1
|
Nyblom M, Johnning A, Frykholm K, Wrande M, Müller V, Goyal G, Robertsson M, Dvirnas A, Sewunet T, KK S, Ambjörnsson T, Giske CG, Sandegren L, Kristiansson E, Westerlund F. Strain-level bacterial typing directly from patient samples using optical DNA mapping. Commun Med (Lond) 2023; 3:31. [PMID: 36823379 PMCID: PMC9950433 DOI: 10.1038/s43856-023-00259-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 02/09/2023] [Indexed: 02/25/2023] Open
Abstract
BACKGROUND Identification of pathogens is crucial to efficiently treat and prevent bacterial infections. However, existing diagnostic techniques are slow or have a too low resolution for well-informed clinical decisions. METHODS In this study, we have developed an optical DNA mapping-based method for strain-level bacterial typing and simultaneous plasmid characterisation. For the typing, different taxonomical resolutions were examined and cultivated pure Escherichia coli and Klebsiella pneumoniae samples were used for parameter optimization. Finally, the method was applied to mixed bacterial samples and uncultured urine samples from patients with urinary tract infections. RESULTS We demonstrate that optical DNA mapping of single DNA molecules can identify Escherichia coli and Klebsiella pneumoniae at the strain level directly from patient samples. At a taxonomic resolution corresponding to E. coli sequence type 131 and K. pneumoniae clonal complex 258 forming distinct groups, the average true positive prediction rates are 94% and 89%, respectively. The single-molecule aspect of the method enables us to identify multiple E. coli strains in polymicrobial samples. Furthermore, by targeting plasmid-borne antibiotic resistance genes with Cas9 restriction, we simultaneously identify the strain or subtype and characterize the corresponding plasmids. CONCLUSION The optical DNA mapping method is accurate and directly applicable to polymicrobial and clinical samples without cultivation. Hence, it has the potential to rapidly provide comprehensive diagnostics information, thereby optimizing early antibiotic treatment and opening up for future precision medicine management.
Collapse
Affiliation(s)
- My Nyblom
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Anna Johnning
- grid.5371.00000 0001 0775 6028Department of Mathematical Sciences, Chalmers University of Technology & University of Gothenburg, Gothenburg, 412 96 Sweden ,grid.452079.dDepartment of Systems and Data Analysis, Fraunhofer-Chalmers Centre, Gothenburg, 412 88 Sweden ,Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, 405 30 Sweden
| | - Karolin Frykholm
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Marie Wrande
- grid.8993.b0000 0004 1936 9457Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, 751 23 Sweden
| | - Vilhelm Müller
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Gaurav Goyal
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Miriam Robertsson
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Albertas Dvirnas
- grid.4514.40000 0001 0930 2361Department of Astronomy and Theoretical Physics, Lund University, Lund, 223 62 Sweden
| | - Tsegaye Sewunet
- grid.4714.60000 0004 1937 0626Department of Laboratory Medicine, Karolinska Institutet, Stockholm, 141 86 Sweden
| | - Sriram KK
- grid.5371.00000 0001 0775 6028Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96 Sweden
| | - Tobias Ambjörnsson
- grid.4514.40000 0001 0930 2361Department of Astronomy and Theoretical Physics, Lund University, Lund, 223 62 Sweden
| | - Christian G. Giske
- grid.4714.60000 0004 1937 0626Department of Laboratory Medicine, Karolinska Institutet, Stockholm, 141 86 Sweden ,grid.24381.3c0000 0000 9241 5705Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, 171 76 Sweden
| | - Linus Sandegren
- grid.8993.b0000 0004 1936 9457Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, 751 23 Sweden
| | - Erik Kristiansson
- Department of Mathematical Sciences, Chalmers University of Technology & University of Gothenburg, Gothenburg, 412 96, Sweden. .,Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, 405 30, Sweden.
| | - Fredrik Westerlund
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, 412 96, Sweden. .,Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, 405 30, Sweden.
