Disinfection Validation

Manufacturers of reusable medical devices must provide written instructions for disinfection of the products between use to ensure that the device can be used safely for the purpose for which it is intended. Manufacturers are obligated under the Food and Drug Administration (FDA) labeling regulations (21 CFR 801) to have the suitability of these processes validated. 

LexaMed is an industry leader in designing and performing medical device disinfection validations. Every device is different therefore each program begins with generation of a unique protocol by an experienced project manager followed by study execution by trained microbiologists and chemists.  

The validation protocol and testing are developed and conducted in compliance with the following standards:

• AAMI TIR 12:20 Designing, testing, and labeling medical devices intended for processing by health care facilities: A guide for device manufacturers
• AAMI TIR 30 (ST98 draft) A compendium of processes, materials, test methods, and acceptance criteria for cleaning reusable medical devices
• ISO 17664 Processing of health care products—Information to be provided by the medical device manufacturer for the processing of medical devices
• FDA guidance document Reprocessing Medical Devices in Health Care Settings: Validation Methods and Labeling

The efficacy of the disinfection process is conducted to validate one of three categories of disinfection. The FDA defines the categories based on the resistance of microorganisms to the disinfectant chosen.  

• Low-Level Disinfection: A lethal process utilizing an agent the kills vegetative forms of bacteria, some fungi, and lipid viruses. Appropriate for non-critical devices and non-patient contact surfaces.
• Intermediate-Level Disinfection: A lethal process utilizing an agent that kills viruses, mycobacteria, fungi, and vegetative bacteria, but no bacterial spores. Appropriate for non-critical patient contact devices, items that contact intact skin, environmental/medical equipment not intended to come into direct patient contact.
• High-Level Disinfection: A lethal process utilizing a sterilant under less than sterilizing conditions. The process kills all forms of microbial life except for large numbers of bacterial spores. The minimum treatment recommended for semi-critical devices.

Both the FDA and ISO documents categorize medical devices using the modified Spaulding Classification. Based on the intended use of the device, an appropriate disinfectant will be chosen.

• Critical Devices: Introduced directly into the human body, into the bloodstream or other normally sterile areas of the body, and sterile fluid pathways. Must be sterile at the time of use.
• Semi-Critical Devices: Contact intact mucous membranes or nonintact skin of patient during use but does not penetrate the blood barrier or sterile areas of the body. High-Level Disinfection recommended.
• Non-Critical Devices: Contacts only intact skin without penetration or does not directly contact the patient but can be contaminated during use. Intermediate or Low-Level Disinfection required depending on potential soils/use.

 

Protocol Development

Working closely with the study sponsor, the LexaMed project manager will attain an understanding of the device and the manufacturer’s disinfection instructions. Using this information, a protocol will be generated that will ensure all elements of the various standards are properly incorporated including things such as description of end-of-life conditioning, appropriate challenge organisms with justification and acceptance criteria for the chosen markers. The study sponsor will be asked to review and approve the protocol prior to study initiation.

 

End-of-life Conditioning

As stated in the guidance documents it is important that devices used for validation testing are reflective of their end of life condition in order to represent worst case conditions for disinfection. Prior to use for testing, devices should be cycled through the typical number of cleaning and sterilization/disinfection cycles they are expected to be exposed to. Clients may choose to conduct this activity prior to submitting devices for testing or LexaMed is equipped to help with this.      

 

Contamination

Trained analysts inspect each device to determine the most difficult areas for disinfection such as lumens, hinges and matted surfaces.  Devices are then directly inoculated in these areas with a challenge organism and allowed to dry.

 

Recovery Efficiency Studies

Analytical test methods used to determine levels of challenge organism(s) remaining on devices following disinfection cannot always recover 100% of the soils present on a device due to the various materials of construction and configuration.  Prior to extraction a Recovery Efficiency Study is performed for each challenge organism to determine the percentage that can be recovered during extraction.  Using the results of this test, a recovery factor is calculated and then applied to all testing conducted. 

 

Neutralization Efficacy Studies

Prior to disinfection, a Neutralization Efficacy Study is performed for each challenge organism to verify the ability to effectively neutralize residual disinfectant and recover injured organisms without adversely affecting the viability of the challenge organism(s).

 

Disinfection

Inoculated devices are disinfected using either the manufacturer’s recommended disinfection process or a process developed as part of the validation. Using the manufacturer’s specified instructions, disinfection is performed using a manual process such as wiping, soaking, or a combination of these methods.  Disinfection may also be conducted using an automated process.  Following disinfection, the devices are extracted using the validated recovery method.

 

Extraction

Disinfected devices, a negative control device which was disinfected without contamination and a positive control which was contaminated but not disinfected are extracted using the method determined during the recovery efficiency study. Residual disinfectant will be neutralized using the method determined during the neutralization efficacy study.  Any residual challenge organism not removed during the disinfection process will be extracted from the device. 

Testing

Extracts from the test articles and controls are evaluated to determine if the disinfection process effectively reduced the challenge organism(s) to acceptable levels.  Extracts are tested to determine the number of residual microorganism(s) on disinfected devices compared to those on the positive control device. Log-reduction acceptance criteria is based on the category of disinfection:

Low-Level Disinfection

6-log reduction of Pseudomonas aeruginosa

6-log reduction of Staphylococcus aureus

6-log reduction of Escherichia coli

6-log reduction of a representative of the Klebsiella-Enterobacter group

Intermediate-Level Disinfection

6-log reduction of Pseudomonas aeruginosa

6-log reduction of Staphylococcus aureus

6-log reduction of Escherichia coli

6-log reduction of a representative of the Klebsiella-Enterobacter group

3-log reduction of Mycobacterium spp.

High-Level Disinfection

6-log reduction of Mycobacterium spp.

The final step is an evaluation to determine if the disinfection process effectively removed disinfectant residuals to a safe non-toxic level.  A disinfected device is subjected to an ISO Cytotoxicity Test to measure the level of any toxic residuals that may be remaining following the disinfection process.