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Antiseptic Stewardship for Instrument Disinfectants
Abstract
Instrument disinfectants can be based on different types of biocidal active substances such as benzalkonium chloride, DDAC, glutaraldehyde, hydrogen peroxide, peracetic acid and sodium hypochlorite. Validated reprocessing of non-critical and semi-critical medical devices is expected to provide a health benefit to patients. A low adaptive response combined with a frequently observed inhibition of biofilm formation and removal of existing biofilm cannot be attributed to any of the biocidal active substances. Overall, the use of peracetic acid on surfaces of instruments where biofilm formation is to be inhibited (e.g. flexible endoscopes) seems to be the most appropriate option due to the low selection pressure, mainly inhibition of biofilm formation and mainly moderate removal of biofilm. Hydrogen peroxide and sodium hypochlorite also have a low selection pressure and can moderately remove biofilm, but they could also increase biofilm formation in a relevant number of species. They appear to be suitable for use on instrument surfaces where the enhancement of biofilm formation is of minor importance. Benzalkonium chloride seems to be the least suitable biocidal active substance, taking into account the often observed strong and stable adaptive response, the cross-tolerance with some other biocidal active substances and the inconclusive effect on biofilm formation and removal.
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Background
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.
Aim
To investigate the ability of P. aeruginosa biofilm to survive high level PAA disinfection.
Method
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.
Results
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.
Conclusion
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.
All invasive procedures involve contact by a medical device or surgical instrument with a patient's sterile tissue or mucous membranes. The level of disinfection or sterilization is dependent on the intended use of the object: critical (items that contact sterile tissue such as surgical instruments), semicritical (items that contact mucous membrane such as endoscopes), and noncritical (devices that contact only intact skin such as stethoscopes) items require sterilization, high-level disinfection and low-level disinfection, respectively. Cleaning must always precede high-level disinfection and sterilization.
Antiseptics are essential to infection prevention as part of a hand hygiene program as well as several other uses such as surgical hand antisepsis and pre-operative skin preparation.
SUMMARY Flexible endoscopy is a widely used diagnostic and therapeutic procedure. Contaminated endoscopes are the medical devices frequently associated with outbreaks of health care-associated infections. Accurate reprocessing of flexible endoscopes involves cleaning and high-level disinfection followed by rinsing and drying before storage. Most contemporary flexible endoscopes cannot be heat sterilized and are designed with multiple channels, which are difficult to clean and disinfect. The ability of bacteria to form biofilms on the inner channel surfaces can contribute to failure of the decontamination process. Implementation of microbiological surveillance of endoscope reprocessing is appropriate to detect early colonization and biofilm formation in the endoscope and to prevent contamination and infection in patients after endoscopic procedures. This review presents an overview of the infections and cross-contaminations related to flexible gastrointestinal endoscopy and bronchoscopy and illustrates the impact of biofilm on endoscope reprocessing and postendoscopic infection.
In this experimental study we compared the previous descontamination efficacy of the medical surgical materials by the use of chemical disinfectants and the mechanical cleaning with water and soap, as well as verified the organic material interference in these procedures. To carry out this study, we used surgical pincers under contamination with: Staphylococcus aureus ATCC-6538, Salmonella cholerae suis ATCC-10708, and Pseudomonas aeruginosa ATCC-15442 in presence and absence of organic matter (fetal bovine serum). The following treatments: glutaraldehyde 2%, sodium hypochlorite 1%, hydrogen peroxide 6%, alcohol 70% and the mechanical cleaning with water and soap were compared with eight repetitions in a total of 480 observations. In the described conditions, the disinfectants had a good efficacy in the previous descontamination of the medical surgical materials and a less inactivation by the organic material. The mechanical cleaning with water and soap showed a reduction of the microrganism to safe levels, considered adequate for previous descontamination.
All invasive procedures involve contact between a medical device or surgical instrument and a patient's sterile tissue or
mucous membranes. A major risk of all such procedures is the introduction of pathogenic microbes that could lead to infection.
Failure to properly disinfect or sterilize reusable medical equipment carries a risk associated with breach of the host barriers.
The level of disinfection or sterilization is dependent on the intended use of the object: critical items (such as surgical
instruments, which contact sterile tissue), semicritical items (such as endoscopes, which contact mucous membranes), and noncritical
items (such as stethoscopes, which contact only intact skin) require sterilization, high-level disinfection, and low-level
disinfection, respectively. Cleaning must always precede high-level disinfection and sterilization. Users must consider the
advantages and disadvantages of specific methods when choosing a disinfection or sterilization process. Adherence to these
recommendations should improve disinfection and sterilization practices in health care facilities, thereby reducing infections
associated with contaminated patient-care items.
To review recent publications relevant to hospital disinfection (and cleaning) including the reprocessing of medical instruments.
The key question as to whether the use of disinfectants on environmental surfaces rather than cleaning with detergents only reduces nosocomial infection rates still awaits conclusive studies. New disinfectants, mainly peroxygen compounds, show good sporicidal properties and will probably replace more problematical substances such as chlorine-releasing agents. The safe reprocessing of medical devices requires a well-coordinated approach, starting with proper cleaning. New methods and substances show promising activity for preventing the transmission of prions. Different aspects of virus inactivation have been studied, and the transmissibility, e.g. of norovirus, shows the need for sound data on how different disinfectant classes perform. Biofilms or other forms of surface-adherent organisms pose an extraordinary challenge to decontamination. Although resistance to biocides is generally not judged to be as critical as antibiotic resistance, scientific data support the need for proper use, i.e. the avoidance of widespread application, especially in low concentrations and in consumer products.
Chemical disinfection of heat-sensitive instruments and targeted disinfection of environmental surfaces are established components of hospital infection control. To avoid danger to staff, patients and the environment, prudent use as well as established safety precautions are required. New technologies and products should be evaluated with sound methods. As emerging resistant pathogens will challenge healthcare facilities in the future even more than at present, there is a need for well-designed studies addressing the role of disinfection in hospital infection control.
Anforderungen an die Hygiene bei der Aufbereitung von Medizinprodukten
- Robert Krinko
- Bfarm Koch Institut Und