| |
Collapse
|
2
|
KK S, Lin YL, Sewunet T, Wrande M, Sandegren L, Giske CG, Westerlund F. A Parallelized Nanofluidic Device for High-Throughput Optical DNA Mapping of Bacterial Plasmids. Micromachines (Basel) 2021; 12:1234. [PMID: 34683285 PMCID: PMC8538381 DOI: 10.3390/mi12101234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/05/2021] [Accepted: 10/08/2021] [Indexed: 12/03/2022]
Abstract
Optical DNA mapping (ODM) has developed into an important technique for DNA analysis, where single DNA molecules are sequence-specifically labeled and stretched, for example, in nanofluidic channels. We have developed an ODM assay to analyze bacterial plasmids-circular extrachromosomal DNA that often carry genes that make bacteria resistant to antibiotics. As for most techniques, the next important step is to increase throughput and automation. In this work, we designed and fabricated a nanofluidic device that, together with a simple automation routine, allows parallel analysis of up to 10 samples at the same time. Using plasmids encoding extended-spectrum beta-lactamases (ESBL), isolated from Escherichiacoli and Klebsiellapneumoniae, we demonstrate the multiplexing capabilities of the device when it comes to both many samples in parallel and different resistance genes. As a final example, we combined the device with a novel protocol for rapid cultivation and extraction of plasmids from fecal samples collected from patients. This combined protocol will make it possible to analyze many patient samples in one device already on the day the sample is collected, which is an important step forward for the ODM analysis of plasmids in clinical diagnostics.
Collapse
Affiliation(s)
- Sriram KK
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden; (S.K.); (Y.-L.L.)
| | - Yii-Lih Lin
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden; (S.K.); (Y.-L.L.)
| | - Tsegaye Sewunet
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, 141 52 Stockholm, Sweden; (T.S.); (C.G.G.)
| | - Marie Wrande
- Department of Medical Biochemistry and Microbiology, Uppsala University, 752 37 Uppsala, Sweden; (M.W.); (L.S.)
| | - Linus Sandegren
- Department of Medical Biochemistry and Microbiology, Uppsala University, 752 37 Uppsala, Sweden; (M.W.); (L.S.)
| | - Christian G. Giske
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, 141 52 Stockholm, Sweden; (T.S.); (C.G.G.)
- Clinical Microbiology, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Fredrik Westerlund
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden; (S.K.); (Y.-L.L.)
| |
Collapse
|
3
|
Wrande M, Vestö K, Puiac Banesaru S, Anwar N, Nordfjell J, Liu L, McInerney GM, Rhen M. Replication of Salmonella enterica serovar Typhimurium in RAW264.7 Phagocytes Correlates With Hypoxia and Lack of iNOS Expression. Front Cell Infect Microbiol 2020; 10:537782. [PMID: 33330118 PMCID: PMC7734562 DOI: 10.3389/fcimb.2020.537782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 11/02/2020] [Indexed: 11/13/2022] Open
Abstract
Salmonella infection associates with tissue hypoxia, while inducible nitric oxide synthase (iNOS), relying for its activity on molecular oxygen, stands as a central host defence measure in murine salmonellosis. Here, we have detailed hypoxia and iNOS responses of murine macrophage-like RAW264.7 cells upon infection with Salmonella enterica serovar Typhimurium. We noted that only a proportion of the infected RAW264.7 cells became hypoxic or expressed iNOS. Heavily infected cells became hypoxic, while in parallel such cells tended not to express iNOS. While a proportion of the infected RAW264.7 cells revealed shutdown of protein synthesis, this was only detectable after 12 h post infection and after iNOS expression was induced in the cell culture. Our data implicate an intrinsic heterogeneity with regard to hypoxia and iNOS expression in a cell culture-based infection setting.
Collapse
Affiliation(s)
- Marie Wrande
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Kim Vestö
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Speranta Puiac Banesaru
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Naeem Anwar
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Johan Nordfjell
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Lifeng Liu
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Gerald M McInerney
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Rhen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Biology, Umeå University, Umeå, Sweden
| |
Collapse
|
4
|
Müller V, Nyblom M, Johnning A, Wrande M, Dvirnas A, KK S, Giske CG, Ambjörnsson T, Sandegren L, Kristiansson E, Westerlund F. Cultivation-Free Typing of Bacteria Using Optical DNA Mapping. ACS Infect Dis 2020; 6:1076-1084. [PMID: 32294378 PMCID: PMC7304876 DOI: 10.1021/acsinfecdis.9b00464] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Indexed: 01/06/2023]
Abstract
A variety of pathogenic bacteria can infect humans, and rapid species identification is crucial for the correct treatment. However, the identification process can often be time-consuming and depend on the cultivation of the bacterial pathogen(s). Here, we present a stand-alone, enzyme-free, optical DNA mapping assay capable of species identification by matching the intensity profiles of large DNA molecules to a database of fully assembled bacterial genomes (>10 000). The assay includes a new data analysis strategy as well as a general DNA extraction protocol for both Gram-negative and Gram-positive bacteria. We demonstrate that the assay is capable of identifying bacteria directly from uncultured clinical urine samples, as well as in mixtures, with the potential to be discriminative even at the subspecies level. We foresee that the assay has applications both within research laboratories and in clinical settings, where the time-consuming step of cultivation can be minimized or even completely avoided.
