Exposure Time for Effectiveness of HLD for Endoscope Reprocessing Should be Reconsidered

The bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Chino, et al. (2017) investigated the bactericidal effect of a high-level disinfectant, peracetic acid (PAA), against Staphylococcus aureus and Pseudomonas aeruginosa biofilm models in vitro.

S. aureus and P. aeruginosa biofilms were cultured at 35 degrees C for seven days with catheter tubes. The following high-level disinfectants (HLDs) were tested: 0.3% PAA, 0.55% ortho-phthalaldehyde (OPA), and 2.0% alkaline-buffered glutaraldehyde (GA). Biofilms were exposed to these agents for 1–60 minutes and observed after 5 minutes and 30 minutes by transmission and scanning electron microscopy. A student’s t test was performed to compare the exposure time required for bactericidal effectiveness of the disinfectants.

PAA and GA were active within 1 minute and 5 minutes, respectively, against S. aureus and P. aeruginosa biofilms. OPA took longer than 10 minutes and 30 minutes to act against S. aureus and P. aeruginosa biofilms, respectively (p < 0.01). Treatment with PAA elicited changes in cell shape after 5 minutes and structural damage after 30 minutes.

Amongst the HLDs investigated, the researchers concluded that PAA elicited the most rapid bactericidal effects against both biofilms. Additionally, treatment with PAA induced morphological alterations in the in vitro biofilm models, suggesting that PAA exerts fast-acting bactericidal effects against biofilms associated with endoscopy-related infections. These findings indicate that the exposure time for bactericidal effectiveness of HLDs for endoscope reprocessing in healthcare settings should be reconsidered.

Chino T, et al. Morphological bactericidal fast-acting effects of peracetic acid, a high-level disinfectant, against Staphylococcus aureus and Pseudomonas aeruginosa biofilms in tubing. Antimicrobial Resistance & Infection Control. 2017;6:122

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