to better outcomes in tackling these tough infections. Our research delved into how these drugs inhibit cell wall synthesis, examined time-kill data and binding studies, and provided a scientific basis for the observed synergy in cell-based assays.
Collapse
Affiliation(s)
- Khalid M Dousa
- Louis Stokes Cleveland VA Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Eunjeong Shin
- Louis Stokes Cleveland VA Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Sebastian G Kurz
- Department of Medicine, University of Tübingen, Tübingen, Germany
| | - Mark Plummer
- Yale Center for Molecular Discovery, Yale University, New Haven, Connecticut, USA
| | - Mary Nantongo
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Christopher R Bethel
- Louis Stokes Cleveland VA Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Magdalena A Taracila
- Louis Stokes Cleveland VA Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - David C Nguyen
- Department of Pediatrics, Division of Pediatric Infectious Diseases and Department of Internal Medicine, Division of Infectious Diseases, Rush Medical College, Chicago, Illinois, USA
| | - Barry N Kreiswith
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Charles L Daley
- Division of Mycobacterial and Respiratory Infections, National Jewish Health, Denver, Colorado, USA
| | - Kenneth E Remy
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Steven M Holland
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert A Bonomo
- Louis Stokes Cleveland VA Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA
| |
Collapse
|
2
|
Chen L, Shashkina E, Kurepina N, Calado Nogueira de Moura V, Daley CL, Kreiswirth BN. In vitro activity of cefoxitin, imipenem, meropenem, and ceftaroline in combination with vaborbactam against Mycobacterium abscessus. Antimicrob Agents Chemother 2024; 68:e0017424. [PMID: 38557171 PMCID: PMC11064484 DOI: 10.1128/aac.00174-24] [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: 01/31/2024] [Accepted: 02/28/2024] [Indexed: 04/04/2024] Open
Abstract
Mycobacterium abscessus (MAB) infections pose a growing public health threat. Here, we assessed the in vitro activity of the boronic acid-based β-lactamase inhibitor, vaborbactam, with different β-lactams against 100 clinical MAB isolates. Enhanced activity was observed with meropenem and ceftaroline with vaborbactam (1- and >4-fold MIC50/90 reduction). CRISPRi-mediated blaMAB gene knockdown showed a fourfold MIC reduction to ceftaroline but not the other β-lactams. Our findings demonstrate vaborbactam's potential in combination therapy against MAB infections.
Collapse
Affiliation(s)
- Liang Chen
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, New Jersey, USA
| | - Elena Shashkina
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Natalia Kurepina
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | | | - Charles L. Daley
- Department of Medicine, National Jewish Health, Denver, Colorado, USA
- The University of Colorado, Aurora, Colorado, USA
| | - Barry N. Kreiswirth
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, New Jersey, USA
| |
Collapse
|
3
|
Wetzel KS, Illouz M, Abad L, Aull HG, Russell DA, Garlena RA, Cristinziano M, Malmsheimer S, Chalut C, Hatfull GF, Kremer L. Therapeutically useful mycobacteriophages BPs and Muddy require trehalose polyphleates. Nat Microbiol 2023; 8:1717-1731. [PMID: 37644325 PMCID: PMC10465359 DOI: 10.1038/s41564-023-01451-6] [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: 03/14/2023] [Accepted: 07/17/2023] [Indexed: 08/31/2023]
Abstract
Mycobacteriophages show promise as therapeutic agents for non-tuberculous mycobacterium infections. However, little is known about phage recognition of Mycobacterium cell surfaces or mechanisms of phage resistance. We show here that trehalose polyphleates (TPPs)-high-molecular-weight, surface-exposed glycolipids found in some mycobacterial species-are required for infection of Mycobacterium abscessus and Mycobacterium smegmatis by clinically useful phages BPs and Muddy. TPP loss leads to defects in adsorption and infection and confers resistance. Transposon mutagenesis shows that TPP disruption is the primary mechanism for phage resistance. Spontaneous phage resistance occurs through TPP loss by mutation, and some M. abscessus clinical isolates are naturally phage-insensitive due to TPP synthesis gene mutations. Both BPs and Muddy become TPP-independent through single amino acid substitutions in their tail spike proteins, and M. abscessus mutants resistant to TPP-independent phages reveal additional resistance mechanisms. Clinical use of BPs and Muddy TPP-independent mutants should preempt phage resistance caused by TPP loss.
