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Bagheri M, Pormohammad A, Fardsanei F, Yadegari A, Arshadi M, Deihim B, Hajikhani B, Turner RJ, Khalili F, Mousavi SMJ, Dadashi M, Goudarzi M, Dabiri H, Goudarzi H, Mirsaeidi M, Nasiri MJ. Diagnostic Accuracy of Pyrazinamide Susceptibility Testing in Mycobacterium tuberculosis: A Systematic Review with Meta-Analysis. Microb Drug Resist 2021; 28:87-98. [PMID: 34582723 DOI: 10.1089/mdr.2021.0048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: Pyrazinamide (PZA) susceptibility testing plays a critical role in determining the appropriate treatment regimens for multidrug-resistant tuberculosis. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of sequencing PZA susceptibility tests against culture-based susceptibility testing methods as the reference standard. Methods: We searched the MEDLINE/PubMed, Embase, and Web of Science databases for the relevant records. The QUADAS-2 tool was used to assess the quality of the studies. Diagnostic accuracy measures (i.e., sensitivity and specificity) were pooled with a random-effects model. All statistical analyses were performed with Meta-DiSc (version 1.4, Cochrane Colloquium, Barcelona, Spain), STATA (version 14, Stata Corporation, College Station, TX), and RevMan (version 5.3, The Nordic Cochrane Centre, the Cochrane Collaboration, Copenhagen, Denmark) software. Results: A total of 72 articles, published between 2000 and 2019, comprising data for 8,701 isolates of Mycobacterium tuberculosis were included in the final analysis. The pooled sensitivity and specificity of the PZA sequencing test against all reference tests (the combination of BACTEC mycobacteria growth indicator tube 960 (MGIT 960), BACTEC 460, and proportion method) were 87% (95% CI: 85-88) and 94.7% (95% CI: 94-95). The positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and the area under the curve estimates were found to be 12.0 (95% CI: 9.0-16.0), 0.17 (95% CI: 0.13-0.21), 106 (95% CI: 71-158), and 96%, respectively. Deek's test result indicated a low likelihood for publication bias (p = 0.01). Conclusions: Our analysis indicated that PZA sequencing may be used in combination with conventional tests due to the advantage of the time to result and in scenarios where culture tests are not feasible. Further work to improve molecular tests would benefit from the availability of standardized reference standards and improvements to the methodology.
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Affiliation(s)
- Mohammad Bagheri
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Pormohammad
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Fatemeh Fardsanei
- Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Ali Yadegari
- School of Medicine, Mazandaran University of Medical Sciences, Mazandaran, Iran
| | - Maniya Arshadi
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Behnaz Deihim
- Department of Bacteriology and Virology, School of Medicine, Dezful University of Medical Sciences, Dezful, Iran
| | - Bahareh Hajikhani
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ray J Turner
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Farima Khalili
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Masoud Dadashi
- Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Mehdi Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Dabiri
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Mirsaeidi
- Division of Pulmonary and Critical Care, College of Medicine-Jacksonville, University of Florida, Jacksonville, FL, USA
| | - Mohammad Javad Nasiri
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Nasiri MJ, Fardsanei F, Arshadi M, Deihim B, Khalili F, Dadashi M, Goudarzi M, Mirsaeidi M. Performance of Wayne assay for detection of pyrazinamide resistance in Mycobacterium tuberculosis: a meta-analysis study. New Microbes New Infect 2021; 42:100886. [PMID: 34141437 PMCID: PMC8184659 DOI: 10.1016/j.nmni.2021.100886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 11/30/2022] Open
Abstract
