101
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Walter ND, Strong M, Belknap R, Ordway DJ, Daley CL, Chan ED. Translating basic science insight into public health action for multidrug- and extensively drug-resistant tuberculosis. Respirology 2012; 17:772-91. [PMID: 22458269 PMCID: PMC4540333 DOI: 10.1111/j.1440-1843.2012.02176.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multidrug (MDR)- and extensively drug-resistant (XDR) tuberculosis (TB) impose a heavy toll of human suffering and social costs. Controlling drug-resistant TB is a complex global public health challenge. Basic science advances including elucidation of the genetic basis of resistance have enabled development of new assays that are transforming the diagnosis of MDR-TB. Molecular epidemiological approaches have provided new insights into the natural history of TB with important implications for drug resistance. In the future, progress in understanding Mycobacterium tuberculosis strain-specific human immune responses, integration of systems biology approaches with traditional epidemiology and insight into the biology of mycobacterial persistence have potential to be translated into new tools for diagnosis and treatment of MDR- and XDR-TB. We review recent basic sciences developments that have contributed or may contribute to improved public health response.
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Affiliation(s)
- Nicholas D Walter
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, Colorado, USA.
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102
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Abstract
Children with presumed tuberculosis who are in contact with a multidrug-resistant source case should be treated according to the drug susceptibility of the source case's isolate. However, it is important to obtain a microbiologic diagnosis as it is possible for the child to have a different susceptibility profile to the source case. We present 2 such cases.
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103
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Gegia M, Cohen T, Kalandadze I, Vashakidze L, Furin J. Outcomes among tuberculosis patients with isoniazid resistance in Georgia, 2007-2009. Int J Tuberc Lung Dis 2012; 16:812-6. [PMID: 22507372 DOI: 10.5588/ijtld.11.0637] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The optimal management strategy for patients with isoniazid (INH) monoresistant forms of tuberculosis (TB) has been widely debated. The current daily 9-month regimen of rifampin, pyrazinamide and ethambutol was established based largely on trials in settings with low TB rates and low rates of drug resistance. OBJECTIVE To explore the outcomes of patients with INH-monoresistant TB in the country of Georgia, a setting with both high TB rates and drug-resistant forms of the disease. METHODS Retrospective record review of all patients diagnosed with smear-positive pulmonary TB resistant to either INH or INH+SM (streptomycin) in Georgia between 2007 and 2009. RESULTS Of 8752 patients with pulmonary TB registered in Georgia, 909 were found to have INH or INH+SM resistance. Treatment outcomes were relatively poor in this group, with only 71% treatment success. Outcomes were significantly worse among patients with older age and a history of previous treatment. CONCLUSIONS INH or INH+SM resistance in pulmonary TB patients in Georgia is common. The low rates of treatment success suggest the need for an improved treatment regimen for patients with resistance to these first-line drugs; this need is particularly pronounced among the subset of patients with a history of previous treatment.
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Affiliation(s)
- M Gegia
- The National Center for TB and Lung Diseases, Georgia, Tbilisi, Georgia
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104
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Seddon JA, Godfrey-Faussett P, Hesseling AC, Gie RP, Beyers N, Schaaf HS. Management of children exposed to multidrug-resistant Mycobacterium tuberculosis. THE LANCET. INFECTIOUS DISEASES 2012; 12:469-79. [PMID: 22373591 DOI: 10.1016/s1473-3099(11)70366-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Children exposed to multidrug-resistant (MDR) Mycobacterium tuberculosis are at risk of developing MDR tuberculosis. Where treatment is available, it is lengthy, expensive, and associated with poor adherence and notable morbidity and mortality. Preventive treatment effectively lowers the risk of disease progression for contacts of individuals with drug-susceptible tuberculosis, but this strategy is poorly studied for contacts of people with MDR tuberculosis. In this Review we discuss the management of child contacts of source cases with MDR tuberculosis. We pay particular attention to assessment, existing international guidelines, possible preventive treatments, rationales for different management strategies, and the interaction with and implications of HIV infection.
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Affiliation(s)
- James A Seddon
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK .
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105
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Mycobacterium tuberculosis population structure determines the outcome of genetics-based second-line drug resistance testing. Antimicrob Agents Chemother 2012; 56:2420-7. [PMID: 22330913 DOI: 10.1128/aac.05905-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The global emergence of multidrug-resistant tuberculosis has highlighted the need for the development of rapid tests to identify resistance to second-line antituberculosis drugs. Resistance to fluoroquinolones and aminoglycosides develops through nonsynonymous single nucleotide polymorphisms in the gyrA and gyrB genes and the rrs gene, respectively. Using DNA sequencing as the gold standard for the detection of mutations conferring resistance, in conjunction with spoligotyping, we demonstrated heteroresistance in 25% and 16.3% of Mycobacterium tuberculosis isolates resistant to ofloxacin and amikacin, respectively. Characterization of follow-up isolates from the same patients showed that the population structure of clones may change during treatment, suggesting different phases in the emergence of resistance. The presence of underlying mutant clones was identified in isolates which failed to show a correlation between phenotypic resistance and mutation in the gyrA or rrs gene. These clones harbored previously described mutations in either the gyrA or rrs gene, suggesting that rare mutations conferring resistance to ofloxacin or amikacin may not be as important as was previously thought. We concluded that the absence of a correlation between genotypic and phenotypic resistance implies an early phase in the emergence of resistance within the patient. Thus, the diagnostic utility of genetics-based drug susceptibility tests will depend on the proportion of patients whose bacilli are in the process of acquiring resistance in the study setting. These data have implications for the interpretation of molecular and microbiological diagnostic tests for patients with drug-susceptible and drug-resistant tuberculosis who fail to respond to treatment and for those with discordant results.
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106
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On the pathogenesis of post primary tuberculosis: The role of bronchial obstruction in the pathogenesis of cavities. Tuberculosis (Edinb) 2011; 91 Suppl 1:S6-10. [DOI: 10.1016/j.tube.2011.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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107
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Prevalence and implications of multiple-strain infections. THE LANCET. INFECTIOUS DISEASES 2011; 11:868-78. [DOI: 10.1016/s1473-3099(11)70241-9] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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108
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van der Werf MJ, Langendam MW, Huitric E, Manissero D. Multidrug resistance after inappropriate tuberculosis treatment: a meta-analysis. Eur Respir J 2011; 39:1511-9. [PMID: 22005918 PMCID: PMC3365250 DOI: 10.1183/09031936.00125711] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We conducted a systematic review and meta-analysis to assess the evidence for the postulation that inappropriate tuberculosis (TB) regimens are a risk for development of multidrug-resistant (MDR)-TB. MEDLINE, EMBASE and other databases were searched for relevant articles in January 2011. Cohort studies including TB patients who received treatment were selected and data on treatment regimen, drug susceptibility testing results and genotyping results before treatment and at failure or relapse were abstracted from the articles. Four studies were included in the systematic review and two were included in the meta-analysis. In these two studies the risk of developing MDR-TB in patients who failed treatment and used an inappropriate treatment regimen was increased 27-fold (RR 26.7, 95% CI 5.0-141.7) when compared with individuals who received an appropriate treatment regimen. This review provides evidence that supports the general opinion that the development of MDR-TB can be caused by inadequate treatment, given the drug susceptibility pattern of the Mycobacterium tuberculosis bacilli. It should be noted that only two studies provided data for the meta-analysis. The information can be used to advocate for adequate treatment for patients based on drug resistance profiles.
