Current Perspectives on Drug Susceptibility Testing of
            <i>Mycobacterium tuberculosis</i>
            Complex: the Automated Nonradiometric Systems

Piersimoni, Claudio; Olivieri, Armando; Benacchio, Luca; Scarparo, Claudio

doi:10.1128/jcm.44.1.20-28.2006

Cited by 107 publications

(83 citation statements)

References 29 publications

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“…All strains were initially tested by the NRCM for first-and second-line AST using known CCs for the B460 system (8,9,16,17) and three test concentrations for second-line AST in the M960 system. Second, the blinded panel of strains was tested by the other three collaborating laboratories using CCs as published for all antimicrobials in the B460 system and investigational CCs for all antimicrobials in the M960 system, except for p-aminosalicylic acid (PAS), moxifloxacin, and linezolid, which were tested against three antimicrobial concentrations due to the lack of published data.…”

Section: Methodsmentioning

confidence: 99%

Canadian Multicenter Laboratory Study for Standardized Second-Line Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis

et al. 2011

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The purpose of this study was to establish a standardized protocol for second-line antimicrobial susceptibility testing of Mycobacterium tuberculosis using the Bactec MGIT 960 system in Canadian laboratories. Four Canadian public health laboratories compared the susceptibility testing results of 9 second-line antimicrobials between the Bactec 460 and Bactec MGIT 960 systems. Based on the data generated, we have established that the Bactec MGIT 960 system provides results comparable to those obtained with the previous Bactec 460 method. The critical concentrations established for the testing of the antimicrobials used are as follows: amikacin, 1 g/ml; capreomycin, 2.5 g/ml; ethionamide, 5 g/ml; kanamycin, 2.5 g/ml; linezolid, 1 g/ml; moxifloxacin, 0.25 g/ml; ofloxacin, 2 g/ml; p-aminosalicylic acid, 4 g/ml; rifabutin, 0.5 g/ml.The Public Health Agency of Canada (PHAC) publishes yearly statistics on the antimicrobial resistance patterns of all laboratory-isolated Mycobacterium tuberculosis strains in Canada. From 2000 to 2010, the number of M. tuberculosis isolates resistant to one or more of the first-line antimicrobials has varied between 8.0% and 11.0% of all tuberculosis (TB) cases per year in Canada (15). Between 0.9% and 1.6% of these cases were considered multidrug resistant (MDR) TB. Since 2005, TB cases in the foreign-born Canadian population have accounted for more than 60% of all Canadian TB cases and greater than 90% of MDR TB cases (10-14).Currently it is recommended that after systematic testing against first-line anti-TB agents, isolates that are found to be monoresistant to rifampin or to demonstrate resistance to any two of the first-line antimicrobials be tested against a panel of secondline antimicrobials (3,7,21). Though the majority of resistant isolates in Canada show monoresistance to isoniazid (INH), recently published Clinical and Laboratory Standards Institute (CLSI) document M24-A2 recommends that second-line antimicrobial testing also be performed on isolates that are INH monoresistant in cases where fluoroquinolones may be added to the therapy. The current standard method for first-line antimicrobial sensitivity testing (AST) of M. tuberculosis in Canada is the Bactec MGIT 960 (M960) system (BD, Sparks, MD). Although the M960 system has been approved for first-line AST (2-4, 20), the Bactec 460 (B460; BD, Sparks, MD) and the agar proportion method are currently used for second-line AST since the M960 system had not been validated for this purpose (3,8). Due to the increasing demand for second-line AST and the discontinuation of the B460 technology by the manufacturer, a multicenter validation of a second-line AST panel for the M960 system was undertaken. A validated and standardized method and antimicrobial panel for second-line AST are required to ensure that antimicrobial-resistant cases of M. tuberculosis, including MDR and extensively drug-resistant cases, are identified in an accurate and timely manner and that susceptibility testing and reporting of these isolates are standardize...

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Section: Methodsmentioning

confidence: 99%

Canadian Multicenter Laboratory Study for Standardized Second-Line Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis

et al. 2011

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“…In this way, a molecular assay can reduce the delay of conventional liquid media-based systems. Genetic assays can identify EMB resistance with high inter-assay reproducibility by detecting mutations within the embB gene [14].…”

Section: Introductionmentioning

confidence: 99%

Frequency of mutational changes in the embB among the ethambutol-resistant strains of Mycobacterium tuberculosis in Iran

