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Microbial Ingress testing is the evaluation of the ability of a medical device to resist or inhibit the transfer of infectious microorganisms under repeated simulated use conditions. Many medical devices have features that could potentially allow microorganisms a point of entry directly into a patient or into sterile fluids during the course of clinical or home use, increasing the patient's risk of infection. This is especially true with repeated use, product misuse, or in the event of product failure.
Additionally, because surfaces can become contaminated during the course of normal device use, effective disinfection of devices and injection sites is critical to assure that patient safety is maintained. Microbial ingress testing can be used to evaluate these risks and to help manufacturers design effective products and/or recommend appropriate disinfection practices.
Microbial Ingress Background
The FDA has recommended the use of microbial ingress tests and has provided guidance concerning the practice of microbial ingress testing as part of the premarket approval [510(k)] process for Intravascular Administration Sets.2 In Section 8 “Microbial Ingress Testing” the guidance includes the following:
“We recommend that you provide results from a simulated use test for microbial ingress in your device. Testing should simulate the use of the device in a clinical setting, i.e., the number of microbial challenges in the study should approximate the number of user interactions with the access site that would be expected clinically. The testing should demonstrate that the disinfection procedures you use are effective. We recommend that you provide an analysis of the study results and a summary of the results and conclusions.”
Additionally, the FDA recommends that manufacturers provide a detailed study protocol that fully describes the study procedures used, including the preparation, quantities and types of challenge organisms, the contamination or inoculation methods and sites, the sample size, the environmental conditions, the positive and negative controls used, the validation methods and the rationales used for these choices. Typically two gram negative and two gram positive organisms are chosen to demonstrate the aboility to a medical device to prevent ingress of microorganisms.
Flexibility of Microbial ingress testing
The requirements for microbial ingress testing can be adapted for many different types of medical devices. The specific procedures and test conditions of the testing protocol are outlined for each individual case prior to initiating evaluation in order to meet the needs of the sponsor and best mimic the use of the actual device.
Worst-case simulated use conditions are used throughout the testing to help ensure definitive results. For example, devices are thoroughly contaminated, conditions optimal for maximum microorganism transfer are employed, and repeated usage cycles or repeated insertions are completed over an extended period of time.
Completion of microbial ingress testing will demonstrate the ability of the test device to prevent the transmission of microbial contamination when the agreed upon test procedures are followed.
As with any test method that simulates actual use, it is impossible to take all “real life” factors into account, and the test results will have limitations due to the assumptions used for the testing protocol. Microchem will work with the sponsor to identify appropriate procedures and test conditions for testing protocols in order to best replicate use during actual patient procedures within the imposed limits of time, cost, and ability.
Microbial ingress tests for Medical devices
The medical devices listed below are the some of the most common devices requiring microbial ingress testing. If you have questions about the methods for evaluating the devices listed below, contact the lab to speak with a scientist.
Since 1988 Microchem Laboratory has served industry needs as an EPA and FDA GLP-compliant testing organization with a wide array of product and customer tailored testing services for environmental surface disinfectants, high-level disinfectants, sanitizers, medical devices, antimicrobial surfaces, personal care products, and antimicrobial devices. Our skilled, highly experienced microbiologists and chemists are ready to collaborate with you to evaluate the performance of your antimicrobial devices with regards to microbial ingress. Microchem can help speed your project to completion.
Our microbial ingress studies are conducted following the guidance provided by the FDA1 in accordance with Good Laboratory Practice Standards (GLPs) stipulated by U.S. FDA 21 CFR 58. In addition studies are conducted in accordance with Microchem Laboratory’s Quality Management System and undergo a full quality assurance review. All studies by Microchem Laboratories are conducted in accordance with general terms and conditions as posted on www.MicrochemLab.com/terms.
- Photo Source: Stretchable Electronics. licensed for sharing under the under the Creative Commons Attribution 2.0 Generic license, as described in https://en.wikipedia.org/wiki/Bio-MEMS
- Guidance for Industry and FDA Staff: Intravascular Administration Sets Premarket Notification Submissions [510(k)], U.S. Department of Health and Human Services Food and Drug Administration, 2008, Rockville, MD. http://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm070850.pdf