title: Reduction of the neutralisation time during antimicrobial activity testing of disinfectants according to European Standards.
abstract: BACKGROUND
  Evaluation of the biocidal activity of chemical disinfectants and antiseptics according to European Standards (EN) is based on determination of the reduction of the number of viable test microorganisms under defined conditions.
  
  
  OBJECTIVE
  The objective of this study was to investigate whether reducing the neutralization time required following declared product contact times for the tested microorganisms yields method validations.
  
  
  METHODS
  This study was conducted on 14 products containing active substances from different chemical groups: alcohols, aldehydes, biguanides, quaternary ammonium compounds, phenols, amines derivatives, oxidizing agents. These products were tested according to phase 1 tests: EN 1040:2005 and EN 1275:2005 and then according to phase 2, step 1 tests: Draft EN 13727:2005 and EN 13624:2003. Biocidal activity was evaluated using the following test organisms: S. aureus ATCC 6538, P. aeruginosa ATCC 15442, E. coli NCTC 10538, E. coli ATCC 10536, E. hirae ATCC 10541, C. albicans ATCC 10231 and A. brasiliensis ATCC 16404.
  
  
  RESULTS
  Validation C results for all products and tested microorganism strains were at least half of the density of the suspension for validation (Nvo) after only 10 s of neutralization. Furthermore, results from test procedures performed in parallel were also positive except 5 products toward A. brasiliensis.
  
  
  CONCLUSIONS
  The results of our study confirm that the contact time described in the European Standards phase 1: EN 1040 and EN 1275, as well as phase 2, step 1: Draft EN 13727 and EN 13624 can be precisely determined in spite of reducing the neutralization time from 5 minutes to even 10 seconds.
authors.affiliation: Department of Antibiotics and Microbiology, National Medicines Institute, Warsaw, Poland. s.tyski@nil.gov.pl
authors.forename: Stefan
authors.initials: S
authors.lastname: Tyski
authors.forename: Ewa
authors.initials: E
authors.lastname: Bocian
authors.forename: Wanda
authors.initials: W
authors.lastname: Grzybowska
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D013293:Enterococcus faecalis / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D005062:European Union; D006801:Humans; D008828:Microbiological Techniques / Q000379:methods; D009500:Neutralization Tests / Q000379:methods*; D011044:Poland; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D015203:Reproducibility of Results; D013211:Staphylococcus aureus / Q000187:drug effects; D013997:Time Factors
chemical_list: D000891:Anti-Infective Agents, Local; D004202:Disinfectants