Conventional culture-based drug susceptibility testing (DST) of Mycobacterium tuberculosis to pyrazinamide (PZA) is time-consuming and difficult to perform. The current systematic review and meta-analysis was aimed to evaluate the diagnostic accuracy of Wayne assay against culture-based DSTs as the reference standard. We searched the MEDLINE/Pubmed, Embase, and Web of Science databases for the relevant records. The QUADAS-2 tool was used to assess the quality of the studies. Diagnostic accuracy measures (i.e., sensitivity and specificity) were pooled with a random-effects model. Statistical analyses were performed with STATA (version 14, Stata Corporation, College Station, TX, USA), RevMan (version 5.3; The Nordic Cochrane Centre, the Cochrane Collaboration, Copenhagen, Denmark), and Meta-DiSc (version 1.4, Cochrane Colloquium, Barcelona, Spain). A total of 31 articles comprising data for 2457 isolates of M. tuberculosis were included in the final analysis. The pooled sensitivity and specificity of the Wayne assay against all reference tests (the combination of BACTEC MGIT 960, BACTEC 460, and proportion method) were 86.6% (95% CI: 84.3-88.7) and 96.0% (95% CI: 94.8-97). The positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the area under the curve (AUC) estimates were found to be 17.6 (95% CI: 10.5-29.3), 0.11 (95% CI: 0.06-0.20), 164 (95% CI: 83-320) and 97%, respectively. Deek's test result indicated no evidence for publication bias (P > 0.05). Although the current study shows that the Wayne test is sensitive and specific for detecting PZA resistance, it may be used in combination with conventional DSTs to diagnose PZA resistance accurately.
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Affiliation(s)
- M J Nasiri
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - F Fardsanei
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - M Arshadi
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - B Deihim
- Department of Bacteriology and Virology, School of Medicine, Dezful University of Medical Sciences, Dezful, Iran
| | - Farima Khalili
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - M Dadashi
- Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - M Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - M Mirsaeidi
- Department of Pulmonary and Critical Care, University of Miami Miller School of Medicine, Miami, FL, USA
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Dookie N, Sturm AW, Moodley P. Mechanisms of first-line antimicrobial resistance in multi-drug and extensively drug resistant strains of Mycobacterium tuberculosis in KwaZulu-Natal, South Africa. BMC Infect Dis 2016; 16:609. [PMID: 27784282 PMCID: PMC5080726 DOI: 10.1186/s12879-016-1906-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 10/04/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND In South Africa, drug resistant tuberculosis is a major public health crisis in the face of the colossal HIV pandemic. METHODS In an attempt to understand the distribution of drug resistance in our setting, we analysed the rpoB, katG, inhA, pncA and embB genes associated with resistance to key drugs used in the treatment of tuberculosis in clinical isolates of Mycobacterium tuberculosis in the KwaZulu-Natal province. RESULTS Classical mutations were detected in the katG, inhA and embB genes associated with resistance to isoniazid and ethambutol. Diverse mutations were recorded in the multidrug resistant (MDR) and extensively drug resistant (XDR) isolates for the rpoB and pncA gene associated with resistance to rifampicin and pyrazinamide. CONCLUSIONS M.tuberculosis strains circulating in our setting display a combination of previously observed mutations, each mediating resistance to a different drug. The MDR and XDR TB isolates analysed in this study displayed classical mutations linked to INH and EMB resistance, whilst diverse mutations were linked to RIF and PZA resistance. The similarity of the XDR strains confirms reports of the clonality of the XDR epidemic. The successful dissemination of the drug resistant strains in the province underscores the need for rapid diagnostics to effectively diagnose drug resistance and guide treatment.
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Affiliation(s)
- Navisha Dookie
- Medical Microbiology and Infection Prevention and Control, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, Durban, South Africa
| | - A Willem Sturm
- Medical Microbiology and Infection Prevention and Control, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, Durban, South Africa
| | - Prashini Moodley
- Medical Microbiology and Infection Prevention and Control, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, Durban, South Africa.
