Tolerance of Pseudomonas aeruginosa in in vitro biofilms to high level peracetic acid disinfection

Ayorinde Akinbobola, Leighann Sherry, William MacKay, Gordon Ramage, Craig Williams

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35 Citations (Scopus)
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Biofilm has been suggested as a cause of disinfection failures in flexible endoscopes where no lapses in the decontamination procedure can be identified. To test this theory, the activity of peracetic acid (PAA), one of the commonly used disinfectants in the reprocessing of flexible endoscopes, was evaluated against both planktonic and sessile communities of Pseudomonas aeruginosa.

To investigate the ability of P. aeruginosa biofilm to survive high level PAA disinfection.

The susceptibility of planktonic cells of P. aeruginosa and biofilms 24, 48, 96 and 192 h old to PAA was evaluated by estimating their viability using resazurin viability and plate count methods. The biomass of the P. aeruginosa biofilms was also quantified using crystal violet assay. Planktonic cells of P. aeruginosa were treated with 5 – 30 ppm concentration of PAA in the presence of 3.0 g/L of Bovine serum albumin (BSA) for 5 min. Biofilms of P. aeruginosa were also treated with various PAA concentrations (100 - 3000 ppm) for 5 min.

Planktonic cells of P. aeruginosa were eradicated by 20 ppm of PAA, whereas biofilms showed an age dependent tolerance to PAA, and 96 h old biofilm was only eradicated at PAA concentration of 2500 ppm.


96 h old P. aeruginosa biofilm survives 5 min treatment with 2000 ppm of PAA, which is the working concentration used in some endoscope washer disinfectors. This implies that disinfection failure of flexible endoscopes could occur when biofilms are allowed to build up in the lumens of endoscopes.
Original languageEnglish
Pages (from-to)162-168
Number of pages7
JournalJournal of Hospital Infection
Issue number2
Early online date23 Jun 2017
Publication statusE-pub ahead of print - 23 Jun 2017


  • Peracetic acid
  • disinfectant
  • biofilm
  • resistance


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