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Abstract
Tuberculosis (TB) is one of the oldest health problems in the world and it remains unresolved. Multidrug-resistant-TB and extensively resistant-TB are a serious problem for control programs. The evaluation of available antibiotics has gained importance in recent years for the treatment of resistant TB. Beta-lactam antibiotics inhibit cell wall biosynthesis in the bacteria; the presence of beta-lactamase enzyme in TB bacilli raises the question of whether this group of antibiotics can be used in treatment. As a result, it has been reported that the combination of beta-lactam antibiotics with beta-lactamase is effective against Mycobacterium tuberculosis both in vitro and in vivo. The aim of this article is to review and discuss up-to-date knowledge and future perspective on beta-lactam antibiotics and TB.
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Affiliation(s)
- Mehmet Akif Gun
- Department of Medical Microbiology, Medical School, Ondokuz Mayis University, Samsun 55139, Turkey
| | - Bulent Bozdogan
- Recombinant DNA and Recombinant Protein Research Center (REDPROM), Aydin Adnan Menderes University, Aydin 09010, Turkey
| | - Ahmet Yilmaz Coban
- Tuberculosis Research Center, Akdeniz University, Antalya 07070, Turkey.,Department of Nutrition & Dietetics, Faculty of Health Sciences, Akdeniz University, Antalya 07070, Turkey
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2
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Lu Z, Wang H, Zhang A, Liu X, Zhou W, Yang C, Guddat L, Yang H, Schofield CJ, Rao Z. Structures of Mycobacterium tuberculosis Penicillin-Binding Protein 3 in Complex with Five β-Lactam Antibiotics Reveal Mechanism of Inactivation. Mol Pharmacol 2020; 97:287-294. [DOI: 10.1124/mol.119.118042] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 01/14/2020] [Indexed: 11/22/2022] Open
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3
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Amoxicillin-Clavulanate in Tuberculosis Disease. INFECTIOUS DISEASES IN CLINICAL PRACTICE 2019. [DOI: 10.1097/ipc.0000000000000715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4
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Ealand CS, Machowski EE, Kana BD. β-lactam resistance: The role of low molecular weight penicillin binding proteins, β-lactamases and ld-transpeptidases in bacteria associated with respiratory tract infections. IUBMB Life 2018; 70:855-868. [PMID: 29717815 DOI: 10.1002/iub.1761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/04/2018] [Indexed: 02/02/2023]
Abstract
Disruption of peptidoglycan (PG) biosynthesis in the bacterial cell wall by β-lactam antibiotics has transformed therapeutic options for bacterial infections. These antibiotics target the transpeptidase domains in penicillin binding proteins (PBPs), which can be classified into high and low molecular weight (LMW) counterparts. While the essentiality of the former has been extensively demonstrated, the physiological roles of LMW PBPs remain poorly understood. Herein, we review the function of LMW PBPs, β-lactamases and ld-transpeptidases (Ldts) in pathogens associated with respiratory tract infections. More specifically, we explore their roles in mediating β-lactam resistance. Using a comparative genomics approach, we identified a high degree of genetic redundancy for LMW PBPs which retain the motifs, SxxN, SxN and KTG required for catalytic activity. Differences in domain architecture suggest distinct physiological roles, possibly related to bacterial cell cycle and/or adaptation to various environmental conditions. Many of the LMW PBPs play an important role in β-lactam resistance either through mutation or variation in abundance. In all of the bacterial genomes assessed, at least one β-lactamase homologue is present, suggesting that enzymatic degradation of β-lactams is a highly conserved resistance mechanism. Furthermore, the presence of Ldt homologues in the majority of species surveyed suggests that alternative PG crosslinking may further mediate β-lactam drug resistance. A deeper understanding of the interplay between these different mechanisms of β-lactam resistance will provide a framework for new therapeutics, which are urgently required given the rapid emergence of antimicrobial resistance. © 2018 IUBMB Life, 70(9):855-868, 2018.
