31 March, 2023

A Complete Guide to Bioburden Testing

How Does Bioburden Work?

Bioburden signifies the number of bacteria still present in an area yet to be sanitized. Although bioburden can be found on any surface, testing for it is necessary for medications, medical devices, and other regulated items to prevent the loss of life.

Before sterilizing a product or material, it is recommended to conduct bioburden testing to determine the total number and types of viable microorganisms present. It’s an important step in choosing the right way to sterilize, finish, and distribute materials and products.

The collection of samples or methods for recovering microorganisms from products and medical devices is an essential step in bioburden testing. The pharmaceutical, medical device microbiology testing and cosmetics industries all make extensive use of bioburden testing.

What Is The Purpose Of Bioburden Testing?

The bioburden test is used to identify manufacturing process issues that may result in inadequate sterilization. Numerous pharmaceutical and medical products undergo bioburden testing for quality control. This testing is required for many new drugs and medical products before they can be used or ingested to determine the total number of microorganisms.

Before sterilizing any materials or products, the purpose of bioburden testing is to isolate and count all viable microorganisms. Laboratories all around the world leverage these testing methods for a variety of purposes, including:

  1. Knowing how to sterilize the water and raw materials used to make various products is helpful.
  2. It also helps figure out how many viable microorganisms are in medical devices before and after they are used.
  3. Bioburden testing makes it easier to keep laboratory standards in line with the rules or protocols that are followed.

Application of Bioburden Testing

The estimation of microorganisms in samples such as containers, medical devices, water, in-process samples, and final bulk products before sterilization, product contact surfaces, or materials that necessitate frequent bioload assessments is known as bioburden testing. Another popular procedure used to verify sterilizing techniques is bioburden testing. Testing for bioburden is frequently conducted in the following contexts:

  • Laboratories for Microbiology

These laboratories deal with microorganisms constantly but also need a sterile area to work in. As a result, the total aerobic microbial count is frequently determined by bioburden testing.

  • Companies That Produce Medical Devices And Products

Due to their constant contact with immunocompromised individuals, these businesses must produce materials and devices with very little, if any, bioload. Therefore, pre-sterilization bioburden testing of these products is preferred and recommended. Validating the method of sterilization is crucial.

  • Industries of Pharmaceuticals

In the pharmaceutical industry, the final bulk of oral drugs before sterilization, the water used to produce drugs, containers, and surfaces frequently serve as samples for bioburden testing.

  • Industries of Cosmetics

Bioburden testing is performed on the raw materials for cosmetics and bulk products before sterilization. Equipment used to make those cosmetics is also subjected to bioburden testing.

Why Does Bioburden Testing Take So Long?

Both sterile and nonsterile manufacturing processes require the determination of bioburden. Sterile products, like injectables or blood agar plates, are required. Certain thresholds must not be exceeded when it comes to non-sterile pharmaceuticals, such as conventional tablets and lotions for the skin. The product, its intended use, and the microorganisms in question all influence these limits. According to the United States Pharmacopeia (USP) Chapter 61, quantitative microbial examination of non-sterile products can be conducted. It lists the Gram-positive and Gram-negative bacteria, yeasts, and molds that will be used for method and culture validation. However, because these do not always reflect the situation on-site, the regulatory body frequently considers it advantageous to search for and validate against in-house strains that are more likely to be found on the product.

A Method for Expediting Bioburden Testing

When the compendial filtration test is being carried out, it is possible to add a simultaneous rapid test that uses the same sample to produce much earlier results while still allowing the compendial test to go on. A company has implemented this by combining the processes of two different rapid and compendial bioburden testing methods. It is the complementary method filtration system. Its pump moves the sample through a funnel with a filter membrane to remove any growth inhibitors and capture the microorganisms. After that, the membrane is moved without touching a media plate, where it is incubated until colonies can be seen and counted.

Bioburden Testing vs. other Testing Methods

Endotoxin testing identifies the bacterial endotoxin, a phospholipid present in the gram-negative bacteria’s outer membrane. Bioburden, on the other hand, includes counting bacteria and fungi in addition to endotoxin.

Bioburden testing determines the total quantity of viable (alive) microorganisms. Endotoxin testing, on the other hand, can identify and quantify non-viable bacteria because endotoxin is released by dead gram-negative bacteria.

Endotoxin is used in sterile, nonpyrogenic devices or equipment that typically come into contact with cerebrospinal, lymphatic, or cardiovascular fluids. Bioburden testing is also used to monitor raw materials, packaging, and the environment, as well as to validate the sterilization method.

Bioburden testing is a quantitative method that is carried out in non-sterile, pre-sterile, unfiltered and filtered samples. The microbial limit test is a comprehensive and proven method to measure the presence of contaminants in non-sterile substances.

Time Saved When There Is a Problem

What if the bioburden test results are higher than the limit? A strategy for both corrective and preventive action would be required to address the issue. The production line and deliveries to the market may halt during this time, which can take some time. Losing a day costs money. The identification of the cultured material during the ongoing compendial bioburden test can assist in determining the contamination’s underlying cause. However, rapid bioburden testing can provide an early indication that a problem exists, allowing investigators more time to gather initial data and manage resources, thereby expediting the investigation. When the result falls within the limit of the bioburden test, this adds to the benefits of earlier product release and lower storage costs.


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