title: The polyketide synthase-associated multidrug tolerance in Mycobacterium intracellulare clinical isolates.
abstract: BACKGROUND
  Intrinsic multidrug resistance of the Mycobacterium avium-intracellulare complex presents a serious problem in the treatment of the diseases caused by these bacteria. Recently, it was shown that deletion of a polyketide synthase, Pks12, in an M. avium laboratory strain decreases this intrinsic resistance.
  
  
  METHODS
  We investigated Pks12 expression and its enzymatic activity in 9 clinical isolates of M. intracellulare, and compared their drug susceptibilities to 4 drugs. Also, we made pks12-disrupted M. bovis bacillus Calmette-Guérin (BCG) mutant and its complemented strain. Using these BCG and M. intracellulare strains, we observed intracellular accumulation of ethidium bromide (EtBr).
  
  
  RESULTS
  We found positive correlations between Pks12 and drug resistance for all of the antibiotics tested. The drug susceptible M. intracellulare strain showed higher EtBr accumulation. Consistent with this, EtBr was much more accumulated in pks12-disrupted BCG than wild-type or the complemented strains.
  
  
  CONCLUSIONS
  Collectively, these results suggest that Pks12 controls the multidrug resistance in part through intracellular drug accumulation.
authors.affiliation: Laboratory of Cell Regulation, Institute for Virus Research, Kyoto University, Kyoto, Japan. i_matsun@virus.kyoto-u.ac.jp
authors.forename: Isamu
authors.initials: I
authors.lastname: Matsunaga
authors.forename: Shinji
authors.initials: S
authors.lastname: Maeda
authors.forename: Shinji
authors.initials: S
authors.lastname: Meda
authors.forename: Noboru
authors.initials: N
authors.lastname: Nakata
authors.forename: Nagatoshi
authors.initials: N
authors.lastname: Fujiwara
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004996:Ethidium / Q000737:chemistry; D006801:Humans; D008826:Microbial Sensitivity Tests; D015269:Mycobacterium avium Complex / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification; D015270:Mycobacterium avium-intracellulare Infection / Q000382:microbiology; D009163:Mycobacterium bovis / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D048630:Polyketide Synthases; D004996:Ethidium