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Whitfield MG, Soeters HM, Warren RM, York T, Sampson SL, Streicher EM, van Helden PD, van Rie A. A Global Perspective on Pyrazinamide Resistance: Systematic Review and Meta-Analysis. PLoS One 2015. [PMID: 26218737 PMCID: PMC4517823 DOI: 10.1371/journal.pone.0133869] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Background Pyrazinamide (PZA) is crucial for tuberculosis (TB) treatment, given its unique ability to eradicate persister bacilli. The worldwide burden of PZA resistance remains poorly described. Methods Systematic PubMed, Science Direct and Scopus searches for articles reporting phenotypic (liquid culture drug susceptibility testing or pyrazinamidase activity assays) and/or genotypic (polymerase chain reaction or DNA sequencing) PZA resistance. Global and regional summary estimates were obtained from random-effects meta-analysis, stratified by presence or risk of multidrug resistant TB (MDR-TB). Regional summary estimates were combined with regional WHO TB incidence estimates to determine the annual burden of PZA resistance. Information on single nucleotide polymorphisms (SNPs) in the pncA gene was aggregated to obtain a global summary. Results Pooled PZA resistance prevalence estimate was 16.2% (95% CI 11.2-21.2) among all TB cases, 41.3% (29.0-53.7) among patients at high MDR-TB risk, and 60.5% (52.3-68.6) among MDR-TB cases. The estimated global burden is 1.4 million new PZA resistant TB cases annually, about 270,000 in MDR-TB patients. Among 1,815 phenotypically resistant isolates, 608 unique SNPs occurred at 397 distinct positions throughout the pncA gene. Interpretation PZA resistance is ubiquitous, with an estimated one in six incident TB cases and more than half of all MDR-TB cases resistant to PZA globally. The diversity of SNPs across the pncA gene complicates the development of rapid molecular diagnostics. These findings caution against relying on PZA in current and future TB drug regimens, especially in MDR-TB patients.
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Affiliation(s)
- Michael G. Whitfield
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Heidi M. Soeters
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Robin M. Warren
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
- * E-mail:
| | - Talita York
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Samantha L. Sampson
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Elizabeth M. Streicher
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Paul D. van Helden
- SA MRC Centre for TB Research, Stellenbosch University, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa
- Division of Molecular Biology and Human Genetics, Stellenbosch University, South Africa
- Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Annelies van Rie
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- International Health Unit, Epidemiology and Social Medicine, Faculty of Medicine, University of Antwerp, Antwerp, Belgium
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Systematic review of mutations in pyrazinamidase associated with pyrazinamide resistance in Mycobacterium tuberculosis clinical isolates. Antimicrob Agents Chemother 2015; 59:5267-77. [PMID: 26077261 DOI: 10.1128/aac.00204-15] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/09/2015] [Indexed: 12/23/2022] Open
Abstract
Pyrazinamide (PZA) is an important first-line drug in the treatment of tuberculosis (TB) and of significant interest to the HIV-infected community due to the prevalence of TB-HIV coinfection in some regions of the world. The mechanism of resistance to PZA is unlike that of any other anti-TB drug. The gene pncA, encoding pyrazinamidase (PZase), is associated with resistance to PZA. However, because single mutations in PZase have a low prevalence, the individual sensitivities are low. Hundreds of distinct mutations in the enzyme have been associated with resistance, while some only appear in susceptible isolates. This makes interpretation of molecular testing difficult and often leads to the simplification that any PZase mutation causes resistance. This systematic review reports a comprehensive global list of mutations observed in PZase and its promoter region in clinical strains, their phenotypic association, their global frequencies and diversity, the method of phenotypic determination, their MIC values when given, and the method of MIC determination and assesses the strength of the association between mutations and phenotypic resistance to PZA. In this systematic review, we report global statistics for 641 mutations in 171 (of 187) codons from 2,760 resistant strains and 96 mutations from 3,329 susceptible strains reported in 61 studies. For diagnostics, individual mutations (or any subset) were not sufficiently sensitive. Assuming similar error profiles of the 5 phenotyping platforms included in this study, the entire enzyme and its promoter provide a combined estimated sensitivity of 83%. This review highlights the need for identification of an alternative mechanism(s) of resistance, at least for the unexplained 17% of cases.