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109
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Systematic survey of clonal complexity in tuberculosis at a populational level and detailed characterization of the isolates involved. J Clin Microbiol 2011; 49:4131-7. [PMID: 21956991 DOI: 10.1128/jcm.05203-11] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clonally complex infections by Mycobacterium tuberculosis are progressively more accepted. Studies of their dimension in epidemiological scenarios where the infective pressure is not high are scarce. Our study systematically searched for clonally complex infections (mixed infections by more than one strain and simultaneous presence of clonal variants) by applying mycobacterial interspersed repetitive-unit (MIRU)-variable-number tandem-repeat (VNTR) analysis to M. tuberculosis isolates from two population-based samples of respiratory (703 cases) and respiratory-extrapulmonary (R+E) tuberculosis (TB) cases (71 cases) in a context of moderate TB incidence. Clonally complex infections were found in 11 (1.6%) of the respiratory TB cases and in 10 (14.1%) of those with R+E TB. Among the 21 cases with clonally complex TB, 9 were infected by 2 independent strains and the remaining 12 showed the simultaneous presence of 2 to 3 clonal variants. For the 10 R+E TB cases with clonally complex infections, compartmentalization (different compositions of strains/clonal variants in independent infected sites) was found in 9 of them. All the strains/clonal variants were also genotyped by IS6110-based restriction fragment length polymorphism analysis, which split two MIRU-defined clonal variants, although in general, it showed a lower discriminatory power to identify the clonal heterogeneity revealed by MIRU-VNTR analysis. The comparative analysis of IS6110 insertion sites between coinfecting clonal variants showed differences in the genes coding for a cutinase, a PPE family protein, and two conserved hypothetical proteins. Diagnostic delay, existence of previous TB, risk for overexposure, and clustered/orphan status of the involved strains were analyzed to propose possible explanations for the cases with clonally complex infections. Our study characterizes in detail all the clonally complex infections by M. tuberculosis found in a systematic survey and contributes to the characterization that these phenomena can be found to an extent higher than expected, even in an unselected population-based sample lacking high infective pressure.
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110
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Mariam SH, Werngren J, Aronsson J, Hoffner S, Andersson DI. Dynamics of antibiotic resistant Mycobacterium tuberculosis during long-term infection and antibiotic treatment. PLoS One 2011; 6:e21147. [PMID: 21698208 PMCID: PMC3116863 DOI: 10.1371/journal.pone.0021147] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 05/20/2011] [Indexed: 11/19/2022] Open
Abstract
For an infecting bacterium the human body provides several potential ecological niches with both internally (e.g. host immunity) and externally (e.g. antibiotic use) imposed growth restrictions that are expected to drive adaptive evolution in the bacterium, including the development of antibiotic resistance. To determine the extent and pattern of heterogeneity generated in a bacterial population during long-term antibiotic treatment, we examined in a monoclonal Mycobacterium tuberculosis infection antibiotic resistant mutants isolated from one patient during a 9-years period. There was a progressive accumulation of resistance mutations in the infecting clone. Furthermore, apparent clonal sweeps as well as co-existence of different resistant mutants were observed during this time, demonstrating that during treatment there is a high degree of dynamics in the bacterial population. These findings have important implications for diagnostics and treatment of drug resistant tuberculosis infections.
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Affiliation(s)
- Solomon H. Mariam
- Swedish Institute for Infectious Disease Control, Solna, Sweden
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Jim Werngren
- Swedish Institute for Infectious Disease Control, Solna, Sweden
| | - Joakim Aronsson
- Department of Infectious Diseases, County Hospital Ryhov, Jönköping, Sweden
| | - Sven Hoffner
- Swedish Institute for Infectious Disease Control, Solna, Sweden
| | - Dan I. Andersson
- Department of Infectious Diseases, County Hospital Ryhov, Jönköping, Sweden
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
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111
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Models to understand the population-level impact of mixed strain M. tuberculosis infections. J Theor Biol 2011; 280:88-100. [PMID: 21514304 DOI: 10.1016/j.jtbi.2011.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Revised: 03/26/2011] [Accepted: 04/08/2011] [Indexed: 11/23/2022]
Abstract
Over the past decade, numerous studies have identified tuberculosis patients in whom more than one distinct strain of Mycobacterium tuberculosis is present. While it has been shown that these mixed strain infections can reduce the probability of treatment success for individuals simultaneously harboring both drug-sensitive and drug-resistant strains, it is not yet known if and how this phenomenon impacts the long-term dynamics for tuberculosis within communities. Strain-specific differences in immunogenicity and associations with drug resistance suggest that a better understanding of how strains compete within hosts will be necessary to project the effects of mixed strain infections on the future burden of drug-sensitive and drug-resistant tuberculosis. In this paper, we develop a modeling framework that allows us to investigate mechanisms of strain competition within hosts and to assess the long-term effects of such competition on the ecology of strains in a population. These models permit us to systematically evaluate the importance of unknown parameters and to suggest priority areas for future experimental research. Despite the current scarcity of data to inform the values of several model parameters, we are able to draw important qualitative conclusions from this work. We find that mixed strain infections may promote the coexistence of drug-sensitive and drug-resistant strains in two ways. First, mixed strain infections allow a strain with a lower basic reproductive number to persist in a population where it would otherwise be outcompeted if has competitive advantages within a co-infected host. Second, some individuals progressing to phenotypically drug-sensitive tuberculosis from a state of mixed drug-sensitive and drug-resistant infection may retain small subpopulations of drug-resistant bacteria that can flourish once the host is treated with antibiotics. We propose that these types of mixed infections, by increasing the ability of low fitness drug-resistant strains to persist, may provide opportunities for compensatory mutations to accumulate and for relatively fit, highly drug-resistant strains of M. tuberculosis to emerge.
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112
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Wang JY, Hsu HL, Yu MC, Chiang CY, Yu FL, Yu CJ, Lee LN, Yang PC. Mixed infection with Beijing and non-Beijing strains in pulmonary tuberculosis in Taiwan: prevalence, risk factors, and dominant strain. Clin Microbiol Infect 2010; 17:1239-45. [PMID: 20946415 DOI: 10.1111/j.1469-0691.2010.03401.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Patients with pulmonary tuberculosis (TB) can be simultaneously infected with different strains of Mycobacterium tuberculosis (mixed infection). We investigated the prevalence and risk factors of mixed infection by Beijing and non-Beijing strains in pulmonary TB patients in Taiwan. We developed a quantitative PCR method to simultaneously detect the presence of Beijing and non-Beijing strains. A total of 868 pretreatment samples (from 868 patients), including 563 sputum samples smear-positive for acid-fast bacilli and 305 liquid medium samples culture-positive for mycobacteria, were tested. Medical records of patients with culture-confirmed pulmonary TB were reviewed. The detection limit of our quantitative PCR method was five copies of target sequences. With mycobacterial culture result as the reference standard, the sensitivity and specificity of our quantitative PCR method were 95% and 98%, respectively. M. tuberculosis strains were isolated in 466 samples, of which 231 (49.6%) were infected with a Beijing strain. Another 14 patients (3.0%) had mixed infection, with the Beijing strain being the dominant strain in 13 (93%). Age <25 years with pulmonary cavities was associated with mixed infection. In patients infected with non-Beijing strains, the bacterial load of non-Beijing strains was lower among those with mixed infection than among those without. Our quantitative PCR method was accurate in detecting Beijing and non-Beijing strains in smear-positive sputum and culture-positive liquid medium samples. Mixed infection was present in pulmonary TB patients (3.0%), especially in those aged <25 years with pulmonary cavities. Beijing strains seem to be more dominant than non-Beijing strains in patients with mixed infection.
