title: Selective sensitization of bacteria to peroxide damage associated with fluoride inhibition of catalase and pseudocatalase.
abstract: Fluoride and sulfide are known inhibitors of heme catalases in acid environments. Staphylococcus aureus H cells were found to be sensitized by fluoride or sulfide to H2O2 killing at acid pH values in the range of 3.5 to 4.0, and catalase activity was reduced concomitantly. In contrast, fluoride had little effect on H2O2 killing of Streptococcus mutans GS-5, which has fluoride-insensitive peroxidase activity, but still is more sensitive to H2O2 than is S. aureus in the absence of fluoride. Fluoride but not sulfide was inhibitory also for the Mn-containing, non-heme pseudocatalase of Lactobacillus plantarum ATCC 14431 over a wide pH range, and this inhibitory effect was reflected in enhanced H2O2 killing in the presence of fluoride. In addition, we found that catalase-positive S. aureus or Neisseria sicca could protect catalase-negative S. mutans against killing by H2O2 in mixed suspensions, but protection was compromised by fluoride or sulfide under acid conditions. Thus, catalase-positive organisms could protect a catalase-negative organism against peroxide damage, but inhibition of catalase reduced protection. These findings are pertinent to the widespread use of fluoride and peroxide in oral health care products.
authors.affiliation: Department of Microbiology & Immunology, University of Rochester Medical Center, Rochester, New York 14642-8672, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Phan
authors.forename: A M
authors.initials: AM
authors.lastname: Kirsch
authors.forename: R E
authors.initials: RE
authors.lastname: Marquis
mesh_terms: D000143:Acids; D001419:Bacteria / Q000187:drug effects* / Q000201:enzymology; D002374:Catalase / Q000037:antagonists & inhibitors*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005459:Fluorides / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000037:antagonists & inhibitors; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000187:drug effects; D009243:NAD / Q000037:antagonists & inhibitors; D009343:Neisseria / Q000187:drug effects; D016877:Oxidants / Q000494:pharmacology*; D010544:Peroxidases / Q000037:antagonists & inhibitors; D013211:Staphylococcus aureus / Q000187:drug effects; D013295:Streptococcus mutans / Q000187:drug effects; D013440:Sulfides / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors
chemical_list: D000143:Acids; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D016877:Oxidants; D013440:Sulfides; D009243:NAD; D006861:Hydrogen Peroxide; D010544:Peroxidases; C038109:pseudocatalase; C021845:NAD+ peroxidase; D002374:Catalase; D013482:Superoxide Dismutase; D005459:Fluorides