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1.
Trop Med Int Health ; 2022 Aug 17.
Article in English | MEDLINE | ID: mdl-36089572

ABSTRACT

OBJECTIVE: To determine the levels and patterns of resistance to first- and second-line anti-tuberculosis (TB) drugs among new and previously treated sputum smear positive pulmonary TB (PTB) patients. METHODS: We conducted a nationally representative cross-sectional facility-based survey in June 2017-July 2018 involving 45 clusters selected based on probability proportional to size. The survey aimed to determine the prevalence of anti-TB drug resistance and associated risk factors among smear positive PTB patients in Tanzania. Sputum samples were examined using smear microscopy, Xpert MTB/RIF, culture and drug susceptibility testing (DST). Logistic regression was used to account for missing data and sampling design effects on the estimates and their standard errors. RESULTS: We enrolled 1557 TB patients, including 1408 (90.4%) newly diagnosed and 149 (9.6%) previously treated patients. The prevalence of multidrug-resistant TB (MDR-TB) was 0.85% [95% confidence interval (CI): 0.4-1.3] among new cases and 4.6% (95% CI: 1.1-8.2) among previously treated cases. The prevalence of Mycobacterium tuberculosis strains resistant to any of the four first-line anti-TB drugs (isoniazid, rifampicin, streptomycin and ethambutol) was 1.7% among new TB patients and 6.5% among those previously treated. Drug resistance to all first-line drugs was similar (0.1%) in new and previously treated patients. None of the isolates displayed poly-resistance or extensively drug-resistant TB (XDR-TB). The only risk factor for MDR-TB was history of previous TB treatment (odds ratio = 5.7, 95% CI: 1.9-17.2). CONCLUSION: The burden of MDR-TB in the country was relatively low with no evidence of XDR-TB. Given the overall small number of MDR-TB cases in this survey, it will be beneficial focusing efforts on intensified case detection including universal DST.

2.
Respirol Case Rep ; 10(9): e01020, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36034178

ABSTRACT

Cystic pulmonary tuberculosis is a unique form of pulmonary tuberculosis (PTB) presenting with multiple reversible cysts of the lung. Unlike the other forms, this cystic lung disease can improve with prompt tuberculosis treatments. Here we report the case of a 15-year-old girl who presented with respiratory failure and severe lung damage at hospital admission. We diagnosed her with PTB based on her positive GeneXpert result test. The patient was treated with a standard tuberculosis regimen for 6 months and recovered completely.

3.
BMC Genomics ; 23(1): 561, 2022 Aug 05.
Article in English | MEDLINE | ID: mdl-35931954

ABSTRACT

BACKGROUND: Mycobacterium tuberculosis presents several lineages each with distinct characteristics of evolutionary status, transmissibility, drug resistance, host interaction, latency, and vaccine efficacy. Whole genome sequencing (WGS) has emerged as a new diagnostic tool to reliably inform the occurrence of phylogenetic lineages of Mycobacterium tuberculosis and examine their relationship with patient demographic characteristics and multidrug-resistance development. METHODS: 191 Mycobacterium tuberculosis isolates obtained from a 2017/2018 Tanzanian drug resistance survey were sequenced on the Illumina Miseq platform at Supranational Tuberculosis Reference Laboratory in Uganda. Obtained fast-q files were imported into tools for resistance profiling and lineage inference (Kvarq v0.12.2, Mykrobe v0.8.1 and TBprofiler v3.0.5). Additionally for phylogenetic tree construction, RaxML-NG v1.0.3(25) was used to generate a maximum likelihood phylogeny with 800 bootstrap replicates. The resulting trees were plotted, annotated and visualized using ggtree v2.0.4 RESULTS: Most [172(90.0%)] of the isolates were from newly treated Pulmonary TB patients. Coinfection with HIV was observed in 33(17.3%) TB patients. Of the 191 isolates, 22(11.5%) were resistant to one or more commonly used first line anti-TB drugs (FLD), 9(4.7%) isolates were MDR-TB while 3(1.6%) were resistant to all the drugs. Of the 24 isolates with any resistance conferring mutations, 13(54.2%) and 10(41.6%) had mutations in genes associated with resistance to INH and RIF respectively. The findings also show four major lineages i.e. Lineage 3[81 (42.4%)], followed by Lineage 4 [74 (38.7%)], the Lineage 1 [23 (12.0%)] and Lineages 2 [13 (6.8%)] circulaing in Tanzania. CONCLUSION: The findings in this study show that Lineage 3 is the most prevalent lineage in Tanzania whereas drug resistant mutations were more frequent among isolates that belonged to Lineage 4.


Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Multidrug-Resistant , Tuberculosis , Antitubercular Agents/pharmacology , Antitubercular Agents/therapeutic use , Demography , Drug Resistance, Multiple, Bacterial/genetics , Genotype , Humans , Microbial Sensitivity Tests , Mutation , Phylogeny , Tanzania/epidemiology , Tuberculosis/microbiology , Tuberculosis, Multidrug-Resistant/drug therapy
4.
JAC Antimicrob Resist ; 4(2): dlac042, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35465240

ABSTRACT

Background: Rifampicin- or multidrug-resistant (RR/MDR) Mycobacterium tuberculosis complex (MTBC) strains account for considerable morbidity and mortality globally. WGS-based prediction of drug resistance may guide clinical decisions, especially for the design of RR/MDR-TB therapies. Methods: We compared WGS-based drug resistance-predictive mutations for 42 MTBC isolates from MDR-TB patients in Tanzania with the MICs of 14 antibiotics measured in the Sensititre™ MycoTB assay. An isolate was phenotypically categorized as resistant if it had an MIC above the epidemiological-cut-off (ECOFF) value, or as susceptible if it had an MIC below or equal to the ECOFF. Results: Overall, genotypically non-wild-type MTBC isolates with high-level resistance mutations (gNWT-R) correlated with isolates with MIC values above the ECOFF. For instance, the median MIC value (mg/L) for rifampicin-gNWT-R strains was >4.0 (IQR 4.0-4.0) compared with 0.5 (IQR 0.38-0.50) in genotypically wild-type (gWT-S, P < 0.001); isoniazid-gNWT-R >4.0 (IQR 2.0-4.0) compared with 0.25 (IQR 0.12-1.00) among gWT-S (P = 0.001); ethionamide-gNWT-R 15.0 (IQR 10.0-20.0) compared with 2.50 (IQR; 2.50-5.00) among gWT-S (P < 0.001). WGS correctly predicted resistance in 95% (36/38) and 100% (38/38) of the rifampicin-resistant isolates with ECOFFs >0.5 and >0.125 mg/L, respectively. No known resistance-conferring mutations were present in genes associated with resistance to fluoroquinolones, aminoglycosides, capreomycin, bedaquiline, delamanid, linezolid, clofazimine, cycloserine, or p-amino salicylic acid. Conclusions: WGS-based drug resistance prediction worked well to rule-in phenotypic drug resistance and the absence of second-line drug resistance-mediating mutations has the potential to guide the design of RR/MDR-TB regimens in the future.

5.
BMC Infect Dis ; 21(1): 925, 2021 Sep 08.
Article in English | MEDLINE | ID: mdl-34493217

ABSTRACT

BACKGROUND: In the 2nd year of the COVID-19 pandemic, knowledge about the dynamics of the infection in the general population is still limited. Such information is essential for health planners, as many of those infected show no or only mild symptoms and thus, escape the surveillance system. We therefore aimed to describe the course of the pandemic in the Munich general population living in private households from April 2020 to January 2021. METHODS: The KoCo19 baseline study took place from April to June 2020 including 5313 participants (age 14 years and above). From November 2020 to January 2021, we could again measure SARS-CoV-2 antibody status in 4433 of the baseline participants (response 83%). Participants were offered a self-sampling kit to take a capillary blood sample (dry blood spot; DBS). Blood was analysed using the Elecsys® Anti-SARS-CoV-2 assay (Roche). Questionnaire information on socio-demographics and potential risk factors assessed at baseline was available for all participants. In addition, follow-up information on health-risk taking behaviour and number of personal contacts outside the household (N = 2768) as well as leisure time activities (N = 1263) were collected in summer 2020. RESULTS: Weighted and adjusted (for specificity and sensitivity) SARS-CoV-2 sero-prevalence at follow-up was 3.6% (95% CI 2.9-4.3%) as compared to 1.8% (95% CI 1.3-3.4%) at baseline. 91% of those tested positive at baseline were also antibody-positive at follow-up. While sero-prevalence increased from early November 2020 to January 2021, no indication of geospatial clustering across the city of Munich was found, although cases clustered within households. Taking baseline result and time to follow-up into account, men and participants in the age group 20-34 years were at the highest risk of sero-positivity. In the sensitivity analyses, differences in health-risk taking behaviour, number of personal contacts and leisure time activities partly explained these differences. CONCLUSION: The number of citizens in Munich with SARS-CoV-2 antibodies was still below 5% during the 2nd wave of the pandemic. Antibodies remained present in the majority of SARS-CoV-2 sero-positive baseline participants. Besides age and sex, potentially confounded by differences in behaviour, no major risk factors could be identified. Non-pharmaceutical public health measures are thus still important.