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Affiliation(s)
- J-Y Wang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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113
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Mixed-strain Mycobacterium tuberculosis infections among patients dying in a hospital in KwaZulu-Natal, South Africa. J Clin Microbiol 2010; 49:385-8. [PMID: 20980576 DOI: 10.1128/jcm.01378-10] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We performed spoligotyping and 24-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing on M. tuberculosis culture-positive biopsy specimens collected from adults dying in a hospital in KwaZulu-Natal. Of 56 culture-positive samples genotyped, we detected mixed strains in five (9%) and clonal heterogeneity in an additional four (7%).
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114
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Mixed infection with Beijing and non-Beijing strains and drug resistance pattern of Mycobacterium tuberculosis. J Clin Microbiol 2010; 48:4474-80. [PMID: 20980571 DOI: 10.1128/jcm.00930-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mixed infection with Beijing and non-Beijing strains of Mycobacterium tuberculosis has been reported and has been suggested to mediate elevation of the reinfection rate in regions with a high incidence of tuberculosis (TB). To evaluate the prevalence of infection with both Beijing and non-Beijing strains of M. tuberculosis in eastern Taiwan, the region with the highest TB incidence in Taiwan, 185 active pulmonary TB patients were enrolled at Tzu Chi General Hospital from October 2007 to September 2008. A modified multiplex PCR method was developed to distinguish Beijing and non-Beijing strains directly using the sputum of patients. Of the 185 patients, 46.5% were infected with a Beijing strain, 42.2% were infected with a non-Beijing strain, and 11.3% were infected with both strain types. Notably, mixed infection with both strain types was not associated with TB treatment history or the high-incidence race group, aborigines. In addition, the incidence rate of mixed infection before treatment with anti-TB medication was as high as that in patients with a history of anti-TB treatment. Further analysis of antibiotic susceptibility revealed that Beijing strains alone had the highest multidrug resistance rate (17.5%), mixed infection had the highest rate of resistance to at least one drug (23.8%), and non-Beijing strains had the highest rate of sensitivity to all drugs (79.5%), implying that Beijing strains are predominant in the development of drug resistance in tuberculosis.
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115
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Molecular detection of mixed infections of Mycobacterium tuberculosis strains in sputum samples from patients in Karonga District, Malawi. J Clin Microbiol 2010; 48:4512-8. [PMID: 20962138 DOI: 10.1128/jcm.01683-10] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The occurrence of mixed infections of Mycobacterium tuberculosis is no longer disputed. However, their frequency, and the impact they may have on our understanding of tuberculosis (TB) pathogenesis and epidemiology, remains undetermined. Most previous studies of frequency applied genotyping techniques to cultured M. tuberculosis isolates and found mixed infections to be rare. PCR-based techniques may be more sensitive for detecting multiple M. tuberculosis strains and can be applied to sputum. To date, one study in South Africa has used a PCR approach and suggested that mixed infection could be common. We investigated mixed infections in northern Malawi using two lineage-specific PCR assays targeting the Latin American-Mediterranean (LAM) and Beijing lineages. Compared with spoligotyping, the specificity and sensitivity of both assays was 100%. From 160 culture-positive sputa, mixed LAM and non-LAM strains were detected in 4 sputa belonging to 2 (2.8%) patients. Both patients were HIV positive, with no history of TB. Cultured isolates from both patients showed only LAM by PCR and spoligotyping. In a set of 377 cultured isolates, 4 were mixed LAM and non-LAM. Only one showed evidence of more than one M. tuberculosis strain using IS6110-based restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping analyses. Corresponding sputa for the 4 isolates were unavailable. Mixed Beijing and non-Beijing strains were not detected in this study. Mixed infections appear to be rare in our setting and are unlikely to affect findings based on DNA fingerprinting data. Molecular methods, which avoid the selective nature of culture and target distinct strains, are well suited to detection of mixed infections.
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116
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Dheda K, Warren RM, Zumla A, Grobusch MP. Extensively Drug-resistant Tuberculosis: Epidemiology and Management Challenges. Infect Dis Clin North Am 2010; 24:705-25. [DOI: 10.1016/j.idc.2010.05.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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117
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Mycobacterial biofilms facilitate horizontal DNA transfer between strains of Mycobacterium smegmatis. J Bacteriol 2010; 192:5134-42. [PMID: 20675473 DOI: 10.1128/jb.00650-10] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Conjugal transfer of chromosomal DNA between strains of Mycobacterium smegmatis occurs by a novel mechanism. In a transposon mutagenesis screen, three transfer-defective insertions were mapped to the lsr2 gene of the donor strain mc(2)155. Because lsr2 encodes a nonspecific DNA-binding protein, mutations of lsr2 give rise to a variety of phenotypes, including an inability to form biofilms. In this study, we show that efficient DNA transfer between strains of M. smegmatis occurs in a mixed biofilm and that the process requires expression of lsr2 in the donor but not in the recipient strain. Testing cells from different strata of standing cultures showed that transfer occurred predominantly at the biofilm air-liquid interface, as other strata containing higher cell densities produced very few transconjugants. These data suggest that the biofilm plays a role beyond mere facilitation of cell-cell contact. Surprisingly, we found that under standard assay conditions the recipient strain does not form a biofilm. Taking these results together, we conclude that for transfer to occur, the recipient strain is actively recruited into the biofilm. In support of this idea, we show that donor and recipient cells are present in almost equal numbers in biofilms that produce transconjugants. Our demonstration of genetic exchange between mycobacteria in a mixed biofilm suggests that conjugation occurs in the environment. Since biofilms are considered to be the predominant natural microhabitat for bacteria, our finding emphasizes the importance of studying biological and physical processes that occur between cells in mixed biofilms.
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118
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Abstract
We performed the first studies of analytic sensitivity, analytic specificity, and dynamic range for the new Xpert MTB/RIF assay, a nucleic acid amplification-based diagnostic system that detects Mycobacterium tuberculosis and rifampin (RIF) resistance in under 2 h. The sensitivity of the assay was tested with 79 phylogenetically and geographically diverse M. tuberculosis isolates, including 42 drug-susceptible isolates and 37 RIF-resistant isolates containing 13 different rpoB mutations or mutation combinations. The specificity of the assay was tested with 89 nontuberculosis bacteria, fungi, and viruses. The Xpert MTB/RIF assay correctly identified all 79 M. tuberculosis isolates and correctly excluded all 89 nontuberculosis isolates. RIF resistance was correctly identified in all 37 resistant isolates and in none of the 42 susceptible isolates. Dynamic range was assessed by adding 10(2) to 10(7) CFU of M. tuberculosis into M. tuberculosis-negative sputum samples. The assay showed a log-linear relationship between cycle threshold and input CFU over the entire concentration range. Resistance detection in the presence of different mixtures of RIF-resistant and RIF-susceptible DNA was assessed. Resistance detection was dependent on the particular mutation and required between 65% and 100% mutant DNA to be present in the sample for 95% certainty of resistance detection. Finally, we studied whether assay specificity could be affected by cross-contaminating amplicons generated by the GenoType MTBDRplus assay. M. tuberculosis was not detected until at least 10(8) copies of an MTBDRplus amplicon were spiked into 1 ml of sputum, suggesting that false-positive results would be unlikely to occur.