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Affiliation(s)
- Christopher S Ealand
- 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, Johannesburg, South Africa
| | - Edith E Machowski
- 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, Johannesburg, South Africa
| | - 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, Johannesburg, South Africa.,MRC-CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Centre for the AIDS Programme of Research in South Africa, CAPRISA, Durban, South Africa
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5
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2-aminoimidazoles potentiate ß-lactam antimicrobial activity against Mycobacterium tuberculosis by reducing ß-lactamase secretion and increasing cell envelope permeability. PLoS One 2017; 12:e0180925. [PMID: 28749949 PMCID: PMC5547695 DOI: 10.1371/journal.pone.0180925] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 06/23/2017] [Indexed: 11/21/2022] Open
Abstract
There is an urgent need to develop new drug treatment strategies to control the global spread of drug-sensitive and multidrug-resistant Mycobacterium tuberculosis (M. tuberculosis). The ß-lactam class of antibiotics is among the safest and most widely prescribed antibiotics, but they are not effective against M. tuberculosis due to intrinsic resistance. This study shows that 2-aminoimidazole (2-AI)-based small molecules potentiate ß-lactam antibiotics against M. tuberculosis. Active 2-AI compounds significantly reduced the minimal inhibitory and bactericidal concentrations of ß-lactams by increasing M. tuberculosis cell envelope permeability and decreasing protein secretion including ß-lactamase. Metabolic labeling and transcriptional profiling experiments revealed that 2-AI compounds impair mycolic acid biosynthesis, export and linkage to the mycobacterial envelope, counteracting an important defense mechanism reducing permeability to external agents. Additionally, other important constituents of the M. tuberculosis outer membrane including sulfolipid-1 and polyacyltrehalose were also less abundant in 2-AI treated bacilli. As a consequence of 2-AI treatment, M. tuberculosis displayed increased sensitivity to SDS, increased permeability to nucleic acid staining dyes, and rapid binding of cell wall targeting antibiotics. Transcriptional profiling analysis further confirmed that 2-AI induces transcriptional regulators associated with cell envelope stress. 2-AI based small molecules potentiate the antimicrobial activity of ß-lactams by a mechanism that is distinct from specific inhibitors of ß-lactamase activity and therefore may have value as an adjunctive anti-TB treatment.
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6
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Abstract
The complex cell envelope is a hallmark of mycobacteria and is anchored by the peptidoglycan layer, which is similar to that of Escherichia coli and a number of other bacteria but with modifications to the monomeric units and other structural complexities that are likely related to a role for the peptidoglycan in stabilizing the mycolyl-arabinogalactan-peptidoglycan complex (MAPc). In this article, we will review the genetics of several aspects of peptidoglycan biosynthesis in mycobacteria, including the production of monomeric precursors in the cytoplasm, assembly of the monomers into the mature wall, cell wall turnover, and cell division. Finally, we will touch upon the resistance of mycobacteria to β-lactam antibiotics, an important class of drugs that, until recently, have not been extensively exploited as potential antimycobacterial agents. We will also note areas of research where there are still unanswered questions.
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Goldani LZ, Spessatto CO, Nunes DL, Oliveira JG, Takamatu E, Cerski CT, Goldani HAS. Management of Severe Gastrointestinal Tuberculosis with Injectable Antituberculous Drugs. Trop Med Health 2015; 43:191-4. [PMID: 26543395 PMCID: PMC4593777 DOI: 10.2149/tmh.2015-09] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/03/2015] [Indexed: 12/29/2022] Open
Abstract
Abdominal tuberculosis (TB) is generally responsive to medical treatment, and early diagnosis and management can prevent unnecessary surgical intervention. However, intravenous therapy is needed for severe forms of tuberculosis with extensive gastrointestinal involvement. The authors report an immunocompetent patient with gastrointestinal TB who was successfully managed with a combination of surgical intervention and anti-TB medications, and discuss the importance of injectable anti-TB medications in the management of severe gastrointestinal TB. The present case report provides a model for assessment and intervention in severe forms of gastrointestinal TB.
