title: Possible mechanisms for the relative efficacies of ortho-phthalaldehyde and glutaraldehyde against glutaraldehyde-resistant Mycobacterium chelonae.
abstract: OBJECTIVE
  This investigation compared glutaraldehyde (GTA)-sensitive and -resistant strains of Mycobacterium chelonae and examined the effects of pretreatment of GTA-sensitive and -resistant strains of Myco. chelonae with chemical agents that interfere with cell wall synthesis.
  
  
  RESULTS
  When exposed to 2% (v/v) GTA at 25 degrees C, GTA-resistant strains of Myco. chelonae dried on to glass carriers were not inactivated to any significant extent. By contrast, GTA-sensitive strains of Myco. chelonae and a strain of Myco. terrae suffered a > 6 log reduction in viability in 5 min. However, ortho-phthalaldehyde (OPA; 0.5% w/v) achieved a corresponding inactivation against two GTA-resistant strains within 5-10 and 10-20 min, respectively. Electron microscopy, using a non-aldehyde fixation process and also negative staining, failed to detect any extensive changes in GTA-sensitive and -resistant cultures exposed to GTA or OPA. Thin-layer chromatography was unsuccessful in detecting differences between GTA-resistant and -sensitive strains of Myco. chelonae. However, pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility further to OPA but not to GTA.
  
  
  CONCLUSIONS
  Ortho-phthalaldehyde is an effective new biocidal agent that, at its in-use concentration, is rapidly bactericidal to non-sporulating bacteria, including GTA-sensitive and -resistant mycobacteria.
  
  
  CONCLUSIONS
  Pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility to OPA but not to GTA.
authors.affiliation: Welsh School of Pharmacy, Cardiff University, Cardiff, Wales, UK.
authors.forename: S E
authors.initials: SE
authors.lastname: Walsh
authors.forename: J Y
authors.initials: JY
authors.lastname: Maillard
authors.forename: A D
authors.initials: AD
authors.lastname: Russell
authors.forename: A C
authors.initials: AC
authors.lastname: Hann
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D002855:Chromatography, Thin Layer; D003523:Cycloserine / Q000494:pharmacology; D004347:Drug Interactions; D004352:Drug Resistance, Microbial; D004977:Ethambutol / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D016926:Mycobacterium chelonae / Q000187:drug effects* / Q000648:ultrastructure; D009764:o-Phthalaldehyde / Q000494:pharmacology*
chemical_list: D000995:Antitubercular Agents; D009764:o-Phthalaldehyde; D004977:Ethambutol; D003523:Cycloserine; D005976:Glutaral