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119
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Gandhi NR, Nunn P, Dheda K, Schaaf HS, Zignol M, van Soolingen D, Jensen P, Bayona J. Multidrug-resistant and extensively drug-resistant tuberculosis: a threat to global control of tuberculosis. Lancet 2010; 375:1830-43. [PMID: 20488523 DOI: 10.1016/s0140-6736(10)60410-2] [Citation(s) in RCA: 698] [Impact Index Per Article: 49.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Although progress has been made to reduce global incidence of drug-susceptible tuberculosis, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis during the past decade threatens to undermine these advances. However, countries are responding far too slowly. Of the estimated 440,000 cases of MDR tuberculosis that occurred in 2008, only 7% were identified and reported to WHO. Of these cases, only a fifth were treated according to WHO standards. Although treatment of MDR and XDR tuberculosis is possible with currently available diagnostic techniques and drugs, the treatment course is substantially more costly and laborious than for drug-susceptible tuberculosis, with higher rates of treatment failure and mortality. Nonetheless, a few countries provide examples of how existing technologies can be used to reverse the epidemic of MDR tuberculosis within a decade. Major improvements in laboratory capacity, infection control, performance of tuberculosis control programmes, and treatment regimens for both drug-susceptible and drug-resistant disease will be needed, together with a massive scale-up in diagnosis and treatment of MDR and XDR tuberculosis to prevent drug-resistant strains from becoming the dominant form of tuberculosis. New diagnostic tests and drugs are likely to become available during the next few years and should accelerate control of MDR and XDR tuberculosis. Equally important, especially in the highest-burden countries of India, China, and Russia, will be a commitment to tuberculosis control including improvements in national policies and health systems that remove financial barriers to treatment, encourage rational drug use, and create the infrastructure necessary to manage MDR tuberculosis on a national scale.
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Affiliation(s)
- Neel R Gandhi
- Department of Medicine, Albert Einstein College of Medicine and Montefiore Medical Center, New York, NY 10467, USA.
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120
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Shin SS, Keshavjee S, Gelmanova IY, Atwood S, Franke MF, Mishustin SP, Strelis AK, Andreev YG, Pasechnikov AD, Barnashov A, Tonkel TP, Cohen T. Development of extensively drug-resistant tuberculosis during multidrug-resistant tuberculosis treatment. Am J Respir Crit Care Med 2010; 182:426-32. [PMID: 20413630 DOI: 10.1164/rccm.200911-1768oc] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Extensively drug-resistant (XDR) tuberculosis (TB) may arise in individuals on treatment for multidrug-resistant (MDR) TB. Preventing this amplification of resistance will likely improve clinical outcomes and delay the secondary spread of XDR-TB. OBJECTIVES To measure the proportion of individuals that develops XDR-TB during the course of MDR-TB treatment, and to identify those factors associated with the development of XDR. METHODS We performed a retrospective analysis of 608 consecutive patients with documented MDR-TB who were started on MDR-TB treatment between September 10, 2000 and November 1, 2004 in the Tomsk Oblast TB Treatment Services in Western Siberia, Russian Federation. MEASUREMENTS AND MAIN RESULTS A total of 6% of patients were observed to develop XDR-TB while on MDR-TB treatment. These patients were significantly less likely to be cured or to complete treatment. Using Cox proportional hazard models, we found that the presence of bilateral and cavitary lesions was associated with a greater than threefold increase in hazard (adjusted hazard ratio [HR], 3.47; 95% confidence interval [CI], 1.32-9.14). Prior exposure to a second-line injectable antibiotic was associated with a greater than threefold increase in hazard (adjusted HR, 3.65; 95% CI, 1.81-7.37), and each additional month in which a patient failed to take at least 80% of their prescribed drugs was associated with nearly an additional 20% hazard of developing XDR-TB (adjusted HR, 1.17; 95% CI, 1.01-1.35). CONCLUSIONS Early and rapid diagnosis, timely initiation of appropriate therapy, and programmatic efforts to optimize treatment adherence during MDR-TB therapy are crucial to avoiding the generation of excess XDR-TB in MDR-TB treatment programs.
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Affiliation(s)
- Sonya S Shin
- Division of Global Health Equity, Brigham and Women's Hospital, Boston, MA 02115, USA.
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121
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Experiência da Rede Brasileira de Pesquisa em Tuberculose no desenvolvimento e avaliação de novos métodos de diagnóstico em tuberculose. REVISTA PORTUGUESA DE PNEUMOLOGIA 2010; 16SA:S67-76. [DOI: 10.1016/s0873-2159(15)30095-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Schaaf HS, Moll AP, Dheda K. Multidrug- and Extensively Drug-resistant Tuberculosis in Africa and South America: Epidemiology, Diagnosis and Management in Adults and Children. Clin Chest Med 2009; 30:667-83, vii-viii. [DOI: 10.1016/j.ccm.2009.08.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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123
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Outcomes after chemotherapy with WHO category II regimen in a population with high prevalence of drug resistant tuberculosis. PLoS One 2009; 4:e7954. [PMID: 19956770 PMCID: PMC2776350 DOI: 10.1371/journal.pone.0007954] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 10/20/2009] [Indexed: 11/19/2022] Open
Abstract
Standard short course chemotherapy is recommended by the World Health Organization to control tuberculosis worldwide. However, in settings with high drug resistance, first line standard regimens are linked with high treatment failure. We evaluated treatment outcomes after standardized chemotherapy with the WHO recommended category II retreatment regimen in a prison with a high prevalence of drug resistant tuberculosis (TB). A cohort of 233 culture positive TB patients was followed through smear microscopy, culture, drug susceptibility testing and DNA fingerprinting at baseline, after 3 months and at the end of treatment. Overall 172 patients (74%) became culture negative, while 43 (18%) remained positive at the end of treatment. Among those 43 cases, 58% of failures were determined to be due to treatment with an inadequate drug regimen and 42% to either an initial mixed infection or re-infection while under treatment. Overall, drug resistance amplification during treatment occurred in 3.4% of the patient cohort. This study demonstrates that treatment failure is linked to initial drug resistance, that amplification of drug resistance occurs, and that mixed infection and re-infection during standard treatment contribute to treatment failure in confined settings with high prevalence of drug resistance.