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Affiliation(s)
- Luciano Z Goldani
- Infectious Diseases Section, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Camila O Spessatto
- Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Daltro L Nunes
- Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Juliana G Oliveira
- Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Eliziane Takamatu
- Pediatric Surgery Section, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Carlos T Cerski
- Pathology Section, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
| | - Helena A S Goldani
- Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul , Brazil
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8
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Meropenem-clavulanic acid has high in vitro activity against multidrug-resistant Mycobacterium tuberculosis. Antimicrob Agents Chemother 2015; 59:3630-2. [PMID: 25824227 DOI: 10.1128/aac.00171-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/23/2015] [Indexed: 11/20/2022] Open
Abstract
We investigated the activity of meropenem-clavulanic acid (MEM-CLA) against 68 Mycobacterium tuberculosis isolates. We included predominantly multi- and extensively drug-resistant tuberculosis (MDR/XDR-TB) isolates, since the activity of MEM-CLA for resistant isolates has previously not been studied extensively. Using Middlebrook 7H10 medium, all but four isolates showed an MIC distribution of 0.125 to 2 mg/liter for MEM-CLA, below the non-species-related breakpoint for MEM of 2 mg/liter defined by EUCAST. MEM-CLA is a potential treatment option for MDR/XDR-TB.
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9
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Mechanisms of β-lactam killing and resistance in the context of Mycobacterium tuberculosis. J Antibiot (Tokyo) 2014; 67:645-54. [PMID: 25052484 DOI: 10.1038/ja.2014.94] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 04/21/2014] [Accepted: 05/16/2014] [Indexed: 02/07/2023]
Abstract
β-Lactams are one of the most useful classes of antibiotics against many common bacterial pathogens. One exception is Mycobacterium tuberculosis. However, with increasing incidence of multidrug-resistant tuberculosis and a need for new agents to treat it, the use of β-lactams, specifically the combination of carbapenem and clavulanate, is now being revisited. With this attention, comes the need to better understand both the mechanisms of action of β-lactams against M. tuberculosis as well as possible mechanisms of resistance, within the context of what is known about the β-lactam action in other bacteria. M. tuberculosis has two major mechanisms of intrinsic resistance: a highly active β-lactamase and a poorly permeable outer membrane. Within the cell wall, β-lactams bind several enzymes with differing peptidoglycan-synthetic and -lytic functions. The inhibition of these enzymes may lead to cell death through several mechanisms, involving disruption of the balance of synthetic and lethal activities. Currently, all known means of resistance to the β-lactams rely on diminishing the proportion of peptidoglycan-synthetic proteins bound and inhibited by β-lactams, through either exclusion or destruction of the antibiotic, or through replacement or supplementation of target enzymes. In this review, we discuss possible mechanisms for β-lactam activity in M. tuberculosis and the means by which it may acquire resistance, within the context of what is known in other bacterial species.
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10
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Boff DF, Goldani LZ. Initial combination of injectable and oral anti-tuberculosis agents for the treatment of severe disseminated tuberculosis. Trop Doct 2013; 43:148-50. [PMID: 24096909 DOI: 10.1177/0049475513502961] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is a need for intravenous therapy for severe forms of tuberculosis in those who are HIV-positive, diabetic, have cystic fibrosis, extensive gastrointestinal involvement, haemodynamic instability with difficulty to take and absorb oral medications, which results in a lack of appropriate therapeutic effect during treatment, such as not creating the optimal blood concentration of the substance. We report an HIV-infected patient presenting with severe disseminated tuberculosis with extensive intestinal involvement which was successfully treated with an initial combination regimen of injectable and oral anti-tuberculosis agents. We discuss and emphasize the importance of an initial regimen with injectable and oral agents for treating severe forms of tuberculosis.
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Affiliation(s)
- Diego F Boff
- MD, Infectious Disease Section, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90640-000, Brazil.
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11
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Kurz SG, Bonomo RA. Reappraising the use of β-lactams to treat tuberculosis. Expert Rev Anti Infect Ther 2013; 10:999-1006. [PMID: 23106275 DOI: 10.1586/eri.12.96] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The emergence of multidrug-resistant and extensively drug-resistant tuberculosis calls for novel approaches to treatment. Recent studies have shown that BlaC, the β-lactamase of Mycobacterium tuberculosis, is the major determinant of β-lactam resistance. This review invites the reader to explore evidence in order to answer the questions: can β-lactam and β-lactamase inhibitors adequately treat M. tuberculosis infection and are they a viable option in the management of resistant tuberculosis today?
