Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes?

Table 1 Typical sequence of steps for manual and automatic reprocessing of flexible endoscopes including the typical duration of the various cleaning steps

Manual processing	Automatic processing
Pre-cleaning the outer surface with a detergent-soaked single-use gauze and rinsing all channels with the cleaning agent, usually for 2 min
Brush-cleaning all accessible channels with a suitable brush, usually for 3 min
	Rinsing
Chemical cleaning; filling all channels with the cleaning agent, allowing the cleaning agents to persist inside the channel for approximately 5 min
Rinsing, usually for 1 min
Disinfection
Final rinsing
Drying

Table 2 Outbreaks and pseudo-outbreaks reported in connection with biofilm or peracetic acid-based processing of flexible endoscopes

Number/type of infection(s)	Pathogen(s)	Type of endoscopic procedure	Reason for outbreak / pseudo-outbreak	Peracetic acid-based formulations were used for	Ref.
None (pseudo-outbreak)	Pseudomonas aeruginosa	Gastroscopy, bronchoscopy	Suboptimal duration of glutaraldehyde application during disinfection; “resistance” to glutaraldehyde may have been enhanced by manual cleaning with peracetic acid-based disinfectant[214]	Cleaning step	[202]
2: infection (not further specified)3: colonization	OXA-48 Klebsiella pneumoniae	Bronchoscopy	A problem with the washer disinfector or the cleaning procedure was assumed as the reason	Cleaning step and disinfection step (Gastmeier P, personal communication)	[203]
4: pneumonia (3 cases); colonization (1 case)	MDR Pseudomonas aeruginosa	Gastroscopy	Insufficient initial cleaning, shortening of the immersion time and brushing time, insufficient channel flushing, and inadequate drying prior to storage	Disinfection step	[124]
4: bacteraemia, biliary tract infection, respiratory tract infection9: colonisation	KPC-2 Klebsiella pneumoniae	Duodenoscopy	Contaminated duodenoscope; reason for outbreak: inadequate cleaning	Disinfection step	[204]
8: bloodstream infection4: biliary tract infection4: colonization	ESBL Klebsiella pneumoniae (CTX-M-15)	ERCP	Insufficient manual cleaning, insufficient drying after processing	Disinfection step	[125]
3: sepsis	Pseudomonas aeruginosa	ERCP	Presence of biofilm on undamaged channels	Disinfection step (Kovaleva J; personal communication)	[205]
5: infection (not further specified) 9: colonization	OXA-48 Klebsiella pneumoniae	Duodenoscopy	One endoscope had probably a defect resulting in insufficient disinfection	Disinfection step (Gastmeier P, personal communication)	[203]
18: pulmonary infection (4 cases, one of them died); colonization (14 cases)	Imipenem-resistant Pseudomonas aeruginosa	Bronchoscopy	Incorrect connectors joining the bronchoscope suction channel to the STERIS SYSTEM 1 processor	“Automatic processing”	[206]
2: bacteremia and biliary tract infection 4: colonization	KPC-2 Klebsiella pneumoniae	Gastroscopy	Delayed pre-wash resulting in drying of the gastroscope; short drying period after the peracetic acid treatment resulting in incomplete drying	“Wash”	[207]

ERCP: Endoscopic retrograde cholangiopancreatography.

Table 3 Adverse effects after processing with peracetic acid after endoscopy

Number of cases	Type of reaction	Possible explanation	Ref.
10	Colitis	Unclear, reprocessing with PAA, but afterwards channels were flushed with hydrogen peroxide	[210]
1	Colitis	PAA residues in the biopsy suction channel	[215]
2	Colitis	Defect of automatic rinsing of a channel	[216]
1	Colitis	Channel not flushed	[217]
1	Colitis	Inadequate rinsing of a channel	[212]
No number provided	Pseudolipomatosis	Air channels not rinsed	[218]
4	Colitis	Programming error in the automatic disinfection device, related to the air/water channels	[219]
12	Colonic mucosal pseudolipomatosis	Rinsing was not done as recommended	[220]

Table 4 Overview of evidence-based guidelines for processing flexible endoscopes, focusing on the use of peracetic acid during the cleaning step