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Pyrazinamide susceptibility testing in Mycobacterium tuberculosis: a systematic review with meta-analyses. Antimicrob Agents Chemother 2011; 55:4499-505. [PMID: 21768515 DOI: 10.1128/aac.00630-11] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Standard culture-based testing of the susceptibility of Mycobacterium tuberculosis to pyrazinamide is difficult to perform. This systematic review with meta-analyses evaluated the roles of molecular assays targeting pncA and of pyrazinamidase assays. PubMed and Embase were searched for relevant publications in English. Sensitivity and specificity were estimated in bivariate random-effects models. Of 128 articles identified, 73 sets of data involving culture isolates were initially included in meta-analyses. Summary estimates of sensitivity and specificity, respectively, were 87% and 93% for PCR-DNA sequencing (n = 29), 75% and 95% for PCR-single-stranded conformation polymorphism (SSCP) (n = 5), 96% and 97% for a mixture of other molecular assays (n = 6), and 89% and 97% for pyrazinamidase assays using the Wayne method (n = 33). The median prevalence (range) of pyrazinamide resistance was 51% (31% to 89%) in multidrug-resistant M. tuberculosis isolates and 5% (0% to 9%) in non-multidrug-resistant isolates. Excluding studies with possibly considerable false resistance in the reference assay gave the following estimates of sensitivity and specificity, respectively: 92% and 93% for PCR-DNA sequencing (n = 20), 98% and 96% for other molecular assays (n = 5), and 91% and 97% for the Wayne assay (n = 27). The Wayne assay had significant funnel plot asymmetry, so the test performance might have been overestimated. Considering the prevalence of pyrazinamide resistance in different clinical settings, PCR-DNA sequencing, and possibly other molecular assays targeting pncA, can detect pyrazinamide resistance in multidrug-resistant M. tuberculosis isolates, with predictive values largely exceeding 90%, and rule out pyrazinamide resistance in non-multidrug-resistant isolates, with predictive values exceeding 99%. Molecular assays are probably the way forward for detecting pyrazinamide resistance.
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Peruvian and globally reported amino acid substitutions on the Mycobacterium tuberculosis pyrazinamidase suggest a conserved pattern of mutations associated to pyrazinamide resistance. INFECTION GENETICS AND EVOLUTION 2009; 10:346-9. [PMID: 19963078 DOI: 10.1016/j.meegid.2009.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 11/28/2009] [Accepted: 11/30/2009] [Indexed: 11/15/2022]
Abstract
Resistance to pyrazinamide in Mycobacterium tuberculosis is usually associated with a reduction of pyrazinamidase activity caused by mutations in pncA, the pyrazinamidase coding gene. Pyrazinamidase is a hydrolase that converts pyrazinamide, the antituberculous drug against the latent stage, to the active compound, pyrazinoic acid. To better understand the relationship between pncA mutations and pyrazinamide resistance, it is necessary to analyze the distribution of pncA mutations from pyrazinamide resistant strains. We determined the distribution of Peruvian and globally reported pncA missense mutations from M. tuberculosis clinical isolates resistant to pyrazinamide. The distributions of the single amino acid substitutions were compared at the secondary structure domains level. The distribution of the Peruvian mutations followed a similar pattern as the mutations reported globally. A consensus clustering of mutations was observed in hot-spot regions located in the metal coordination site and to a lesser extent in the active site of the enzyme. The data was not able to reject the null hypothesis that both distributions are similar, suggesting that pncA mutations associated to pyrazinamide resistance in M. tuberculosis, follow a conserved pattern responsible to impair the pyrazinamidase activity.