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124
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Mycobacterium tuberculosis strains with highly discordant rifampin susceptibility test results. J Clin Microbiol 2009; 47:3501-6. [PMID: 19759221 DOI: 10.1128/jcm.01209-09] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The objectives of this study were to investigate the origin of highly discordant rifampin (rifampicin) (RMP) drug susceptibility test results obtained for Mycobacterium tuberculosis strains during proficiency testing. Nine Supra-National Tuberculosis Reference Laboratories tested the RMP susceptibilities of 19 selected M. tuberculosis strains, using standard culture-based methods. The strains were classified as definitely resistant (R) (n = 6) or susceptible (S) (n = 2) or probably resistant (PR) (n = 8) or susceptible (PS) (n = 3) based on rpoB mutations and treatment outcome. All methods yielded a susceptible result for the two S and three PS strains lacking an rpoB mutation and a resistant result for one R strain with a Ser531Leu mutation and one PR strain with a double mutation. Although the remaining 12 R and PR strains had rpoB mutations (four Asp516Tyr, three Leu511Pro, two Leu533Pro, one each His526Leu/Ser, and one Ile572Phe), they were all susceptible by the radiometric Bactec 460TB or Bactec 960 MGIT methods. In contrast, only one was susceptible by the proportion method on Löwenstein-Jensen medium and two on Middlebrook 7H10 agar. Low-level but probably clinically relevant RMP resistance linked to specific rpoB mutations is easily missed by standard growth-based methods, particularly the automated broth-based systems. Further studies are required to confirm these findings, to determine the frequency of these low-level-resistant isolates, and to identify technical improvements that may identify such strains.
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125
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Andrews JR, Gandhi NR, Moodley P, Shah NS, Bohlken L, Moll AP, Pillay M, Friedland G, Sturm AW. Exogenous reinfection as a cause of multidrug-resistant and extensively drug-resistant tuberculosis in rural South Africa. J Infect Dis 2008; 198:1582-9. [PMID: 18847372 DOI: 10.1086/592991] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) are now major threats in areas of South Africa with a high prevalence of TB and human immunodeficiency virus (HIV) infection. The role of exogenous reinfection as a cause of MDR and XDR TB in these settings has not been determined. METHODS We reviewed data from patients with culture-positive TB who later developed MDR or XDR TB in Tugela Ferry, KwaZulu-Natal, South Africa during 2005-2006. We performed spoligotyping on initial isolates (obtained at the time of treatment initiation) and follow-up isolates obtained from these patients. RESULTS We identified 23 patients who developed MDR or XDR TB after being treated for less resistant TB between June 2005 and June 2006. Both initial and follow-up isolates were available for spoligotyping for 17 of these patients. In all cases, the follow-up isolates' spoligotypes differed from those of the initial isolate, indicating exogenous reinfection. Two genotypes (shared type [ST] 34 and ST 60, associated with MDR and XDR TB, respectively) were responsible for 85% of reinfections. All 17 patients had been hospitalized; all 15 whose HIV infection status was known were HIV-infected. CONCLUSIONS Exogenous reinfection is an important mechanism for the development of MDR and XDR TB. In addition to strengthening TB treatment programs, effective infection control strategies are urgently needed to reduce the transmission of MDR and XDR TB.
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Affiliation(s)
- Jason R Andrews
- Division of General Internal Medicine, University of California-San Francisco/San Francisco General Hospital, San Francisco, CA, USA
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126
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Colijn C, Cohen T, Murray M. Latent coinfection and the maintenance of strain diversity. Bull Math Biol 2008; 71:247-63. [PMID: 19082663 DOI: 10.1007/s11538-008-9361-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 07/10/2008] [Indexed: 11/26/2022]
Abstract
Technologies for strain differentiation and typing have made it possible to detect genetic diversity of pathogens, both within individual hosts and within communities. Coinfection of a host by more than one pathogen strain may affect the relative frequency of these strains at the population level through complex within- and between-host interactions; in infectious diseases that have a long latent period, interstrain competition during latency is likely to play an important role in disease dynamics. We show that SEIR models that include a class of latently coinfected individuals can have markedly different long-term dynamics than models without coinfection, and that coinfection can greatly facilitate the stable coexistence of strains. We demonstrate these dynamics using a model relevant to tuberculosis in which people may experience latent coinfection with both drug sensitive and drug resistant strains. Using this model, we show that the existence of a latent coinfected state allows the possibility that disease control interventions that target latency may facilitate the emergence of drug resistance.
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Affiliation(s)
- Caroline Colijn
- Department of Engineering Mathematics, University of Bristol, Bristol, UK.
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127
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Temple B, Ayakaka I, Ogwang S, Nabanjja H, Kayes S, Nakubulwa S, Worodria W, Levin J, Joloba M, Okwera A, Eisenach KD, McNerney R, Elliott AM, Smith PG, Mugerwa RD, Ellner JJ, Jones-López EC. Rate and amplification of drug resistance among previously-treated patients with tuberculosis in Kampala, Uganda. Clin Infect Dis 2008; 47:1126-34. [PMID: 18808360 PMCID: PMC2883442 DOI: 10.1086/592252] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Drug-resistant Mycobacterium tuberculosis has emerged as a global threat. In resource-constrained settings, patients with a history of tuberculosis (TB) treatment may have drug-resistant disease and may experience poor outcomes. There is a need to measure the extent of and risk factors for drug resistance in such patients. METHODS From July 2003 through November 2006, we enrolled 410 previously treated patients with TB in Kampala, Uganda. We measured the prevalence of resistance to first- and second-line drugs and analyzed risk factors associated with baseline and acquired drug resistance. RESULTS The prevalence of multidrug-resistant TB was 12.7% (95% confidence interval [95% CI], 9.6%-16.3%). Resistance to second-line drugs was low. Factors associated with multidrug-resistant TB at enrollment included a history of treatment failure (odds ratio, 23.6; 95% CI, 7.7-72.4), multiple previous TB episodes (odds ratio, 15.6; 95% CI, 5.0-49.1), and cavities present on chest radiograph (odds ratio, 5.9; 95% CI, 1.2-29.5). Among a cohort of 250 patients, 5.2% (95% CI, 2.8%-8.7%) were infected with M. tuberculosis that developed additional drug resistance. Amplification of drug resistance was associated with existing drug resistance at baseline (P < .01) and delayed sputum culture conversion (P < .01). CONCLUSIONS The burden of drug resistance in previously treated patients with TB in Uganda is sizeable, and the risk of generating additional drug resistance is significant. There is an urgent need to improve the treatment for such patients in low-income countries.
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Affiliation(s)
- Beth Temple
- Medical Research Council-Uganda Virus Research Institute, Uganda Research Unit on AIDS, Entebbe, Uganda
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128
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Nunn AJ, Phillips PP, Gillespie SH. Design issues in pivotal drug trials for drug sensitive tuberculosis (TB). Tuberculosis (Edinb) 2008; 88 Suppl 1:S85-92. [DOI: 10.1016/s1472-9792(08)70039-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Are survey-based estimates of the burden of drug resistant TB too low? Insight from a simulation study. PLoS One 2008; 3:e2363. [PMID: 18523659 PMCID: PMC2408555 DOI: 10.1371/journal.pone.0002363] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 04/28/2008] [Indexed: 11/25/2022] Open
Abstract
Background The emergence of tuberculosis resistant to multiple first- and second-line antibiotics poses challenges to a global control strategy that relies on standard drug treatment regimens. Highly drug-resistant strains of Mycobacterium tuberculosis have been implicated in outbreaks and have been found throughout the world; a comprehensive understanding the magnitude of this threat requires an accurate assessment of the worldwide burden of resistance. Unfortunately, in many settings where resistance is emerging, laboratory capacity is limited and estimates of the burden of resistance are obtained by performing drug sensitivity testing on a sample of incident cases rather than through the use of routine surveillance. Methodology/Principal Findings Using an individual-based dynamic tuberculosis model to simulate surveillance strategies for drug resistance, we found that current surveys may underestimate the total burden of resistant tuberculosis because cases of acquired resistance are undercounted and resistance among prevalent cases is not assessed. We explored how this bias is affected by the maturity of the epidemic and by the introduction of interventions that target the emergence and spread of resistant tuberculosis. Conclusions Estimates of drug resistant tuberculosis based on samples of incident cases should be viewed as a lower bound of the total burden of resistance.