Institution	Guidelines	Year	Use of peracetic acid for cleaning
AORN	Recommended practices for cleaning and processing endoscopes and endoscope accessories[221,222]	2012	No recommendation
APIC	APIC guidelines for infection prevention and control in flexible endoscopy. Association for Professionals in Infection Control[223]	2000	No recommendation
APSIC	The ASEAN Guidelines for disinfection and sterilization of instruments in health care facilities[224]	2012	No recommendation
ASGE	Multisociety guidelines on reprocessing flexible gastrointestinal endoscopes: 2011[225,226]	2011	No recommendation
BC Ministry of Health	Best Practice Guidelines For Cleaning, Disinfection and Sterilization of Critical and Semi-critical Medical Devices[227]	2011	No recommendation
BSG	BSG Guidelines for Decontamination of Equipment for Gastrointestinal Endoscopy[228]	2008	No recommendation
CDC	Guidelines for Disinfection and Sterilization in Healthcare Facilities, 2008[229]	2008	No recommendation
ESGE/ESGENA	1ESGE/ESGENA Technical Note on Cleaning and Disinfection[230]	2003	Recommended
ESGE/ESGENA	ESGE-ESGENA guideline: Cleaning and disinfection in gastrointestinal endoscopy, update 2008[231]	2008	No recommendation
HPS	Endoscope Reprocessing: Guidance on the Requirements for Decontamination Equipment, Facilities and Management[232]	2007	No recommendation
JGETS	Guidelines for cleaning and disinfecting endoscopes - Second edition[233]	2004	No recommendation
Public Health Agency of Canada	Infection Prevention and Control Guideline for Flexible Gastrointestinal Endoscopy and Flexible Bronchoscopy[234]	2010	No recommendation
RKI	2Hygiene requirements for reprocessing of medical devices[235]	2001	No recommendation
RKI	Hygiene requirements for reprocessing of medical devices[236]	2012	Not recommended
SGNA	Standards of Infection Control in Reprocessing of Flexible Gastrointestinal Endoscopes[237]	2013	No recommendation
WGO/OMED	WGO/OMED Practice Guideline Endoscope Disinfection[238]	2005	Recommended
WGO/WEO	Endoscope disinfection - a resource-sensitive approach[239]	2011	No recommendation

¹These guidelines were updated in 2008 by guidelines[231];

²These guidelines were updated in 2012 by guidelines[236]. AORN: Association of periOperative Registered Nurses; APIC: Association for Professionals in Infection Control and Epidemiology; APSIC: Asia Pacific Society of Infection Control; ASGE: American Society for Gastrointestinal Endoscopy; BSG: British Society of Gastroenterology; CDC: Centers for Disease Control and Prevention; ESGE: European Society of Gastrointestinal Endoscopy; ESGENA: European Society of Gastroenterology and Endoscopy Nurses and Associates; HPS: Health Protection Scotland; JGETS: Japanese Gastroenterological Endoscopy Technicians Society; OMED: Organisation Mondiale d'Endoscopie Digestive/World Organization for Digestive Endoscopy; RKI: Robert Koch Institute; SGNA: Society of Gastroenterology Nurses and Associates, Inc; WEO: World Endoscopy Organization (former OMED); WGO: World Gastroenterology Organisation.

Table 5 Effects and possible outcomes of peracetic acid use for cleaning flexible endoscopes

Characteristic, reason for cleaning step	Effect of peracetic acid	Possible outcome, compared with classical cleaning
Removal of biofilm	Variable1	Insufficient removal of biofilm
Fixation of biofilm	Possible1	Fixation of biofilm to variable degrees
Removal of dried blood	Partial removal1	Insufficient removal of dried blood
Fixation of dried blood	Very likely	Fixation of dried blood to variable degrees
Fixation of brain tissue	Very likely	Strong fixation of nerve tissue, including prions
Adaptation of microorganisms surviving the cleaning step	Likely, especially in gram-negative bacteria	Insufficient efficacy of disinfection step, persistence of pathogens, beginning of biofilm formation
Cross-resistance to other biocidal compounds as a result of exposure to sublethal peracetic acid concentrations	Possible	Insufficient efficacy of disinfection step, persistence of pathogens, beginning of biofilm formation

¹Depending on the formulation.

Table 6 Practical tips to ensure optimal cleaning of flexible endoscopes

Clinical practice tip	Major advantage	Ref.
Clean promptly after use	No drying of organic material such as blood	[77,207]
Follow the instructions of the endoscope manufacturer as closely as possible (e.g., type of brush or cleaning adapter)	Optimum cleaning of an entire channel
Prefer washer disinfectors with a monitoring system indicating channel blockage	A blocked channel cannot be cleaned adequately and is immediately identified; targeted brush cleaning may be necessary
Do not switch off the monitoring system for detection of blocked channels	Channels may be blocked and inadequately cleaned; personnel may not detect blocked channels with all possible implications for patient safety
Support by gastroenterologist	It is strongly recommended that the clinician fully understands the cleaning and disinfection steps and does not inhibit his or her staff's ability to perform them correctly	[240]
Allow external audits by local health authorities on the quality of processing including cleaning	Implementation of guidelines may be more successful if the local health authorities visit the endoscopy units and compare current practices with the relevant guidelines. This effect seems to be more easily achieved in in-patient rather than in out-patient endoscopy units	[241-243]