Rezaei

Haeili

Mohajeri

et al. 2016

J Infect Dev Ctries

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Introduction: Early detection of drug resistant tuberculosis is one of the main priorities of TB control program. Ethambutol (EMB) is a firstline anti-TB drug that is effective for preventing treatment failures caused by Mycobacterium tuberculosis strains that are resistant to other drugs. The aim of this study was to sequence the embB gene to characterize the mutations causing resistance to EMB and to analyze the relationship between bacterial genotype and EMB resistance among M. tuberculosis isolates in Iran. Methodology: A total of 20 M. tuberculosis isolates comprising 10 multidrug-resistant (MDR) and 10 non-MDR isolates, recovered from TB patients in four regions: Tehran, Isfahan, Zahedan, Khorasan, were analyzed. Mutational profiling was performed by amplifying and sequencing the embB gene. Spoligotyping was carried out to characterize the bacterial genotype. Results: Phenotypic EMB resistance was found in 13 strains. Mutations affecting ethambutol resistance-determining region (ERDR) of the embB were identified in 6 of 13 EMB-resistant isolates. The majority of these mutations resulted in amino acid substitution at position 306 (M306V). A novel mutation at codon 366 was identified (S366L) in one isolate. Ural was the most predominant genotype in the studied population. Beijing genotype was associated with both MDR and EMB resistance in which all mutations occurred at codon 306 of the embB gene. Conclusion: A significant association between Beijing genotype and EMB resistance was found, mainly due to mutations at embB306. Results of this study can be used as a basis to develop or improve rapid molecular tests to monitor drug-resistant strains in this country.

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“…Automated liquid culture systems have significantly shortened turnaround times for drug susceptibility tests (DSTs) compared to solid media, but bacteriological assays are technically demanding and still require approximately 7 to 10 days (34). Detection of genetic mutations that correlate with resistance to certain antimicrobial agents represents a more rapid alternative.…”

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confidence: 99%

Evaluation of Two Molecular Assays for Rapid Detection of Mycobacterium tuberculosis Resistance to Fluoroquinolones in High-Tuberculosis and -Multidrug-Resistance Settings

et al. 2011

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The Russian Federation is a high-tuberculosis (TB)-burden country with high rates of drug resistance, including multidrug and extensive drug resistance to TB (M/XDRTB). Rapid diagnosis of resistance to fluoroquinolones (FQs) using molecular assays is essential for the implementation of appropriate drug regimens and prevention of the transmission of XDR strains. A total of 51 individual MDRTB strains were tested by pyrosequencing of the quinolone resistance determining region of the gyrA gene and the GenoType MTBDRsl assay (Hain Lifescience, GmbH, Nehren, Germany), and the results were evaluated against those obtained by phenotypic drug susceptibility testing (DST). Mutations were detected in 25 (78.1%) FQ-resistant strains, with the majority of mutations (n ‫؍‬ 19 [73.0%]) found in codon 94 of the gyrA gene; the novel mutation 1457 C3⌻ was found in the gyrB gene. Three mixed allelic variants were detected, which is a well-known phenomenon in areas with high TB and drug-resistant TB rates. The sensitivity and specificity of pyrosequencing (86.2 and 100%, respectively) and MTBDRsl (86.2 and 100%, respectively) were high; however, the results for 5.9% of the analyzed strains were unreadable when MTBDRsl was used. The MTBDRsl and pyrosequencing assays offer a rapid and accurate means for diagnosing resistance to FQs in high-TB-burden areas.Tuberculosis (TB) remains a major threat to public health worldwide and in the developing world in particular, causing almost 2 million deaths annually. The real magnitude of drug resistance is not yet known, although the Indian subcontinent, China, and Russia are believed to account for the majority of cases globally (48).Multidrug-resistant TB (MDRTB), caused by TB bacilli resistant to both isoniazid (INH) and rifampin (RIF), poses difficulties in diagnosis and treatment, with lower survival rates (especially in HIV-infected persons) and the associated high costs of TB control programs. The World Health Organization (WHO) estimates current MDRTB rates in new and previously treated cases globally to be 2.9 and 15.3%, respectively (50).The Russian Federation is a high-TB-burden country with high rates of TB drug resistance, dominated by TB strains of the Beijing family reported to be associated with MDRTB (7, 42). The Samara Oblast (Central Russia) is a hot spot for both TB and HIV epidemics; ca. 20% of new TB cases are MDR, with rates even higher in previously treated cases and in the prison sector (8). Converging TB, drug-resistant TB, and HIV epidemics pose a serious problem for low-and middle-income countries such as Russia where access to second-and third-line drug therapy is limited (2, 8).The rate of extensively drug-resistant TB (XDRTB) (which is caused by MDRTB bacilli with additional resistance to a fluoroquinolone [FQ] and one or more injectable drugs) has been increasing in Russia (36) due to multiple incomplete treatment regimens and poor infection control practice. Cases of XDRTB show a high rate of treatment failure and mortality especially in XDRTB patients with c...

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Current Perspectives on Drug Susceptibility Testing of Mycobacterium tuberculosis Complex: the Automated Nonradiometric Systems

Cited by 107 publications

References 29 publications

Canadian Multicenter Laboratory Study for Standardized Second-Line Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis

Canadian Multicenter Laboratory Study for Standardized Second-Line Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis

Frequency of mutational changes in the embB among the ethambutol-resistant strains of Mycobacterium tuberculosis in Iran

Evaluation of Two Molecular Assays for Rapid Detection of Mycobacterium tuberculosis Resistance to Fluoroquinolones in High-Tuberculosis and -Multidrug-Resistance Settings

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