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Affiliation(s)
- Sebastian G Kurz
- Division of Pulmonary, Critical Care and Sleep Medicine, University Hospitals Case Medical Center and Louis Stokes Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA
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12
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Seddon JA, Hesseling AC, Marais BJ, McIlleron H, Peloquin CA, Donald PR, Schaaf HS. Paediatric use of second-line anti-tuberculosis agents: a review. Tuberculosis (Edinb) 2011; 92:9-17. [PMID: 22118883 DOI: 10.1016/j.tube.2011.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 09/25/2011] [Accepted: 11/01/2011] [Indexed: 11/18/2022]
Abstract
Childhood multidrug-resistant tuberculosis (MDR-TB) is an emerging global epidemic. With the imminent roll-out of rapid molecular diagnostic tests, more children are likely to be identified and require treatment. As MDR-TB is resistant to the most effective first-line drugs, clinicians will have to rely on second-line medications which are less effective and often associated with more pronounced adverse effects than first-line therapy. Despite the fact that most of these agents were discovered many years ago, robust information is lacking regarding their pharmacokinetic and pharmacodynamic properties, adverse effects and drug interactions, especially in children. Children differ from adults in the way that drugs are administered, the manner in which they are metabolised and in the adverse effects experienced. The interaction of these drugs with human immunodeficiency virus infection and antiretroviral therapy is also poorly documented. This article reviews the available second-line drugs currently used in the treatment of MDR-TB in children and discusses medication properties and adverse effects while potential interactions with antiretroviral therapy are explored.
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Affiliation(s)
- James A Seddon
- Desmond Tutu TB Centre, Faculty of Health Sciences, Stellenbosch University, South Africa.
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13
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Marriner GA, Nayyar A, Uh E, Wong SY, Mukherjee T, Via LE, Carroll M, Edwards RL, Gruber TD, Choi I, Lee J, Arora K, England KD, Boshoff HIM, Barry CE. The Medicinal Chemistry of Tuberculosis Chemotherapy. TOPICS IN MEDICINAL CHEMISTRY 2011. [DOI: 10.1007/7355_2011_13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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14
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Fedarovich A, Nicholas RA, Davies C. Unusual conformation of the SxN motif in the crystal structure of penicillin-binding protein A from Mycobacterium tuberculosis. J Mol Biol 2010; 398:54-65. [PMID: 20206184 DOI: 10.1016/j.jmb.2010.02.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 02/23/2010] [Accepted: 02/24/2010] [Indexed: 11/17/2022]
Abstract
PBPA from Mycobacterium tuberculosis is a class B-like penicillin-binding protein (PBP) that is not essential for cell growth in M. tuberculosis, but is important for proper cell division in Mycobacterium smegmatis. We have determined the crystal structure of PBPA at 2.05 A resolution, the first published structure of a PBP from this important pathogen. Compared to other PBPs, PBPA has a relatively small N-terminal domain, and conservation of a cluster of charged residues within this domain suggests that PBPA is more related to class B PBPs than previously inferred from sequence analysis. The C-terminal domain is a typical transpeptidase fold and contains the three conserved active-site motifs characteristic of penicillin-interacting enzymes. Whilst the arrangement of the SxxK and KTG motifs is similar to that observed in other PBPs, the SxN motif is markedly displaced away from the active site, such that its serine (Ser281) is not involved in hydrogen bonding with residues of the other two motifs. A disulfide bridge between Cys282 (the "x" of the SxN motif) and Cys266, which resides on an adjacent loop, may be responsible for this unusual conformation. Another interesting feature of the structure is a relatively long connection between beta 5 and alpha 11, which restricts the space available in the active site of PBPA and suggests that conformational changes would be required to accommodate peptide substrate or beta-lactam antibiotics during acylation. Finally, the structure shows that one of the two threonines postulated to be targets for phosphorylation is inaccessible (Thr362), whereas the other (Thr437) is well placed on a surface loop near the active site.