Collapse
Affiliation(s)
- Katherine S Wetzel
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Morgane Illouz
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
| | - Lawrence Abad
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Haley G Aull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Daniel A Russell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rebecca A Garlena
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Madison Cristinziano
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Silke Malmsheimer
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
| | - Christian Chalut
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Laurent Kremer
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France.
- INSERM, IRIM, Montpellier, France.
| |
Collapse
|
4
|
Wetzel KS, Illouz M, Abad L, Aull HG, Russell DA, Garlena RA, Cristinziano M, Malmsheimer S, Chalut C, Hatfull GF, Kremer L. Mycobacterium trehalose polyphleates are required for infection by therapeutically useful mycobacteriophages BPs and Muddy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532567. [PMID: 36993724 PMCID: PMC10055034 DOI: 10.1101/2023.03.14.532567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mycobacteriophages are good model systems for understanding their bacterial hosts and show promise as therapeutic agents for nontuberculous mycobacterium infections. However, little is known about phage recognition of Mycobacterium cell surfaces, or mechanisms of phage resistance. We show here that surface-exposed trehalose polyphleates (TPPs) are required for infection of Mycobacterium abscessus and Mycobacterium smegmatis by clinically useful phages BPs and Muddy, and that TPP loss leads to defects in adsorption, infection, and confers resistance. Transposon mutagenesis indicates that TPP loss is the primary mechanism for phage resistance. Spontaneous phage resistance occurs through TPP loss, and some M. abscessus clinical isolates are phage-insensitive due to TPP absence. Both BPs and Muddy become TPP-independent through single amino acid substitutions in their tail spike proteins, and M. abscessus mutants resistant to TPP-independent phages reveal additional resistance mechanisms. Clinical use of BPs and Muddy TPP-independent mutants should preempt phage resistance caused by TPP loss.
Collapse
|
5
|
Finin P, Khan RMN, Oh S, Boshoff HIM, Barry CE. Chemical approaches to unraveling the biology of mycobacteria. Cell Chem Biol 2023; 30:420-435. [PMID: 37207631 PMCID: PMC10201459 DOI: 10.1016/j.chembiol.2023.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/07/2023] [Accepted: 04/27/2023] [Indexed: 05/21/2023]
Abstract
Mycobacterium tuberculosis (Mtb), perhaps more than any other organism, is intrinsically appealing to chemical biologists. Not only does the cell envelope feature one of the most complex heteropolymers found in nature1 but many of the interactions between Mtb and its primary host (we humans) rely on lipid and not protein mediators.2,3 Many of the complex lipids, glycolipids, and carbohydrates biosynthesized by the bacterium still have unknown functions, and the complexity of the pathological processes by which tuberculosis (TB) disease progress offers many opportunities for these molecules to influence the human response. Because of the importance of TB in global public health, chemical biologists have applied a wide-ranging array of techniques to better understand the disease and improve interventions.
Collapse
Affiliation(s)
- Peter Finin
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, Bethesda, MD, USA
| | - R M Naseer Khan
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, Bethesda, MD, USA
| | - Sangmi Oh
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, Bethesda, MD, USA
| | - Helena I M Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, Bethesda, MD, USA
| | - Clifton E Barry
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, Bethesda, MD, USA.
