Greg Wideman from South West Ontario Veterinary Services, Does The Use Of Disinfectant Contribute to Development Of AMR?


Cleaning  and  disinfection  is  an  integral component of livestock production. There is  some  evidence,  based  on  laboratory experiments, that suggests that exposure of bacteria   to   sub-inhibitory   concentrations   of disinfectants may facilitate selection for disinfectant and  antimicrobial  resistance.  Laboratory-based experiments have shown that step-wise exposure of initially  susceptible  bacteria  to  sub-inhibitory concentrations of benzalkoniumchloride, chlorhexidine,  triclosan  and  some  commercial disinfectants may lead to decreased susceptibility to either antibiotics or disinfectants.The   recommended   concentrations   of   farm disinfectants  is  normally  well  above  the  minimum inhibitory  concentration  (MIC)  of  disease  causing agents. Because  commercial  disinfectants  often contain  more  than  one  type  of  active  disinfectant component  having  different  antimicrobial  mode  of action   the   development   of   resistance   at recommended rates should be highly unlikely. In the real  world,  however,  bacteria  may  be  exposed  to disinfectants at sub-inhibitory concentrations due to mixing  errors,  the  presence  of  residual  organic debris that is not removed during cleaning or to the dilution   effect   of   remaining   rinse   water.

Researchers  wanted  to  look  for “real  world” evidence  for  the  likelihood  that  sub-inhibitory concentrations could lead to selection of strains of E. coli with increased disinfectant and antimicrobial resistance.The results of this study were as follows:

  • As  a  base  level,  there  was  a  high  resistance prevalence     (>50%)     for     ampicillin, sulfamethoxazole, trimethoprim and tetracycline for  both  poultry  and  pigs.  Ciprofloxacin resistance  prevalence  was  primarily  a  broiler house issue.
  • Disinfectant   susceptibility   results   were homogenously  distributed  within  a  very  small concentration range.
  • All  E.  coli  strains  were  susceptible  to  in-use concentrations of formaldehyde, benzalkoniumchloride  and  a  formulation  of peracetic acid and hydrogen peroxide, indicating that  the  practical  use  of  disinfectants  did  not select for disinfectant resistance.
  • There  was  no  evidence  for  the  selection  of antibiotic  resistant  bacteria  through  the  use  of disinfectants in agricultural environments.

Take Home Message

  • The  use  of  disinfectants  under  practical  farm conditions does not appear to increase the risk of   either   disinfectant   or   antimicrobial resistance in bacteria.
  • Although  these  results  are  comforting  it  is important  to  recognize  that  this particular  study  was limited to one geographic region and one type of bacteria (E. coli)

Submitted by Greg Wideman, DVM


Ref: Maertens H, De Reu K, Meyer E, Van Coillie E, Dewulf J.Limited association between disinfectant use and either antibiotic or disinfectant susceptibility of Escherichia coli in both poultry and pig husbandry.BMC Vet Res. 2019 Sep 2;15(1):310. doi: 10.1186/s12917-019-2044-0


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