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Affiliation(s)
- Alena Fedarovich
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA
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Hugonnet JE, Tremblay LW, Boshoff HI, Barry CE, Blanchard JS. Meropenem-clavulanate is effective against extensively drug-resistant Mycobacterium tuberculosis. Science 2009; 323:1215-8. [PMID: 19251630 PMCID: PMC2679150 DOI: 10.1126/science.1167498] [Citation(s) in RCA: 372] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
beta-lactam antibiotics are ineffective against Mycobacterium tuberculosis, being rapidly hydrolyzed by the chromosomally encoded blaC gene product. The carbapenem class of beta-lactams are very poor substrates for BlaC, allowing us to determine the three-dimensional structure of the covalent BlaC-meropenem covalent complex at 1.8 angstrom resolution. When meropenem was combined with the beta-lactamase inhibitor clavulanate, potent activity against laboratory strains of M. tuberculosis was observed [minimum inhibitory concentration (MIC(meropenem)) less than 1 microgram per milliliter], and sterilization of aerobically grown cultures was observed within 14 days. In addition, this combination exhibited inhibitory activity against anaerobically grown cultures that mimic the "persistent" state and inhibited the growth of 13 extensively drug-resistant strains of M. tuberculosis at the same levels seen for drug-susceptible strains. Meropenem and clavulanate are Food and Drug Administration-approved drugs and could potentially be used to treat patients with currently untreatable disease.
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Affiliation(s)
- Jean-Emmanuel Hugonnet
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Lee W. Tremblay
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Helena I. Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Clifton E. Barry
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - John S. Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Nampoothiri K, Rubex R, Patel A, Narayanan S, Krishna S, Das S, Pandey A. Molecular cloning, overexpression and biochemical characterization of hypothetical β-lactamases ofMycobacterium tuberculosisH37Rv. J Appl Microbiol 2008; 105:59-67. [DOI: 10.1111/j.1365-2672.2007.03721.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Akhter Y, Yellaboina S, Farhana A, Ranjan A, Ahmed N, Hasnain SE. Genome scale portrait of cAMP-receptor protein (CRP) regulons in mycobacteria points to their role in pathogenesis. Gene 2007; 407:148-58. [PMID: 18022770 DOI: 10.1016/j.gene.2007.10.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 10/02/2007] [Accepted: 10/05/2007] [Indexed: 10/22/2022]
Abstract
cAMP Receptor Protein (CRP)/Fumarate Nitrate Reductase Regulator (FNR) family proteins are ubiquitous regulators of cell stress in eubacteria. These proteins are commonly associated with maintenance of intracellular oxygen levels, redox-state, oxidative and nitrosative stresses, and extreme temperature conditions by regulating expression of target genes that contain regulatory cognate DNA elements. We describe the use of informatics enabled comparative genomics to identify novel genes under the control of CRP regulator in Mycobacterium tuberculosis (M.tb). An inventory of CRP regulated genes and their operon context in important mycobacterial species such as M. leprae, M. avium subsp. paratuberculosis and M. smegmatis and several common genes within this genus including the important cellular functions, mainly, cell-wall biogenesis, cAMP signaling and metabolism associated with such regulons were identified. Our results provide a possible theoretical framework for better understanding of the stress response in mycobacteria. The conservation of the CRP regulated genes in pathogenic mycobacteria, as opposed to non-pathogenic ones, highlights the importance of CRP-regulated genes in pathogenesis.