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Sputum PCR-single-strand conformational polymorphism test for same-day detection of pyrazinamide resistance in tuberculosis patients. J Clin Microbiol 2009; 47:2937-43. [PMID: 19535526 DOI: 10.1128/jcm.01594-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pyrazinamide is a first-line drug for treating tuberculosis, but pyrazinamide resistance testing is usually too slow to guide initial therapy, so some patients receive inappropriate therapy. We therefore aimed to optimize and evaluate a rapid molecular test for tuberculosis drug resistance to pyrazinamide. Tuberculosis PCR-single-strand conformational polymorphism (PCR-SSCP) was optimized to test for mutations causing pyrazinamide resistance directly from sputum samples and Mycobacterium tuberculosis isolates. The reliability of PCR-SSCP tests for sputum samples (n = 65) and Mycobacterium tuberculosis isolates (n = 185) from 147 patients was compared with four tests for pyrazinamide resistance: Bactec-460 automated culture, the Wayne biochemical test, DNA sequencing for pncA mutations, and traditional microbiological broth culture. PCR-SSCP provided interpretable results for 96% (46/48) of microscopy-positive sputum samples, 76% (13/17) of microscopy-negative sputum samples, and 100% of Mycobacterium tuberculosis isolates. There was 100% agreement between PCR-SSCP results from sputum samples and Mycobacterium tuberculosis isolates and 100% concordance between 50 blinded PCR-SSCP rereadings by three observers. PCR-SSCP agreement with the four other tests for pyrazinamide resistance varied from 89 to 97%. This was similar to how frequently the four other tests for pyrazinamide resistance agreed with each other: 90 to 94% for Bactec-460, 90 to 95% for Wayne, 92 to 95% for sequencing, and 91 to 95% for broth culture. PCR-SSCP took less than 24 hours and cost approximately $3 to $6, in contrast with the other assays, which took 3 to 14 weeks and cost $7 to $47. In conclusion, PCR-SSCP is a relatively reliable, rapid, and inexpensive test for pyrazinamide resistance that indicates which patients should receive pyrazinamide from the start of therapy, potentially preventing months of inappropriate treatment.
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Effect of pyrazinamidase activity on pyrazinamide resistance in Mycobacterium tuberculosis. Tuberculosis (Edinb) 2009; 89:109-13. [PMID: 19249243 DOI: 10.1016/j.tube.2009.01.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 01/12/2009] [Accepted: 01/14/2009] [Indexed: 11/20/2022]
Abstract
Resistance of Mycobacterium tuberculosis to pyrazinamide is associated with mutations in the pncA gene, which codes for pyrazinamidase. The association between the enzymatic activity of mutated pyrazinamidases and the level of pyrazinamide resistance remains poorly understood. Twelve M. tuberculosis clinical isolates resistant to pyrazinamide were selected based on Wayne activity and localization of pyrazinamidase mutation. Recombinant pyrazinamidases were expressed and tested for their kinetic parameters (activity, k(cat), K(m), and efficiency). Pyrazinamide resistance level was measured by Bactec-460TB and 7H9 culture. The linear correlation between the resistance level and the kinetic parameters of the corresponding mutated pyrazinamidase was calculated. The enzymatic activity and efficiency of the mutated pyrazinamidases varied with the site of mutation and ranged widely from low to high levels close to the corresponding of the wild type enzyme. The level of resistance was significantly associated with pyrazinamidase activity and efficiency, but only 27.3% of its statistical variability was explained. Although pyrazinamidase mutations are indeed associated with resistance, the loss of pyrazinamidase activity and efficiency as assessed in the recombinant mutated enzymes is not sufficient to explain a high variability of the level of pyrazinamide resistance, suggesting that complementary mechanisms for pyrazinamide resistance in M. tuberculosis with mutations in pncA are more important than currently thought.