Subject(s)
COVID-19 , Pandemics , Follow-Up Studies , Germany/epidemiology , Humans , Infant, Newborn , Male , SARS-CoV-2
6.
Int J Environ Res Public Health ; 18(7)2021 03 30.
Article in English | MEDLINE | ID: mdl-33808249

ABSTRACT

Given the large number of mild or asymptomatic SARS-CoV-2 cases, only population-based studies can provide reliable estimates of the magnitude of the pandemic. We therefore aimed to assess the sero-prevalence of SARS-CoV-2 in the Munich general population after the first wave of the pandemic. For this purpose, we drew a representative sample of 2994 private households and invited household members 14 years and older to complete questionnaires and to provide blood samples. SARS-CoV-2 seropositivity was defined as Roche N pan-Ig ≥ 0.4218. We adjusted the prevalence for the sampling design, sensitivity, and specificity. We investigated risk factors for SARS-CoV-2 seropositivity and geospatial transmission patterns by generalized linear mixed models and permutation tests. Seropositivity for SARS-CoV-2-specific antibodies was 1.82% (95% confidence interval (CI) 1.28-2.37%) as compared to 0.46% PCR-positive cases officially registered in Munich. Loss of the sense of smell or taste was associated with seropositivity (odds ratio (OR) 47.4; 95% CI 7.2-307.0) and infections clustered within households. By this first population-based study on SARS-CoV-2 prevalence in a large German municipality not affected by a superspreading event, we could show that at least one in four cases in private households was reported and known to the health authorities. These results will help authorities to estimate the true burden of disease in the population and to take evidence-based decisions on public health measures.


Subject(s)
COVID-19 , Coronavirus Infections , Humans , Prevalence , Risk Factors , SARS-CoV-2
8.
Lancet Infect Dis ; 19(12): e444-e451, 2019 12.
Article in English | MEDLINE | ID: mdl-31451421

ABSTRACT

Antimicrobial resistance is one of the most important threats to global health security. A range of Gram-negative bacteria associated with high morbidity and mortality are now resistant to almost all available antibiotics. In this context of urgency to develop novel drugs, new antibiotics for multidrug-resistant Gram-negative bacteria (namely, ceftazidime-avibactam, plazomicin, and meropenem-vaborbactam) have been approved by regulatory authorities based on non-inferiority trials that provided no direct evidence of their efficacy against multidrug-resistant bacteria such as Enterobacteriaceae spp, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia, and Acinetobacter baumannii. The use of non-inferiority and superiority trials, and selection of appropriate and optimal study designs, remains a major challenge in the development, registration, and post-marketing implementation of new antibiotics. Using an example of the development process of ceftazidime-avibactam, we propose a strategy for a new research framework based on adaptive randomised clinical trials. The operational research strategy has the aim of assessing the efficacy of new antibiotics in special groups of patients, such as those infected with multidrug-resistant bacteria, who were not included in earlier phase studies, and for whom it is important to establish an appropriate standard of care.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/drug effects , Drug Resistance, Multiple, Bacterial , Humans , Microbial Sensitivity Tests , Product Surveillance, Postmarketing , Randomized Controlled Trials as Topic
10.
Lancet Infect Dis ; 15(6): 738-45, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25881871

ABSTRACT

The Ebola outbreak that has devastated parts of west Africa represents an unprecedented challenge for research and ethics. Estimates from the past three decades emphasise that the present effort to contain the epidemic in the three most affected countries (Guinea, Liberia, and Sierra Leone) has been insufficient, with more than 24,900 cases and about 10,300 deaths, as of March 25, 2015. Faced with such an exceptional event and the urgent response it demands, the use of randomised controlled trials (RCT) for Ebola-related research might be both unethical and infeasible and that potential interventions should be assessed in non-randomised studies on the basis of compassionate use. However, non-randomised studies might not yield valid conclusions, leading to large residual uncertainty about how to interpret the results, and can also waste scarce intervention-related resources, making them profoundly unethical. Scientifically sound and rigorous study designs, such as adaptive RCTs, could provide the best way to reduce the time needed to develop new interventions and to obtain valid results on their efficacy and safety while preserving the application of ethical precepts. We present an overview of clinical studies registered at present at the four main international trial registries and provide a simulation on how adaptive RCTs can behave in this context, when mortality varies simultaneously in either the control or the experimental group.