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Affiliation(s)
- Yusuf Akhter
- Laboratory of Molecular and Cellular Biology, CDFD, Hyderabad, India
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18
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Wang F, Cassidy C, Sacchettini JC. Crystal structure and activity studies of the Mycobacterium tuberculosis beta-lactamase reveal its critical role in resistance to beta-lactam antibiotics. Antimicrob Agents Chemother 2006; 50:2762-71. [PMID: 16870770 PMCID: PMC1538687 DOI: 10.1128/aac.00320-06] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
beta-Lactam antibiotics are extremely effective in disrupting the synthesis of the bacterial cell wall in both gram-positive and gram-negative bacteria. However, they are ineffective against Mycobacterium tuberculosis, due to the production of a beta-lactamase enzyme encoded on the chromosome of M. tuberculosis that degrades these antibiotics. Indeed, recent studies have demonstrated that deletion of the blaC gene, the only gene encoding a beta-lactamase in M. tuberculosis, or inhibition of the encoded enzyme resulted in significantly increased sensitivity to beta-lactam antibiotics. In this paper we present a biochemical and structural characterization of M. tuberculosis BlaC. Recombinant BlaC shows a broad range of specificity with almost equal penicillinase and cepholothinase activity. While clavulanate is a mechanism-based inhibitor to class A beta-lactamase with high potency (typically K(i) < 0.1 microM), it is a relatively poor inhibitor of the M. tuberculosis BlaC (K(i) = 2.4 microM). The crystal structure of the enzyme, determined at a resolution of 1.7 A, shows that the overall fold of the M. tuberculosis enzyme is similar to other class A beta-lactamases. There are, however, several distinct features of the active site, such as the amino acid substitutions N132G, R164A, R244A, and R276E, that explain the broad specificity of the enzyme, relatively low penicillinase activity, and resistance to clavulanate.
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Affiliation(s)
- Feng Wang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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19
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Flores AR, Parsons LM, Pavelka MS. Genetic analysis of the beta-lactamases of Mycobacterium tuberculosis and Mycobacterium smegmatis and susceptibility to beta-lactam antibiotics. MICROBIOLOGY-SGM 2005; 151:521-532. [PMID: 15699201 DOI: 10.1099/mic.0.27629-0] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mycobacteria produce beta-lactamases and are intrinsically resistant to beta-lactam antibiotics. In addition to the beta-lactamases, cell envelope permeability and variations in certain peptidoglycan biosynthetic enzymes are believed to contribute to beta-lactam resistance in these organisms. To allow the study of these additional mechanisms, mutants of the major beta-lactamases, BlaC and BlaS, were generated in the pathogenic Mycobacterium tuberculosis strain H37Rv and the model organism Mycobacterium smegmatis strain PM274. The mutants M. tuberculosis PM638 (DeltablaC1) and M. smegmatis PM759 (DeltablaS1) showed an increase in susceptibility to beta-lactam antibiotics, as determined by disc diffusion and minimal inhibitory concentration (MIC) assays. The susceptibility of the mutants, as assayed by disc diffusion tests, to penicillin-type beta-lactam antibiotics was affected most, compared to the cephalosporin-type beta-lactam antibiotics. The M. tuberculosis mutant had no detectable beta-lactamase activity, while the M. smegmatis mutant had a residual type 1 beta-lactamase activity. We identified a gene, blaE, encoding a putative cephalosporinase in M. smegmatis. A double beta-lactamase mutant of M. smegmatis, PM976 (DeltablaS1DeltablaE : : res), had no detectable beta-lactamase activity, but its susceptibility to beta-lactam antibiotics was not significantly different from that of the DeltablaS1 parental strain, PM759. The mutants generated in this study will help determine the contribution of other beta-lactam resistance mechanisms in addition to serving as tools to study the biology of peptidoglycan biosynthesis in these organisms.
