title: pH influence on antibacterial efficacy of common antiseptic substances.
abstract: BACKGROUND
  Wound infection plays an important role in compromised wound healing. A high bioburden impairs healing and leads to formation of a chronic wound. Distinctly higher pH values were observed in chronic wounds compared to acute wounds. However, there is only limited knowledge of pH dependency on the antibacterial efficacy of common antimicrobial substances.
  
  
  METHODS
  This study investigated the pH influence on the antimicrobial efficacy of povidone (PVP)-iodine, silver nitrate, chlorhexidine, octenidine and polihexanide against Staphylococcus aureus and Pseudomonas aeruginosa using the agar diffusion test and microplate laser nephelometry.
  
  
  RESULTS
  The bactericidal activity of chlorhexidine and octenidine was mainly pH-independent in a pH range of 5.0-9.0. In contrast, polihexanide showed a significant efficacy increase at a higher pH. It was also found that the influence of the pH on antiseptics differs among species of bacteria. For instance, S. aureus exhibited an increasing sensitivity against silver nitrate with rising pH whereas the effect on P. aeruginosa was found to be distinctly decreased. The antimicrobial effect of PVP-iodine was strongly diminished with rising pH.
  
  
  CONCLUSIONS
  The shift towards higher pH values in chronic wounds compared to acute wounds makes it imperative to know whether the antimicrobial efficacy of applied antimicrobial substances is altered by different pH levels. The results suggest that application of polihexanide might be advantageous for the management of wound infections, as both S. aureus and P. aeruginosa exhibited an increased susceptibility with rising pH.
authors.affiliation: Department of Dermatology, University Hospital Center Jena, Jena, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Wiegand
authors.forename: Martin
authors.initials: M
authors.lastname: Abel
authors.forename: Peter
authors.initials: P
authors.lastname: Ruth
authors.forename: Peter
authors.initials: P
authors.lastname: Elsner
authors.forename: Uta-Christina
authors.initials: UC
authors.lastname: Hipler
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D058491:Bacterial Load; D001645:Biguanides / Q000494:pharmacology; D002710:Chlorhexidine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007097:Imines; D011206:Povidone-Iodine / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D011725:Pyridines / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local; D001645:Biguanides; D007097:Imines; D011725:Pyridines; C031233:polihexanide; D011206:Povidone-Iodine; C034213:octenidine; D002710:Chlorhexidine