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130
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Abstract
Multidrug-resistant tuberculosis (MDR-TB) with bacillary resistance to at least isoniazid and rifampicin in vitro is a worldwide phenomenon. Hot spots of the disease are found scattered in different continents. Prevention of its development through good tuberculosis control programmes operating under the directly observed therapy, short-course (DOTS) strategy is of paramount importance. However, with established MDR-TB, treatment with alternative and specific chemotherapy is necessary to achieve a beneficial outcome. Such an approach on a programme basis is currently known as the 'DOTS-Plus' strategy. Second-line (reserve) drugs utilized in the treatment of MDR-TB are generally less potent and more toxic, perhaps with the notable exceptions of some fluoroquinolones and injectable agents. Surgery has a distinct adjunctive role for the management of MDR-TB in selected patients. The emergence of extensively drug-resistant tuberculosis (XDR-TB), that is, MDR-TB with additional bacillary resistance to the fluoroquinolones and injectables, has provided a very alarming challenge to global health, as the disease currently has a low cure rate and high mortality. In order to combat XDR-TB, strengthening of DOTS and DOTS-Plus programmes is mandatory, especially in the face of surging HIV infection. Furthermore, more attention needs to be focused on developing new drugs with potent bactericidal and sterilizing activities and low side-effects, and above all, drugs that are affordable for communities worldwide.
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Affiliation(s)
- Wing Wai Yew
- Tuberculosis and Chest Unit, Grantham Hospital, Hong Kong, China.
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131
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Blaas SH, Mütterlein R, Weig J, Neher A, Salzberger B, Lehn N, Naumann L. Extensively drug resistant tuberculosis in a high income country: a report of four unrelated cases. BMC Infect Dis 2008; 8:60. [PMID: 18454863 PMCID: PMC2413242 DOI: 10.1186/1471-2334-8-60] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 05/02/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Multi drug resistance of Mycobacterium tuberculosis (M. tuberculosis) remains a major threat to public health, reinforced by recent reports about the clinical course of patients infected with extensively drug resistant (XDR) strains in South Africa. There is little information about the clinical course of XDR tuberculosis patients in industrialised countries. METHODS We evaluated all isolates of M. tuberculosis, in which drug susceptibility testing was performed at our institution since 1997, for multi and extensive drug resistance. Clinical courses of patients infected by strains fulfilling the recently revised criteria for XDR tuberculosis were analysed. RESULTS Four XDR M. tuberculosis isolates were identified. All patients had immigrated to Germany from Russia, Georgia, and former Yugoslavia and none were infected by the human immunodeficiency virus. All patients where treated for tuberculosis for 5.5 to 15 years and for XDR tuberculosis for 1.9 to 2.5 years. They received inhospital treatment in Germany for 11 months, 4.5 years and twice for 6 years. Non-compliance was an important factor in all four patients, three patients had to be treated in Germanys only locked facility for tuberculosis treatment. One patient with XDR tuberculosis died, one patient had still open pulmonary tuberculosis at last contact and 2 patients were cured. CONCLUSION Cases of XDR tuberculosis have been treated in our region for several years. Even in a high income setting, XDR tuberculosis has a tremendous impact on quality of live, outcome and the total cost. All reasonable efforts to prevent the spread of XDR tuberculosis must be made and maintained.
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Affiliation(s)
- Stefan H Blaas
- Department of Internal Medicine I, Regensburg University, Regensburg, Germany.
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132
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Fang R, Li X, Li J, Wu J, Shen X, Gui X, DeRiemer K, Liu L, Mei J, Gao Q. Mixed infections of Mycobacterium tuberculosis in tuberculosis patients in Shanghai, China. Tuberculosis (Edinb) 2008; 88:469-73. [PMID: 18424179 DOI: 10.1016/j.tube.2008.02.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 01/22/2008] [Accepted: 02/16/2008] [Indexed: 10/22/2022]
Abstract
We applied a 7 loci Variable-Number-Tandem-Repeats (VNTR-7) analysis method to identify mixed infections of Mycobacterium tuberculosis and to estimate the rate of mixed infections among pulmonary tuberculosis patients in Shanghai, China. We validated the VNTR-7 method and used it to genotype an isolate from each of the 249 from pulmonary tuberculosis patients reported from the Songjiang and Chongming districts in Shanghai during 2006. We identified 14 patients with mixed infections, and the estimated rate of mixed infections was 5.6% (14/249) (95% CI 3.1%-9.2%). Mixed infections were observed more frequently among tuberculosis patients undergoing retreatment (15.6%) than among new cases (4.1%) (p<0.05), and among tuberculosis patients whose disease was caused by non-Beijing genotype strains (12.5%) versus Beijing genotype strains (3.5%) (p<0.05). The VNTR-7 method is a highly sensitive, practical tool with relatively high discriminatory power, making it useful for studying mixed infections.
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Affiliation(s)
- Rendong Fang
- Shanghai Institutes of Preventive Medicine, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, China
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133
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The challenge of re-treatment pulmonary tuberculosis at two teaching and referral hospitals in Uganda. Afr Health Sci 2007; 7:136-42. [PMID: 18052866 DOI: 10.5555/afhs.2007.7.3.136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022] Open
Abstract
BACKGROUND With an annual tuberculosis (TB) incidence of about 350 cases per 100,000 of the population, Uganda is a high burden country. Moreover, it is evident that some TB patients have been treated for a previous episode of the disease. OBJECTIVE To highlight the burden of re-treatment pulmonary TB and examine patient factors associated with re-treatment among adults at two teaching and referral hospitals, Mbarara and Mulago. METHODS A descriptive cross sectional study with data collection between September 2004 and March 2005; we calculated the prevalence and used logistic regression to explore factors associated with re-treatment. RESULTS The prevalence of re-treatment pulmonary TB at Mbarara based on medical records was 30.0% (95%CI: 21.2 to 40.0), and 21.3% (95%CI: 12.9 to 31.8) from exit interviews. The corresponding estimates at Mulago hospital were 12.0% (95% CI: 6.4 to 20.0) and 43.9% (33.0 to 55.3). Compared to the 18-26 year age category, the prevalence odds ratio (POR) for a seven-year increase in age was 1.54 (95%CI: 1.04-2.28; p = 0.027), while female patients were 0.39 (95%CI: 0.17-0.90; p = 0.025) times less likely to report re-treatment disease than males, in this facility-based study. CONCLUSIONS Re-treatment pulmonary TB is frequent at the two teaching and referral hospitals. A contribution to re-treatment prevention should entail more rigorous management of new TB cases, particularly at lower levels of care.