Collapse
Affiliation(s)
- Vilhelm Müller
- Department of Biology
and Biological Engineering, Chalmers University
of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - My Nyblom
- Department of Biology
and Biological Engineering, Chalmers University
of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Anna Johnning
- Department of Mathematical
Sciences, Chalmers University of Technology
and the University of Gothenburg, 412 96 Gothenburg, Sweden
- Systems and Data Analysis, Fraunhofer-Chalmers
Centre, Chalmers Science
Park, 412 88 Gothenburg, Sweden
- Centre for Antibiotic Resistance Research,
CARe, University of Gothenburg, Box 440, 405 30 Gothenburg, Sweden
| | - Marie Wrande
- Department of Medical
Biochemistry and Microbiology, Uppsala University, Husargatan 3, Box
582, 751 23 Uppsala, Sweden
| | - Albertas Dvirnas
- Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, 223 62 Lund, Sweden
| | - Sriram KK
- Department of Biology
and Biological Engineering, Chalmers University
of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Christian G. Giske
- Department of Laboratory Medicine, Karolinska
Institutet, Alfred Nobels
Allé 8, 141 86 Stockholm, Sweden
- Department of Clinical
Microbiology, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Tobias Ambjörnsson
- Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, 223 62 Lund, Sweden
| | - Linus Sandegren
- Department of Medical
Biochemistry and Microbiology, Uppsala University, Husargatan 3, Box
582, 751 23 Uppsala, Sweden
| | - Erik Kristiansson
- Department of Mathematical
Sciences, Chalmers University of Technology
and the University of Gothenburg, 412 96 Gothenburg, Sweden
- Centre for Antibiotic Resistance Research,
CARe, University of Gothenburg, Box 440, 405 30 Gothenburg, Sweden
| | - Fredrik Westerlund
- Department of Biology
and Biological Engineering, Chalmers University
of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| |
Collapse
|
5
|
Del Bel Belluz L, Guidi R, Pateras IS, Levi L, Mihaljevic B, Rouf SF, Wrande M, Candela M, Turroni S, Nastasi C, Consolandi C, Peano C, Tebaldi T, Viero G, Gorgoulis VG, Krejsgaard T, Rhen M, Frisan T. The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection. PLoS Pathog 2016; 12:e1005528. [PMID: 27055274 PMCID: PMC4824513 DOI: 10.1371/journal.ppat.1005528] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 03/04/2016] [Indexed: 02/06/2023] Open
Abstract
Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this issue, we assessed the effects of the Salmonella enterica genotoxin, known as typhoid toxin, in in vivo models of murine infection. Immunocompetent mice were infected with isogenic S. enterica, serovar Typhimurium (S. Typhimurium) strains, encoding either a functional or an inactive typhoid toxin. The presence of the genotoxic subunit was detected 10 days post-infection in the liver of infected mice. Unexpectedly, its expression promoted the survival of the host, and was associated with a significant reduction of severe enteritis in the early phases of infection. Immunohistochemical and transcriptomic analysis confirmed the toxin-mediated suppression of the intestinal inflammatory response. The presence of a functional typhoid toxin further induced an increased frequency of asymptomatic carriers. Our data indicate that the typhoid toxin DNA damaging activity increases host survival and favours long-term colonization, highlighting a complex cross-talk between infection, DNA damage response and host immune response. These findings may contribute to understand why such effectors have been evolutionary conserved and horizontally transferred among Gram-negative bacteria.