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McCammon MT, Gillette JS, Thomas DP, Ramaswamy SV, Rosas II, Graviss EA, Vijg J, Quitugua TN. Detection by denaturing gradient gel electrophoresis of pncA mutations associated with pyrazinamide resistance in Mycobacterium tuberculosis isolates from the United States-Mexico border region. Antimicrob Agents Chemother 2005; 49:2210-7. [PMID: 15917514 PMCID: PMC1140546 DOI: 10.1128/aac.49.6.2210-2217.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 01/12/2005] [Accepted: 02/08/2005] [Indexed: 11/20/2022] Open
Abstract
Denaturing gradient gel electrophoresis (DGGE) was used to probe for mutations associated with pyrazinamide (PZA) resistance in the pncA gene of Mycobacterium tuberculosis. DGGE scans for mutations across large regions of DNA and rivals sequencing in its ability to detect DNA alterations. Specific mutations can often be recognized by their characteristic denaturation pattern, which serves as a molecular fingerprint. Five PCR target fragments were designed to scan for DNA alterations across 600 bp of pncA in 181 M. tuberculosis isolates from patients residing in the U.S-Mexico border states of Texas and Tamaulipas, respectively. A region of pncA was observed with a high GC content and a melting temperature approaching 90 degrees C that was initially refractory to denaturation, and a DGGE target fragment was specifically designed to detect mutations in this region. DGGE detected pncA mutations in 82 of 83 PZA-resistant isolates. By contrast, only 1 of 98 PZA-susceptible isolates harbored a detectable DNA alteration. The pncA gene was sequenced from 41 isolates, and 32 DNA alterations in 32 PZA-resistant isolates were identified, including 11 new mutations. DGGE also detected nine isolates whose susceptibility to PZA appeared to be incorrect, and DNA sequencing confirmed these apparent errors in drug susceptibility testing. These results demonstrate the power and usefulness of DGGE in detecting mutations associated with PZA resistance in M. tuberculosis.
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Affiliation(s)
- Mark T McCammon
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, STCBM Building, 15355 Lambda Dr., San Antonio, TX 78245, USA.
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O'Sullivan DM, McHugh TD, Gillespie SH. Analysis of rpoB and pncA mutations in the published literature: an insight into the role of oxidative stress in Mycobacterium tuberculosis evolution? J Antimicrob Chemother 2005; 55:674-9. [PMID: 15814606 DOI: 10.1093/jac/dki069] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION It is perceived wisdom that within the host macrophage, Mycobacterium tuberculosis frequently encounters oxidative stress. Exposure of bacteria to reactive oxygen intermediates can have a mutagenic effect on the DNA. Various mutations are thought to arise as a consequence, including the oxidation of guanine residues, leading to G?C-->T?A substitution, and oxidation of cytosine resulting in a G?C-->A?T substitution. METHODS We measured the relative contribution of oxidative stress by recording the percentage of single nucleotide substitutions reported in the genes rpoB and pncA that confer resistance to the antimicrobials rifampicin and pyrazinamide, respectively, and determined whether there is an excess of G?C-->T?A or G?C-->A?T substitutions. RESULTS Out of 840 clinical isolates reported with single nucleotide mutations in the rpoB gene, 67% were G?C-->A?T changes, and 3% were G?C-->T?A substitutions. These figures were compared to the pncA gene, where out of 114 isolates, 30% of the single nucleotide mutations were G?C-->A?T transitions and 9% were G?C-->T?A changes. CONCLUSIONS While there is an excess of G?C-->A?T changes in the rpoB gene, this was not the case in the pncA gene. Fifty-three percent of mutations within the rpoB gene were C-->T mutations of the type S531L. Although this mutation gives a fitness disadvantage, it is less than other common mutations, so it is more likely that that fitness is the determinant of surviving mutation rather than oxidative stress because of the small numbers of other C-->T and G-->A mutations at other sites (12%). There was no evidence of oxygen free radicals damaging the guanine bases in either gene.
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Affiliation(s)
- Denise M O'Sullivan
- Centre for Medical Microbiology, Department of Infection, Royal Free & University College Medical School, Royal Free Campus, University College London, Rowland Hill Street, London NW3 2PF, UK
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