title: In vitro culture conditions affecting minimal inhibitory concentration of bedaquiline against M. tuberculosis.
abstract: OBJECTIVE
  In developing a standardized drug susceptibility test for bedaquiline, it is very important to know which parameters might impact its activity in vitro and result in false resistance of the bacterium to bedaquiline. We aimed to assess the impact of different in vitro conditions on the minimal inhibitory concentration (MIC) of bedaquiline against Mycobacterium tuberculosis H37Rv reference strain.
  
  
  METHODS
  The MIC of M. tuberculosis H37Rv strain was determined under different conditions such as inoculum size, pH, temperatures, log and stationary phase cultures, protein concentration, Tween 80 concentration, and labware plastics.
  
  
  RESULTS
  Increases in bedaquiline MIC were observed with variations in inoculum size for M. tuberculosis H37Rv on agar or in broth, in protein concentration and labware plastics on agar, and with variations in pH and Tween 80 concentrations in broth.
  
  
  CONCLUSIONS
  In order to obtain reproducible MIC results, bedaquiline MIC should be assessed using polystyrene plates or tubes, at pH 7, with a Tween 80 concentration of 0.02%, without protein enrichment and with an inoculum size up to 10(7) colony-forming unit (CFU)/mL on 7H11 agar or with 10(5)CFU/mL in 7H9 broth.
authors.affiliation: Janssen Infectious Diseases BVBA, Turnhoutseweg 30, 2340 Beerse, Belgium. Electronic address: nlounis@its.jnj.com.
authors.forename: N
authors.initials: N
authors.lastname: Lounis
authors.affiliation: Janssen Infectious Diseases BVBA, Turnhoutseweg 30, 2340 Beerse, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Vranckx
authors.affiliation: Janssen Infectious Diseases BVBA, Turnhoutseweg 30, 2340 Beerse, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Gevers
authors.affiliation: Janssen Research & Development, LLC, Titusville, NJ, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kaniga
authors.affiliation: Janssen Infectious Diseases BVBA, Turnhoutseweg 30, 2340 Beerse, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Andries
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques / Q000295:instrumentation / Q000379:methods*; D003470:Culture Media / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D064687:Diarylquinolines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests / Q000295:instrumentation / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development; D010047:Ovalbumin / Q000494:pharmacology; D011126:Polypropylenes; D011136:Polysorbates / Q000494:pharmacology; D011137:Polystyrenes; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013696:Temperature
chemical_list: D000995:Antitubercular Agents; D003470:Culture Media; D003902:Detergents; D064687:Diarylquinolines; D011126:Polypropylenes; D011136:Polysorbates; D011137:Polystyrenes; D012710:Serum Albumin, Bovine; C493870:bedaquiline; D010047:Ovalbumin
keywords: Bacterial inoculum; Bedaquiline; Bédaquiline; Inoculum bactérien; TMC207