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134
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Basu S, Andrews JR, Poolman EM, Gandhi NR, Shah NS, Moll A, Moodley P, Galvani AP, Friedland GH. Prevention of nosocomial transmission of extensively drug-resistant tuberculosis in rural South African district hospitals: an epidemiological modelling study. Lancet 2007; 370:1500-7. [PMID: 17964351 PMCID: PMC3711808 DOI: 10.1016/s0140-6736(07)61636-5] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Extensively drug-resistant (XDR) tuberculosis has spread among hospitalised patients in South Africa, but the epidemic-level effect of hospital-based infection control strategies remains unknown. We modelled the plausible effect of rapidly available infection control strategies on the overall course of the XDR tuberculosis epidemic in a rural area of South Africa. METHODS We investigated the effect of administrative, environmental, and personal infection control measures on the epidemic trajectory of XDR tuberculosis in the rural community of Tugela Ferry. Assessments were done with a mathematical model incorporating over 2 years of longitudinal inpatient and community-based data. The model simulated inpatient airborne tuberculosis transmission, community tuberculosis transmission, and the effect of HIV and antiretroviral therapy. FINDINGS If no new interventions are introduced, about 1300 cases of XDR tuberculosis are predicted to occur in the area of Tugela Ferry by the end of 2012, more than half of which are likely to be nosocomially transmitted. Mask use alone would avert fewer than 10% of cases in the overall epidemic, but could prevent a large proportion of cases of XDR tuberculosis in hospital staff. The combination of mask use with reduced hospitalisation time and a shift to outpatient therapy could prevent nearly a third of XDR tuberculosis cases. Supplementing this approach with improved ventilation, rapid drug resistance testing, HIV treatment, and tuberculosis isolation facilities could avert 48% of XDR tuberculosis cases (range 34-50%) by the end of 2012. However, involuntary detention could result in an unexpected rise in incidence due to restricted isolation capacity. INTERPRETATION A synergistic combination of available nosocomial infection control strategies could prevent nearly half of XDR tuberculosis cases, even in a resource-limited setting. XDR tuberculosis transmission will probably continue in the community, indicating the need to develop and implement parallel community-based programmes.
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Affiliation(s)
- Sanjay Basu
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA.
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135
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Gelmanova IY, Keshavjee S, Golubchikova VT, Berezina VI, Strelis AK, Yanova GV, Atwood S, Murray M. Barriers to successful tuberculosis treatment in Tomsk, Russian Federation: non-adherence, default and the acquisition of multidrug resistance. Bull World Health Organ 2007; 85:703-11. [PMID: 18026627 PMCID: PMC2636414 DOI: 10.2471/blt.06.038331] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 03/09/2007] [Accepted: 03/12/2007] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To identify barriers to successful tuberculosis (TB) treatment in Tomsk, Siberia, by analysing individual and programmatic risk factors for non-adherence, default and the acquisition of multidrug resistance in a TB treatment cohort in the Russian Federation. METHODS We conducted a retrospective cohort study of consecutively enrolled, newly detected, smear and/or culture-positive adult TB patients initiating therapy in a DOTS programme in Tomsk between 1 January and 31 December 2001. FINDINGS Substance abuse was strongly associated with non-adherence [adjusted odds ratio (OR): 7.3; 95% confidence interval (CI): 2.89-18.46] and with default (adjusted OR: 11.2; 95% CI: 2.55-49.17). Although non-adherence was associated with poor treatment outcomes (OR: 2.4; 95% CI: 1.1-5.5), it was not associated with the acquisition of multi-drug resistance during the course of therapy. Patients who began treatment in the hospital setting or who were hospitalized later during their treatment course had a substantially higher risk of developing multidrug-resistant TB than those who were treated as outpatients (adjusted HRs: 6.34; 95% CI: 1.35-29.72 and 6.26; 95% CI: 1.02-38.35 respectively). CONCLUSION In this cohort of Russian TB patients, substance abuse was a strong predictor of non-adherence and default. DOTS programmes may benefit from incorporating measures to diagnose and treat alcohol misuse within the medical management of patients undergoing TB therapy. Multidrug-resistant TB occurred among adherent patients who had been hospitalized in the course of their therapy. This raises the possibility that treatment for drug-sensitive disease unmasked a pre-existing population of drug-resistant organisms, or that these patients were reinfected with a drug-resistant strain of TB.
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Affiliation(s)
- I Y Gelmanova
- Partners In Health Russia, Moscow, Russian Federation
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136
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Bartu V. Multidrug-resistant tuberculosis in the Czech Republic: strategy and therapeutic outcomes. Eur J Clin Microbiol Infect Dis 2007; 26:603-5. [PMID: 17570000 DOI: 10.1007/s10096-007-0332-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- V Bartu
- Department of Respiratory Diseases, 1st Medical School, Charles University, Thomayer Faculty Hospital, Prague, Czech Republic.
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137
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Rodrigues P, Gomes MGM, Rebelo C. Drug resistance in tuberculosis—a reinfection model. Theor Popul Biol 2007; 71:196-212. [PMID: 17174368 DOI: 10.1016/j.tpb.2006.10.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 08/30/2006] [Accepted: 10/17/2006] [Indexed: 10/24/2022]
Abstract
There is increasing recognition that reinfection is an important component of TB transmission. Moreover, it has been shown that partial immunity has significant epidemiological consequences, particularly in what concerns disease prevalence and effectiveness of control measures. We address the problem of drug resistance as a competition between two types of strains of Mycobacterium tuberculosis: those that are sensitive to anti-tuberculosis drugs and those that are resistant. Our objective is to characterise the role of reinfection in the transmission of drug-resistant tuberculosis. The long-term behaviour of our model reflects how reinfection modifies the conditions for coexistence of sensitive and resistant strains. This sets the scene for discussing how strain prevalence is affected by different control strategies. It is shown that intervention effectiveness is highly sensitive to the baseline epidemiological setting.
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Affiliation(s)
- Paula Rodrigues
- Instituto Gulbenkian de Ciência, Apartado 14, 2781-901 Oeiras, Portugal.
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138
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Abebe F, Bjune G. The emergence of Beijing family genotypes of Mycobacterium tuberculosis and low-level protection by bacille Calmette-Guérin (BCG) vaccines: is there a link? Clin Exp Immunol 2006; 145:389-97. [PMID: 16907905 PMCID: PMC1809707 DOI: 10.1111/j.1365-2249.2006.03162.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The world is confronted with major tuberculosis (TB) outbreaks at a time when the protection of bacillus Calmette-Guérin (BCG) vaccine has become inconsistent and controversial. Major TB outbreaks are caused by a group of genetically similar strains of Mycobacterium tuberculosis (Mtb) strains, including the Beijing family genotypes. The Beijing family genotypes exhibit important pathogenic features such high virulence, multi-drug resistance and exogenous reinfection. These family strains have developed mechanisms that modulate/suppress immune responses by the host, such as inhibition of apoptosis of infected macrophages, diminished production of interleukin (IL)-2, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and elevated levels of IL-10 and IL-18. They demonstrate distinct expression of proteins, such as several species of alpha-crystallin (a known Mtb virulence factor), but decreased expression of some antigens such as heat shock protein of 65 kDa, phosphate transport subunit S and a 47-kDa protein. In addition, the Beijing family strains specifically produce a highly bioactive lipid (a polyketide synthase)-derived phenolic glycolipid. This altered expression of proteins/glycolipids may be important factors underlying the success of the Beijing family strains. The Beijing family strains are speculated to have originated from South-east Asia, where BCG vaccination has been used for more than 60 years. The hypothesis that mass BCG vaccination may have been a selective factor that favoured genotypic and phenotypic characteristic acquired by the Beijing family strains is discussed.
