Laboratory Diagnosis of Mycobacterial Infections: New Tools and Lessons Learned

Even in the 21st century, tuberculosis continues to be a problem. Although the number of cases continues gradually to decrease in the United States, cases get more difficult to treat, specifically those that are multiple-drug resistant. Infection of one-third of the world's population ensures that tuberculosis will not disappear in the near future. In light of this, it will be useful to know the goals for the health care system and how these goals may be accomplished. Laboratory testing in the mycobacteriology field is experiencing more changes today than ever before. Determining what assays will be most useful to the clinician is a challenge, and acceptance of the new technology by the medical community an even greater one. Clinicians must use the best available resources to determine the most appropriate care for their patients and work together with the laboratory to ensure that the communication channels are open. This review focuses on current state-of-the-art resources useful for accurate and rapid laboratory diagnosis of mycobacterial infection

A multilaboratory, multicountry study to determine bedaquiline MIC quality control ranges for phenotypic drug susceptibility testing

The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated. Mycobacterium tuberculosis H37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37Rv M. tuberculosis reference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide.All participating laboratories received funds for this study from Janssen Pharmaceuticals except the Reference Laboratory, Division of TB Elimination, United States Centers for Disease Control and Prevention, Atlanta, GA, USA. Support for medical writing assistance was provided by Janssen Pharmaceuticals.http://jcm.asm.orghj2017Medical Microbiolog

A multilaboratory, multicountry study to determine MIC quality control ranges for phenotypic drug susceptibility testing of selected first-line antituberculosis dugs, second-line injectables, fluoroquinolones, clofazimine, and linezolid

OBJECTIVES : Our objective was to establish reference minimal inhibitory concentration (MIC) quality control (QC) ranges for drug susceptibility testing of antimycobacterials, including firstline agents, second-line injectables, fluoroquinolones and World Health Organization Category 5 drugs for multidrug-resistant tuberculosis, using a 7H9 broth microdilution MIC method. METHODS : A Tier-2 reproducibility study was conducted in eight participating laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Three lots of custom-made frozen 96-well polystyrene micro titer plates were used and pre-prepared with 2X pre-diluted drugs in 7H9 broth/oleic acid albumin dextrose catalase. The QC reference strain was Mycobacterium tuberculosis (MTB) H37Rv. MIC frequency, mode and geometric mean were calculated for each drug. QC ranges were derived, based on predefined, strict CLSI criteria. Any data lying outside CLSI criteria resulted in exclusion of the entire laboratory dataset. RESULTS : Data from one laboratory were excluded due to higher MIC values than for other laboratories. QC ranges were established for eleven drugs: isoniazid (0.03–0.12 μg/ml), rifampin (0.03–0.25 μg/ml), ethambutol (0.25–2 μg/ml), levofloxacin (0.12–1 μg/ml), moxifloxacin (0.06–0.5 μg/ml), ofloxacin (0.25–2 μg/ml), amikacin (0.25–2 μg/ml), kanamycin (0.25–2 μg/ml), capreomycin (0.5–4 μg/ml), linezolid (0.25–2 μg/ml) and clofazimine (0.03–0.25 μg/ml). QC ranges could not be established for nicotinamide (pyrazinamide surrogate), prothionamide or ethionamide, which were assay non-performers. CONCLUSIONS : Using strict CLSI criteria, QC ranges against the MTB H37Rv reference strain were established for the majority of commonly used antituberculosis drugs, with a convenient 7H9 broth microdilution MIC method suitable for use in resource-limited settings.All participating laboratories received funds for this study from Janssen Pharmaceuticals except the Reference Laboratory, Division of TB Elimination, United States Centers for Disease Control and Prevention, Atlanta, GA, USA. Support for medical writing assistance was provided by Janssen Pharmaceuticals.http://jcm.asm.org2017-06-30hb2017Medical Microbiolog

Laboratory Diagnosis of Mycobacterial Infections: New Tools and Lessons Learned

Even in the 21st century, tuberculosis continues to be a problem. Although the number of cases continues gradually to decrease in the United States, cases get more difficult to treat, specifically those that are multiple-drug resistant. Infection of one-third of the world's population ensures that tuberculosis will not disappear in the near future. In light of this, it will be useful to know the goals for the health care system and how these goals may be accomplished. Laboratory testing in the mycobacteriology field is experiencing more changes today than ever before. Determining what assays will be most useful to the clinician is a challenge, and acceptance of the new technology by the medical community an even greater one. Clinicians must use the best available resources to determine the most appropriate care for their patients and work together with the laboratory to ensure that the communication channels are open. This review focuses on current state-of-the-art resources useful for accurate and rapid laboratory diagnosis of mycobacterial infection