Subject(s)
Biomedical Research/ethics , Biomedical Research/methods , Disease Outbreaks , Hemorrhagic Fever, Ebola/epidemiology , Hemorrhagic Fever, Ebola/prevention & control , Africa, Western/epidemiology , Humans
11.
Lancet Infect Dis ; 13(6): 529-39, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23531391

ABSTRACT

Two decades ago, WHO declared tuberculosis a global emergency, and invested in the highly cost-effective directly observed treatment short-course programme to control the epidemic. At that time, most strains of Mycobacterium tuberculosis were susceptible to first-line tuberculosis drugs, and drug resistance was not a major issue. However, in 2013, tuberculosis remains a major public health concern worldwide, with prevalence of multidrug-resistant (MDR) tuberculosis rising. WHO estimates roughly 630 000 cases of MDR tuberculosis worldwide, with great variation in the frequency of MDR tuberculosis between countries. In the past 8 years, extensively drug-resistant (XDR) tuberculosis has emerged, and has been reported in 84 countries, heralding the possibility of virtually untreatable tuberculosis. Increased population movement, the continuing HIV pandemic, and the rise in MDR tuberculosis pose formidable challenges to the global control of tuberculosis. We provide an overview of the global burden of drug-resistant disease; discuss the social, health service, management, and control issues that fuel and sustain the epidemic; and suggest specific recommendations for important next steps. Visionary political leadership is needed to curb the rise of MDR and XDR tuberculosis worldwide, through sustained funding and the implementation of global and regional action plans.


Subject(s)
Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/isolation & purification , Tuberculosis, Multidrug-Resistant/drug therapy , Tuberculosis, Multidrug-Resistant/epidemiology , Antitubercular Agents/therapeutic use , Global Health , Humans , Prevalence , World Health Organization
12.
Lancet Infect Dis ; 13(5): 436-48, 2013 May.
Article in English | MEDLINE | ID: mdl-23531392

ABSTRACT

Recent data for the global burden of disease reflect major demographic and lifestyle changes, leading to a rise in non-communicable diseases. Most countries with high levels of tuberculosis face a large comorbidity burden from both non-communicable and communicable diseases. Traditional disease-specific approaches typically fail to recognise common features and potential synergies in integration of care, management, and control of non-communicable and communicable diseases. In resource-limited countries, the need to tackle a broader range of overlapping comorbid diseases is growing. Tuberculosis and HIV/AIDS persist as global emergencies. The lethal interaction between tuberculosis and HIV coinfection in adults, children, and pregnant women in sub-Saharan Africa exemplifies the need for well integrated approaches to disease management and control. Furthermore, links between diabetes mellitus, smoking, alcoholism, chronic lung diseases, cancer, immunosuppressive treatment, malnutrition, and tuberculosis are well recognised. Here, we focus on interactions, synergies, and challenges of integration of tuberculosis care with management strategies for non-communicable and communicable diseases without eroding the functionality of existing national programmes for tuberculosis. The need for sustained and increased funding for these initiatives is greater than ever and requires increased political and funder commitment.


Subject(s)
Communicable Disease Control/organization & administration , Tuberculosis/epidemiology , Acquired Immunodeficiency Syndrome/epidemiology , Acquired Immunodeficiency Syndrome/prevention & control , Coinfection/epidemiology , Communicable Disease Control/methods , Communicable Diseases/epidemiology , Comorbidity , Diabetes Mellitus/epidemiology , Global Health , Health Services Needs and Demand/organization & administration , Humans , Mycobacterium tuberculosis/pathogenicity , National Health Programs/economics , National Health Programs/organization & administration , Risk Factors , Socioeconomic Factors , Tuberculosis/microbiology , Tuberculosis/prevention & control
13.
J Infect Dis ; 205 Suppl 2: S147-58, 2012 May 15.
Article in English | MEDLINE | ID: mdl-22496353