| |
Collapse
|
6
|
Gilliland HN, Beckman OK, Olive AJ. A Genome-Wide Screen in Macrophages Defines Host Genes Regulating the Uptake of Mycobacterium abscessus. mSphere 2023; 8:e0066322. [PMID: 36794958 PMCID: PMC10117111 DOI: 10.1128/msphere.00663-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/26/2023] [Indexed: 02/17/2023] Open
Abstract
The interactions between a host cell and a pathogen can dictate disease outcomes and are important targets for host-directed therapies. Mycobacterium abscessus (Mab) is a highly antibiotic resistant, rapidly growing nontuberculous mycobacterium that infects patients with chronic lung diseases. Mab can infect host immune cells, such as macrophages, which contribute to its pathogenesis. However, our understanding of initial host-Mab interactions remains unclear. Here, we developed a functional genetic approach to define these host-Mab interactions by coupling a Mab fluorescent reporter with a genome-wide knockout library in murine macrophages. We used this approach to conduct a forward genetic screen to define host genes that contribute to the uptake of Mab by macrophages. We identified known regulators of phagocytosis, such as the integrin ITGB2, and uncovered a key requirement for glycosaminoglycan (sGAG) synthesis for macrophages to efficiently take up Mab. CRISPR-Cas9 targeting of three key sGAG biosynthesis regulators, Ugdh, B3gat3, and B4galt7 resulted in reduced uptake of both smooth and rough Mab variants by macrophages. Mechanistic studies suggest that sGAGs function upstream of pathogen engulfment and are required for the uptake of Mab, but not Escherichia coli or latex beads. Further investigation found that the loss of sGAGs reduced the surface expression, but not the mRNA expression, of key integrins, suggesting an important role for sGAGs in modulating surface receptor availability. Together, these studies globally define and characterize important regulators of macrophage-Mab interactions and are a first step to understanding host genes that contribute to Mab pathogenesis and disease. IMPORTANCE Pathogen interactions with immune cells like macrophages contribute to pathogenesis, yet the mechanisms underlying these interactions remain largely undefined. For emerging respiratory pathogens, like Mycobacterium abscessus, understanding these host-pathogen interactions is important to fully understand disease progression. Given that M. abscessus is broadly recalcitrant to antibiotic treatments, new therapeutic approaches are needed. Here, we leveraged a genome-wide knockout library in murine macrophages to globally define host genes required for M. abscessus uptake. We identified new macrophage uptake regulators during M. abscessus infection, including a subset of integrins and the glycosaminoglycan synthesis (sGAG) pathway. While ionic characteristics of sGAGs are known to drive pathogen-cell interactions, we discovered a previously unrecognized requirement for sGAGs to maintain robust surface expression of key uptake receptors. Thus, we developed a flexible forward-genetic pipeline to define important interactions during M. abscessus infection and more broadly identified a new mechanism by which sGAGs control pathogen uptake.
Collapse
Affiliation(s)
- Haleigh N. Gilliland
- Department of Microbiology and Molecular Genetics, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Olivia K. Beckman
- Department of Microbiology and Molecular Genetics, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Andrew J. Olive
- Department of Microbiology and Molecular Genetics, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| |
Collapse
|
7
|
Genetic Identification of Methicillin-Resistant Staphylococcus aureus Nasal Carriage and Its Antibiogram among Kidney Dialysis Patients at a Tertiary Care Hospital in AL-Karak, Jordan. Int J Microbiol 2023; 2023:9217014. [PMID: 36970126 PMCID: PMC10033209 DOI: 10.1155/2023/9217014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/20/2023] [Accepted: 03/03/2023] [Indexed: 03/17/2023] Open
Abstract
Background. Methicillin-resistant Staphylococcus aureus (MRSA) is a major bacterial pathogen. Aim. The present study aimed to determine the incidence of MRSA infections among kidney dialysis patients and the antibiotic susceptibility patterns and investigate the prevalence of mecA gene among MRSA isolates. Materials and Methods. A total of 83 nasal sterile cotton swabs samples were obtained from hemodialysis patients from Al-Karak Governmental Hospital, Al-Karak, Jordan. Collected and cultured on nutrient agar and mannitol salt agar and incubating at 37°C for 24–48 hours, Staphylococcus aureus (S. aureus) strains were identified by gram stain, coagulase test, and catalase tests. The MRSA isolates were tested for the presence of MecA and SCCmec genes using the Xpert SA Nasal Complete assay real-time PCR. Factors such as age and gender were included in the study. The antibiotic profile tested by using the disc diffusion method tested all MRSA isolates. Results. This study showed that 10.8% of the cultures’ growth was S. aureus and 9.6% of all the patients were infected with MRSA, with no relationship between the number and frequency of MRSA according to the patient’s gender or age. All MRSA (100%) isolates have both genes (MecA genes and SCCmec genes), and all samples were resistant to oxacillin, ceftazidime, cefoxitin, aztreonam, and ampicillin. Conclusion. The MRSA prevalence was determined among kidney dialysis patients in the hospital. All positive samples were resistant to oxacillin, ceftazidime, cefoxitin, aztreonam, and ampicillin, which is a very rare finding, and this will give the scientists and doctors a dangerous indication about health-care centers in the Al-Karak city of Jordan.
