title: Norfloxacin and ursolic acid: in vitro association and postantibiotic effect against Staphylococcus aureus.
abstract: OBJECTIVE
  We investigated the effectiveness in vitro of the association between norfloxacin (NOR) and ursolic acid (UA) against Staphylococcus aureus.
  
  
  RESULTS
  The minimal inhibitory concentrations (MICs), the minimal bactericidal concentrations, the bacterial killing and the postantibiotic effect (PAE) of NOR and UA were determined both singly and in combination. A synergistic interaction was observed against Staph. aureus ATCC 29213: the mean PAEs were 3 h for NOR, -1.2 h for UA (1 × MIC) and 2.0 h for UA (2 × MIC). Synergism was observed with longer PAEs and postantibiotic sub-MIC effects after NOR/UA exposure. UA was also active against clinical isolates and methicillin-resistant Staph. aureus.
  
  
  CONCLUSIONS
  The application of antimicrobial combinations may address the rising resistance to established classes of both systemic and topical agents.
  
  
  CONCLUSIONS
  In vitro interactions between NOR and UA may contribute to the development of novel topical agents for the treatment of skin infections as well as for topical formulations.
authors: Pharmaco-Biological Department, University of Messina, Messina, Italy.
authors: A
authors: A
authors: Filocamo
authors: C
authors: C
authors: Bisignano
authors: M
authors: M
authors: D'Arrigo
authors: G
authors: G
authors: Ginestra
authors: G
authors: G
authors: Mandalari
authors: E M
authors: EM
authors: Galati