ABSTRACT

Tuberculosis is unique among the major infectious diseases in that it lacks accurate rapid point-of-care diagnostic tests. Failure to control the spread of tuberculosis is largely due to our inability to detect and treat all infectious cases of pulmonary tuberculosis in a timely fashion, allowing continued Mycobacterium tuberculosis transmission within communities. Currently recommended gold-standard diagnostic tests for tuberculosis are laboratory based, and multiple investigations may be necessary over a period of weeks or months before a diagnosis is made. Several new diagnostic tests have recently become available for detecting active tuberculosis disease, screening for latent M. tuberculosis infection, and identifying drug-resistant strains of M. tuberculosis. However, progress toward a robust point-of-care test has been limited, and novel biomarker discovery remains challenging. In the absence of effective prevention strategies, high rates of early case detection and subsequent cure are required for global tuberculosis control. Early case detection is dependent on test accuracy, accessibility, cost, and complexity, but also depends on the political will and funder investment to deliver optimal, sustainable care to those worst affected by the tuberculosis and human immunodeficiency virus epidemics. This review highlights unanswered questions, challenges, recent advances, unresolved operational and technical issues, needs, and opportunities related to tuberculosis diagnostics.


Subject(s)
Tuberculosis/diagnosis , Antitubercular Agents/pharmacology , Antitubercular Agents/therapeutic use , Bacteriological Techniques/methods , Biomarkers , Drug Resistance, Bacterial , Humans , Tuberculosis/drug therapy
14.
J Infect Dis ; 205 Suppl 2: S228-40, 2012 May 15.
Article in English | MEDLINE | ID: mdl-22476720

ABSTRACT

Tuberculosis was declared a global emergency by the World Health Organization (WHO) in 1993. Following the declaration and the promotion in 1995 of directly observed treatment short course (DOTS), a cost-effective strategy to contain the tuberculosis epidemic, nearly 7 million lives have been saved compared with the pre-DOTS era, high cure rates have been achieved in most countries worldwide, and the global incidence of tuberculosis has been in a slow decline since the early 2000s. However, the emergence and spread of multidrug-resistant (MDR) tuberculosis, extensively drug-resistant (XDR) tuberculosis, and more recently, totally drug-resistant tuberculosis pose a threat to global tuberculosis control. Multidrug-resistant tuberculosis is a man-made problem. Laboratory facilities for drug susceptibility testing are inadequate in most tuberculosis-endemic countries, especially in Africa; thus diagnosis is missed, routine surveillance is not implemented, and the actual numbers of global drug-resistant tuberculosis cases have yet to be estimated. This exposes an ominous situation and reveals an urgent need for commitment by national programs to health system improvement because the response to MDR tuberculosis requires strong health services in general. Multidrug-resistant tuberculosis and XDR tuberculosis greatly complicate patient management within resource-poor national tuberculosis programs, reducing treatment efficacy and increasing the cost of treatment to the extent that it could bankrupt healthcare financing in tuberculosis-endemic areas. Why, despite nearly 20 years of WHO-promoted activity and >12 years of MDR tuberculosis-specific activity, has the country response to the drug-resistant tuberculosis epidemic been so ineffectual? The current dilemmas, unanswered questions, operational issues, challenges, and priority needs for global drug resistance screening and surveillance, improved treatment regimens, and management of outcomes and prevention of DR tuberculosis are discussed.


Subject(s)
Antitubercular Agents/pharmacology , Drug Resistance, Multiple, Bacterial , Global Health , Tuberculosis, Multidrug-Resistant/epidemiology , Tuberculosis, Multidrug-Resistant/prevention & control , Adult , Africa/epidemiology , Child , Communicable Disease Control/methods , Directly Observed Therapy/ethics , Drug Administration Schedule , Endemic Diseases , Health Policy , Humans , Mycobacterium tuberculosis/drug effects , Patient Rights , Time Factors , Tuberculosis, Multidrug-Resistant/diagnosis , Tuberculosis, Multidrug-Resistant/drug therapy
15.
J Infect Dis ; 205 Suppl 2: S250-7, 2012 May 15.
Article in English | MEDLINE | ID: mdl-22448027