Collapse
|
8
|
Sullivan MR, McGowen K, Liu Q, Akusobi C, Young DC, Mayfield JA, Raman S, Wolf ID, Moody DB, Aldrich CC, Muir A, Rubin EJ. Biotin-dependent cell envelope remodelling is required for Mycobacterium abscessus survival in lung infection. Nat Microbiol 2023; 8:481-497. [PMID: 36658396 PMCID: PMC9992005 DOI: 10.1038/s41564-022-01307-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 12/14/2022] [Indexed: 01/21/2023]
Abstract
Mycobacterium abscessus is an emerging pathogen causing lung infection predominantly in patients with underlying structural abnormalities or lung disease and is resistant to most frontline antibiotics. As the pathogenic mechanisms of M. abscessus in the context of the lung are not well-understood, we developed an infection model using air-liquid interface culture and performed a transposon mutagenesis and sequencing screen to identify genes differentially required for bacterial survival in the lung. Biotin cofactor synthesis was required for M. abscessus growth due to increased intracellular biotin demand, while pharmacological inhibition of biotin synthesis prevented bacterial proliferation. Biotin was required for fatty acid remodelling, which increased cell envelope fluidity and promoted M. abscessus survival in the alkaline lung environment. Together, these results indicate that biotin-dependent fatty acid remodelling plays a critical role in pathogenic adaptation to the lung niche, suggesting that biotin synthesis and fatty acid metabolism might provide therapeutic targets for treatment of M. abscessus infection.
Collapse
Affiliation(s)
- Mark R Sullivan
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Kerry McGowen
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Qiang Liu
- Department of Medicinal Chemistry, University of Minnesota College of Pharmacy, Minneapolis, MN, USA
| | - Chidiebere Akusobi
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - David C Young
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jacob A Mayfield
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Sahadevan Raman
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ian D Wolf
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - D Branch Moody
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota College of Pharmacy, Minneapolis, MN, USA
| | - Alexander Muir
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL, USA
| | - Eric J Rubin
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
| |
Collapse
|
9
|
Abstract
The genus Mycobacterium contains several slow-growing human pathogens, including Mycobacterium tuberculosis, Mycobacterium leprae, and Mycobacterium avium. Mycobacterium smegmatis is a nonpathogenic and fast growing species within this genus. In 1990, a mutant of M. smegmatis, designated mc2155, that could be transformed with episomal plasmids was isolated, elevating M. smegmatis to model status as the ideal surrogate for mycobacterial research. Classical bacterial models, such as Escherichia coli, were inadequate for mycobacteria research because they have low genetic conservation, different physiology, and lack the novel envelope structure that distinguishes the Mycobacterium genus. By contrast, M. smegmatis encodes thousands of conserved mycobacterial gene orthologs and has the same cell architecture and physiology. Dissection and characterization of conserved genes, structures, and processes in genetically tractable M. smegmatis mc2155 have since provided previously unattainable insights on these same features in its slow-growing relatives. Notably, tuberculosis (TB) drugs, including the first-line drugs isoniazid and ethambutol, are active against M. smegmatis, but not against E. coli, allowing the identification of their physiological targets. Furthermore, Bedaquiline, the first new TB drug in 40 years, was discovered through an M. smegmatis screen. M. smegmatis has become a model bacterium, not only for M. tuberculosis, but for all other Mycobacterium species and related genera. With a repertoire of bioinformatic and physical resources, including the recently established Mycobacterial Systems Resource, M. smegmatis will continue to accelerate mycobacterial research and advance the field of microbiology.
