Morphological bactericidal fast-acting effects of peracetic acid, a high-level disinfectant, against Staphylococcus aureus and Pseudomonas aeruginosa biofilms in tubing

T Chino,K Moriya,Y Morishita,Y Nukui

doi:10.1186/s13756-017-0281-1

Abstract

BackgroundThe bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Here, we investigated the bactericidal effect of a high-level disinfectant, peracetic acid (PAA), against Staphylococcus aureus and Pseudomonas aeruginosa biofilm models in vitro.MethodsS. aureus and P. aeruginosa biofilms were cultured at 35 °C for 7 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 min and observed after 5 min and 30 min 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.ResultsPAA and GA were active within 1 min and 5 min, respectively, against S. aureus and P. aeruginosa biofilms. OPA took longer than 10 min and 30 min to act against S. aureus and P. aeruginosa biofilms, respectively (p < 0.01). Treatment with PAA elicited changes in cell shape after 5 min and structural damage after 30 min.ConclusionsAmongst the HLDs investigated, 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.

Highlights

The bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination
Chemical disinfectant preparation Each disinfectant was diluted with sterile water according to manufacturers’ instructions: 0.3% peracetic acid (PAA) (6% Acecide; Saraya Co., Ltd., Osaka, Japan), 0.55% OPA, 2.0% GA (20% Sterihyde; Maruishi Pharmaceutical Co., Ltd., Osaka, Japan) for endoscopy High-level disinfection (HLD), or 0.1% sodium hypochlorite solution (NaClO; 1% Yakulax; Yakuhan Pharmaceutical Co., Ltd., Hokkaido, Japan); chlorine levels that are safe for environmental disinfection at comparable standard formulations were used
Biofilm resistance to disinfectants The bactericidal effects of 0.3% PAA, 0.55% OPA, 2.0% GA, and 0.1% Sodium hypochlorite solution (NaClO) against 12 S. aureus and 12 P. aeruginosa biofilms accumulated on tubing for 7 days was tested

Summary

Introduction

The bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Endoscopy-related infections caused by biofilm adhesion within the narrow luminal cavities of endoscope channels are attributed to inadequate cleaning routines and ineffective disinfection procedures [5, 6] despite adherence to guideline recommendations [7, 8]. These are often reported in conjunction with pseudooutbreaks of biofilm-producing bacteria [9,10,11]. Biofilms are recalcitrant to endoscope reprocessing, resulting in infection by P. aeruginosa and Mycobacterium chelonae isolates, such as those with high resistance to glutaraldehyde (GA) [12, 13]

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