title: Effects of benzalkonium chloride on planktonic growth and biofilm formation by animal bacterial pathogens.
abstract: BACKGROUND
  Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation.
  
  
  OBJECTIVE
  In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated.
  
  
  METHODS
  Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant.
  
  
  RESULTS
  The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella.
  
  
  CONCLUSIONS
  Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation.
authors: Department of Pathobiology, School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Azizollah
authors: A
authors: Ebrahimi
authors: School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Majid
authors: M
authors: Hemati
authors: School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Ziba
authors: Z
authors: Shabanpour
authors: Department of Pathobiology, School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Saeed
authors: S
authors: Habibian Dehkordi
authors: Department of Pathobiology, School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Shahab
authors: S
authors: Bahadoran
authors: Department of Pathobiology, School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Sharareh
authors: S
authors: Lotfalian
authors: School of Veterinary Sciences, Shahrekord University, Shahrekord, IR Iran.
authors: Shahin
authors: S
authors: Khubani
keywords: Benzalkonium chloride; Biofilms; Salmonella; Staphylococcus; Streptococcus