Collapse
Affiliation(s)
- Lisa Del Bel Belluz
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Riccardo Guidi
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Ioannis S. Pateras
- Department of Histology and Embryology, School of Medicine, University of Athens, Athens, Greece
| | - Laura Levi
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Boris Mihaljevic
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Syed Fazle Rouf
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Marie Wrande
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Marco Candela
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Silvia Turroni
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Claudia Nastasi
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Clarissa Consolandi
- Institute of Biomedical Technologies, Italian National Research Council, Segrate, Milan, Italy
| | - Clelia Peano
- Institute of Biomedical Technologies, Italian National Research Council, Segrate, Milan, Italy
| | - Toma Tebaldi
- Centre for Integrative Biology University of Trento, Trento, Italy
| | | | - Vassilis G. Gorgoulis
- Department of Histology and Embryology, School of Medicine, University of Athens, Athens, Greece
- Biomedical Research Foundation, Academy of Athens, Athens, Greece
- Institute for Cancer Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
- Manchester Centre for Cellular Metabolism, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Thorbjørn Krejsgaard
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Mikael Rhen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Teresa Frisan
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
| |
Collapse
|
6
|
Knodler LA, Crowley SM, Sham HP, Yang H, Wrande M, Ma C, Ernst RK, Steele-Mortimer O, Celli J, Vallance BA. Noncanonical inflammasome activation of caspase-4/caspase-11 mediates epithelial defenses against enteric bacterial pathogens. Cell Host Microbe 2015; 16:249-256. [PMID: 25121752 DOI: 10.1016/j.chom.2014.07.002] [Citation(s) in RCA: 328] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/04/2014] [Accepted: 07/01/2014] [Indexed: 12/20/2022]
Abstract
Inflammasome-mediated host defenses have been extensively studied in innate immune cells. Whether inflammasomes function for innate defense in intestinal epithelial cells, which represent the first line of defense against enteric pathogens, remains unknown. We observed enhanced Salmonella enterica serovar Typhimurium colonization in the intestinal epithelium of caspase-11-deficient mice, but not at systemic sites. In polarized epithelial monolayers, siRNA-mediated depletion of caspase-4, a human ortholog of caspase-11, also led to increased bacterial colonization. Decreased rates of pyroptotic cell death, a host defense mechanism that extrudes S. Typhimurium-infected cells from the polarized epithelium, accounted for increased pathogen burdens. The caspase-4 inflammasome also governs activation of the proinflammatory cytokine, interleukin (IL)-18, in response to intracellular (S. Typhimurium) and extracellular (enteropathogenic Escherichia coli) enteric pathogens, via intracellular LPS sensing. Therefore, an epithelial cell-intrinsic noncanonical inflammasome plays a critical role in antimicrobial defense at the intestinal mucosal surface.
Collapse
Affiliation(s)
- Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA; Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA.
| | - Shauna M Crowley
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Ho Pan Sham
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Hyungjun Yang
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Marie Wrande
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA
| | - Caixia Ma
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA
| | - Olivia Steele-Mortimer
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA
| | - Jean Celli
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7090, USA; Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA
| | - Bruce A Vallance
- Division of Gastroenterology, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver BC V6H 3V4, Canada.
| |
Collapse
|
7
|
Abstract
Mutations in rpoB (RNA polymerase β-subunit) can cause high-level resistance to rifampicin, an important first-line drug against tuberculosis. Most rifampicin-resistant (Rif(R)) mutants selected in vitro have reduced fitness, and resistant clinical isolates of M. tuberculosis frequently carry multiple mutations in RNA polymerase genes. This supports a role for compensatory evolution in global epidemics of drug-resistant tuberculosis but the significance of secondary mutations outside rpoB has not been demonstrated or quantified. Using Salmonella as a model organism, and a previously characterized Rif(R) mutation (rpoB R529C) as a starting point, independent lineages were evolved with selection for improved growth in the presence and absence of rifampicin. Compensatory mutations were identified in every lineage and were distributed between rpoA, rpoB and rpoC. Resistance was maintained in all strains showing that increased fitness by compensatory mutation was more likely than reversion. Genetic reconstructions demonstrated that the secondary mutations were responsible for increasing growth rate. Many of the compensatory mutations in rpoA and rpoC individually caused small but significant reductions in susceptibility to rifampicin, and some compensatory mutations in rpoB individually caused high-level resistance. These findings show that mutations in different components of RNA polymerase are responsible for fitness compensation of a Rif(R) mutant.
Collapse
Affiliation(s)
- Gerrit Brandis
- Department of Medical Biochemistry and Microbiology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | | | | | | |
Collapse
|