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Affiliation(s)
- Anthony R Flores
- University of Rochester School of Medicine and Dentistry and Department of Microbiology and Immunology, Rochester, NY 14642, USA
| | - Linda M Parsons
- The Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Martin S Pavelka
- University of Rochester School of Medicine and Dentistry and Department of Microbiology and Immunology, Rochester, NY 14642, USA
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Philalay JS, Palermo CO, Hauge KA, Rustad TR, Cangelosi GA. Genes required for intrinsic multidrug resistance in Mycobacterium avium. Antimicrob Agents Chemother 2004; 48:3412-8. [PMID: 15328105 PMCID: PMC514743 DOI: 10.1128/aac.48.9.3412-3418.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genes required for intrinsic multidrug resistance by Mycobacterium avium were identified by screening a library of transposon insertion mutants for the inability to grow in the presence of ciprofloxacin, clarithromycin, and penicillin at subinhibitory concentrations. Two genes, pks12 and Maa2520, were disrupted in multiple drug-susceptible mutants. The pks12 gene (Maa1979), which may be cotranscribed with a downstream gene (Maa1980), is widely conserved in the actinomycetes. Its ortholog in Mycobacterium tuberculosis is a polyketide synthase required for the synthesis of dimycocerosyl phthiocerol, a major cell wall lipid. Mutants of M. avium with insertions into pks12 exhibited altered colony morphology and were drug susceptible, but they grew as well as the wild type did in vitro and intracellularly within THP-1 cells. A pks12 mutant of M. tuberculosis was moderately more susceptible to clarithromycin than was its parent strain; however, susceptibility to ciprofloxacin and penicillin was not altered. M. avium complex (MAC) and M. tuberculosis appear to have different genetic mechanisms for resisting the effects of these antibiotics, with pks12 playing a relatively more significant role in MAC. The second genetic locus identified in this study, Maa2520, is a conserved hypothetical gene with orthologs in M. tuberculosis and Mycobacterium leprae. It is immediately upstream of Maa2521, which may code for an exported protein. Mutants with insertions at this locus were susceptible to multiple antibiotics and slow growing in vitro and were unable to survive intracellularly within THP-1 cells. Like pks12 mutants, they exhibited increased Congo red binding, an indirect indication of cell wall modifications. Maa2520 and pks12 are the first genes to be linked by mutation to intrinsic drug resistance in MAC.
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Affiliation(s)
- Julie S Philalay
- Seattle Biomedical Research Institute, 4 Nickerson St., Seattle, WA 98109, USA
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Dinçer I, Ergin A, Kocagöz T. The vitro efficacy of beta-lactam and beta-lactamase inhibitors against multidrug resistant clinical strains of Mycobacterium tuberculosis. Int J Antimicrob Agents 2004; 23:408-11. [PMID: 15081094 DOI: 10.1016/j.ijantimicag.2003.09.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Accepted: 09/22/2003] [Indexed: 11/19/2022]
Abstract
In vitro activity of beta-lactam antibiotics and their beta-lactamase inhibitor combinations were evaluated for their activity against clinical isolates of Mycobacterium tuberculosis and M. tuberculosis H37Ra. Agar dilution, the BACTEC 460 system and beta-lactamase activity tests were used. Results using the BACTEC 460 and enzyme activity tests showed the best beta-lactamase inhibitor for M. tuberculosis H37Ra to be clavulanic acid. Cefazolin-clavulanic acid gave the lowest minimal inhibitory concentration (MIC) values using dilution tests and M. tuberculosis H37Ra. beta-Lactam antibiotics were combined with clavulanic acid and tested for in vitro activity against 50 selected multidrug-resistant (MDR) and 50 susceptible clinical isolates. Seventy-four percent of the isolates were inhibited by cefazolin-clavulanic acid combination. These results suggested that an appropriate combination of beta-lactam and beta-lactamase inhibitors might be useful in the treatment of tuberculosis due to multidrug-resistant strains.
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Affiliation(s)
- Irem Dinçer
- Department of Microbiology and Clinical Microbiology, School of Medicine, Hacettepe University, Ankara, Turkey
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Abstract
Drug-resistant tuberculosis (TB) represents a threat to TB control programmes. Erratic and inappropriate use of currently available medications, HIV-TB co-infection, and concern about transmission of drug-resistant strains in the general population all contribute to a worrying picture. What do we do now? In the last few years, there has been considerable progress in the understanding of mechanisms of action and resistance to antituberculosis agents, and in establishing the value of directly observed therapy in preventing treatment failure. However, a limited effort has been devoted to the development of new active compounds or of rapid diagnostic tests, and their relevance to global tuberculosis control has been questioned.
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Affiliation(s)
- A Telenti
- Division of Infectious Diseases and Institute of Microbiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
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