Collapse
|
10
|
Olivença F, Ferreira C, Nunes A, Silveiro C, Pimentel M, Gomes JP, Catalão MJ. Identification of drivers of mycobacterial resistance to peptidoglycan synthesis inhibitors. Front Microbiol 2022; 13:985871. [PMID: 36147841 PMCID: PMC9485614 DOI: 10.3389/fmicb.2022.985871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/02/2022] [Indexed: 11/13/2022] Open
Abstract
Beta-lactams have been excluded from tuberculosis therapy due to the intrinsic resistance of Mycobacterium tuberculosis (Mtb) to this antibiotic class, usually attributed to a potent beta-lactamase, BlaC, and to an unusually complex cell wall. In this pathogen, the peptidoglycan is cross-linked by penicillin-binding proteins (PBPs) and L,D-transpeptidases, the latter resistant to inhibition by most beta-lactams. However, recent studies have shown encouraging results of beta-lactam/beta-lactamase inhibitor combinations in clinical strains. Additional research on the mechanisms of action and resistance to these antibiotics and other inhibitors of peptidoglycan synthesis, such as the glycopeptides, is crucial to ascertain their place in alternative regimens against drug-resistant strains. Within this scope, we applied selective pressure to generate mutants resistant to amoxicillin, meropenem or vancomycin in Mtb H37Rv or Mycolicibacterium smegmatis (Msm) mc2-155. These were phenotypically characterized, and whole-genome sequencing was performed. Mutations in promising targets or orthologue genes were inspected in Mtb clinical strains to establish potential associations between altered susceptibility to beta-lactams and the presence of key genomic signatures. The obtained isolates had substantial increases in the minimum inhibitory concentration of the selection antibiotic, and beta-lactam cross-resistance was detected in Mtb. Mutations in L,D-transpeptidases and major PBPs, canonical targets, or BlaC were not found. The transcriptional regulator PhoP (Rv0757) emerged as a common denominator for Mtb resistance to both amoxicillin and meropenem, while Rv2864c, a lipoprotein with PBP activity, appears to be specifically involved in decreased susceptibility to the carbapenem. Nonetheless, the mutational pattern detected in meropenem-resistant mutants was different from the yielded by amoxicillin-or vancomycin-selected isolates, suggesting that distinct pathways may participate in increased resistance to peptidoglycan inhibitors, including at the level of beta-lactam subclasses. Cross-resistance between beta-lactams and antimycobacterials was mostly unnoticed, and Msm meropenem-resistant mutants from parental strains with previous resistance to isoniazid or ethambutol were isolated at a lower frequency. Although cell-associated nitrocefin hydrolysis was increased in some of the isolates, our findings suggest that traditional assumptions of Mtb resistance relying largely in beta-lactamase activity and impaired access of hydrophilic molecules through lipid-rich outer layers should be challenged. Moreover, the therapeutical potential of the identified Mtb targets should be explored.
Collapse
Affiliation(s)
- Francisco Olivença
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, Lisbon, Portugal
| | - Cláudia Ferreira
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, Lisbon, Portugal
| | - Alexandra Nunes
- Genomics and Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
- Faculty of Veterinary Medicine, Lusófona University, Lisbon, Portugal
| | - Cátia Silveiro
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, Lisbon, Portugal
| | - Madalena Pimentel
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, Lisbon, Portugal
| | - João Paulo Gomes
- Genomics and Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
- Faculty of Veterinary Medicine, Lusófona University, Lisbon, Portugal
| | - Maria João Catalão
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, Lisbon, Portugal
- *Correspondence: Maria João Catalão,
| |
Collapse
|