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Affiliation(s)
- F Abebe
- University of Oslo, International Community Health, Oslo, Norway.
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139
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Mathema B, Kurepina NE, Bifani PJ, Kreiswirth BN. Molecular epidemiology of tuberculosis: current insights. Clin Microbiol Rev 2006; 19:658-85. [PMID: 17041139 PMCID: PMC1592690 DOI: 10.1128/cmr.00061-05] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular epidemiologic studies of tuberculosis (TB) have focused largely on utilizing molecular techniques to address short- and long-term epidemiologic questions, such as in outbreak investigations and in assessing the global dissemination of strains, respectively. This is done primarily by examining the extent of genetic diversity of clinical strains of Mycobacterium tuberculosis. When molecular methods are used in conjunction with classical epidemiology, their utility for TB control has been realized. For instance, molecular epidemiologic studies have added much-needed accuracy and precision in describing transmission dynamics, and they have facilitated investigation of previously unresolved issues, such as estimates of recent-versus-reactive disease and the extent of exogenous reinfection. In addition, there is mounting evidence to suggest that specific strains of M. tuberculosis belonging to discrete phylogenetic clusters (lineages) may differ in virulence, pathogenesis, and epidemiologic characteristics, all of which may significantly impact TB control and vaccine development strategies. Here, we review the current methods, concepts, and applications of molecular approaches used to better understand the epidemiology of TB.
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Affiliation(s)
- Barun Mathema
- Tuberculosis Center, Public Health Research Institute, Newark, NJ 07103, USA.
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140
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Shamputa IC, Jugheli L, Sadradze N, Willery E, Portaels F, Supply P, Rigouts L. Mixed infection and clonal representativeness of a single sputum sample in tuberculosis patients from a penitentiary hospital in Georgia. Respir Res 2006; 7:99. [PMID: 16846493 PMCID: PMC1538999 DOI: 10.1186/1465-9921-7-99] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 07/17/2006] [Indexed: 11/23/2022] Open
Abstract
Background Studies on recurrent tuberculosis (TB), TB molecular epidemiology and drug susceptibility testing rely on the analysis of one Mycobacterium tuberculosis isolate from a single sputum sample collected at different disease episodes. This scheme rests on the postulate that a culture of one sputum sample is homogeneous and representative of the total bacillary population in a patient. Methods We systematically analysed several pre-treatment isolates from each of 199 smear-positive male adult inmates admitted to a prison TB hospital by standard IS6110 DNA fingerprinting, followed by PCR typing based on multiple loci containing variable number of tandem repeats (VNTRs) on a subset of isolates. Drug susceptibility testing (DST) was performed on all isolates for isoniazid, rifampicin, streptomycin and ethambutol. Results We found mixed infection in 26 (13.1%) cases. In contrast, analysis of a single pre-treatment isolate per patient would have led to missed mixed infections in all or 14 of these 26 cases by using only standard DNA fingerprinting or the PCR multilocus-based method, respectively. Differences in DST among isolates from the same patient were observed in 10 cases, of which 6 were from patients with mixed infection. Conclusion These results suggest that the actual heterogeneity of the bacillary population in patients, especially in high TB incidence settings, may be frequently underestimated using current analytical schemes. These findings have therefore important implications for correct interpretation and evaluation of molecular epidemiology data and in treatment evaluations.
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Affiliation(s)
- Isdore C Shamputa
- Prince Leopold Institute of Tropical Medicine, Mycobacteriology Unit, Nationalestraat 155, B-2000 Antwerp, Belgium
- Tropical Diseases Research Centre, Microbiology Unit, P. O. Box 71769, Ndola, Zambia
| | - Levan Jugheli
- Prince Leopold Institute of Tropical Medicine, Mycobacteriology Unit, Nationalestraat 155, B-2000 Antwerp, Belgium
- International Committee of the Red Cross, 4, Kedia Str. 380054, Tbilisi, Georgia
| | - Nikoloz Sadradze
- International Committee of the Red Cross, 4, Kedia Str. 380054, Tbilisi, Georgia
| | - Eve Willery
- Laboratoire des Mécanismes Moléculaires de la Pathogenèse Bactérienne, INSERM U629, Institut de Biologie/Institut Pasteur de Lille, Lille, France
| | - Françoise Portaels
- Prince Leopold Institute of Tropical Medicine, Mycobacteriology Unit, Nationalestraat 155, B-2000 Antwerp, Belgium
| | - Philip Supply
- Laboratoire des Mécanismes Moléculaires de la Pathogenèse Bactérienne, INSERM U629, Institut de Biologie/Institut Pasteur de Lille, Lille, France
| | - Leen Rigouts
- Prince Leopold Institute of Tropical Medicine, Mycobacteriology Unit, Nationalestraat 155, B-2000 Antwerp, Belgium
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141
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Cohen T, Lipsitch M, Walensky RP, Murray M. Beneficial and perverse effects of isoniazid preventive therapy for latent tuberculosis infection in HIV-tuberculosis coinfected populations. Proc Natl Acad Sci U S A 2006; 103:7042-7. [PMID: 16632605 PMCID: PMC1459015 DOI: 10.1073/pnas.0600349103] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Indexed: 11/18/2022] Open
Abstract
In sub-Saharan Africa, where the emergence of HIV has caused dramatic increases in tuberculosis (TB) case notifications, new strategies for TB control are necessary. Isoniazid preventive therapy (IPT) for HIV-TB coinfected individuals reduces the reactivation of latent Mycobacterium tuberculosis infections and is being evaluated as a potential community-wide strategy for improving TB control. We developed a mathematical model of TB/HIV coepidemics to examine the impact of community-wide implementation of IPT for TB-HIV coinfected individuals on the dynamics of drug-sensitive and -resistant TB epidemics. We found that community-wide IPT will reduce the incidence of TB in the short-term but may also speed the emergence of drug-resistant TB. We conclude that community-wide IPT in areas of emerging HIV and drug-resistant TB should be coupled with diagnostic and treatment policies designed to identify and effectively treat the increasing proportion of patients with drug-resistant TB.
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Affiliation(s)
- Ted Cohen
- Division of Social Medicine and Health Inequalities, Brigham and Women's Hospital, One Brigham Circle, 1620 Tremont Street, Boston, MA 02120, USA.
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142
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Affiliation(s)
- Wing Wai Yew
- Grantham Hospital Tuberculosis and Chest Unit, 125 Wong Chuk Hang Road, Hong Kong, China.
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143
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Behr MA. Polyclonal tuberculosis and the emergence of drug resistance. Am J Respir Crit Care Med 2005; 172:521-2. [PMID: 16120715 DOI: 10.1164/rccm.2506008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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