ABSTRACT

A growing number of new drugs for the treatment of tuberculosis are in clinical development. Confirmatory phase 3 trials are expensive and time-consuming and the question of whether one particular drug combination can be used to treat tuberculosis is less important from a public health perspective than the question of which are the shortest, simplest, most effective, and safest regimens. While preclinical and phase 1 studies provide some guidance in the selection of combinations for clinical evaluation, a large number of combinations will require phase 2 testing to ensure that only the best regimens advance to phase 3. The multi-arm multi-stage trial design is an example of a treatment selection-adaptive design where multiple experimental arms are each simultaneously compared with a common control and interim analyses allow for poor performing arms to be dropped early. Such designs, if designed and implemented correctly, require fewer patients, can be completed in a shorter time frame, and answer more relevant questions without any loss in statistical validity or scientific integrity. There are, however, practical issues that must be considered in applying this in tuberculosis treatment trials. More innovative trials designs should be considered to speed drug and regimen development for the treatment of tuberculosis.


Subject(s)
Antitubercular Agents/therapeutic use , Clinical Trials as Topic/methods , Research Design , Tuberculosis/drug therapy , Antitubercular Agents/administration & dosage , Drug Therapy, Combination , Humans , Patient Selection , Reproducibility of Results , Time Factors
16.
Eur J Public Health ; 22(4): 598-601, 2012 Aug.
Article in English | MEDLINE | ID: mdl-21690183

ABSTRACT

BACKGROUND: Projects are the main financing mechanism within the EU community action programme for public health. This article reports the process of establishing and validating evaluation criteria for projects submitted for funding within this programme, to ensure that projects selected for funding conform with quality standards. METHODS: An evaluation checklist was developed, drawing on project management and health promotion literature, to Score 3 aspects of project quality: policy and contextual relevance (five criteria, scores 0-8), technical quality (five criteria, scored 0-6) and management quality (six criteria, scored 0-5). Teams of three people made consensus ratings with the checklist on each of 215 eligible applications submitted in response to Calls for Proposals in 2007 and 151 submitted in 2008. Construct validity, internal consistency and predictive validity were assessed on the grouped consensus ratings using psychometric test statistical methods. RESULTS: Principal component analyses on both the 2007 and 2008 data gave a three component solution, which largely coincides with the dimensions of contextual relevance, technical quality and management quality. Reliability analyses show high Cronbach α's (>0.86) for each of the three scales. Discriminant analyses indicate that all three of the dimensions contributed to the decision to fund a project. Over the 2 years, innovation, content specification, EU added value and geographical coverage contributing most consistently to the success of an application. CONCLUSION: The study shows the successful development and validation of criteria to evaluate EU health project grant proposals.


Subject(s)
Checklist/standards , Health Services Research/standards , Public Health , Quality Control , Research Support as Topic , European Union , Health Promotion/standards , Health Services Research/economics , Humans , Predictive Value of Tests , Principal Component Analysis , Program Development , Program Evaluation , Psychometrics , Reproducibility of Results , Research Support as Topic/economics
19.
Antimicrob Agents Chemother ; 46(5): 1204-11, 2002 May.
Article in English | MEDLINE | ID: mdl-11959546

ABSTRACT

To study the cost of chromosomal drug resistance mutations to bacteria, we investigated the fitness cost of mutations that confer resistance to different classes of antibiotics affecting bacterial protein synthesis (aminocyclitols, 2-deoxystreptamines, macrolides). We used a model system based on an in vitro competition assay with defined Mycobacterium smegmatis laboratory mutants; selected mutations were introduced by genetic techniques to address the possibility that compensatory mutations ameliorate the resistance cost. We found that the chromosomal drug resistance mutations studied often had only a small fitness cost; compensatory mutations were not involved in low-cost or no-cost resistance mutations. When drug resistance mutations found in clinical isolates were considered, selection of those mutations that have little or no fitness cost in the in vitro competition assay seems to occur. These results argue against expectations that link decreased levels of antibiotic consumption with the decline in the level of resistance.


Subject(s)
Chromosomes, Bacterial/genetics , Drug Resistance, Bacterial/genetics , Mutation , Mycobacterium smegmatis/drug effects , Mycobacterium smegmatis/growth & development , rRNA Operon/genetics , Anti-Bacterial Agents/pharmacology , Humans , Mycobacterium smegmatis/genetics , Ribosomal Proteins/genetics , Selection, Genetic , Streptomycin/pharmacology
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