Bacterial Endotoxin vs. Microbiology Testing
What is an endotoxin?
The “endo” in endotoxin refers to something that is within. The “toxin” component of endotoxin relates to something poisonous. Endotoxins can be deadly to humans and come from the cell walls of gram-negative bacteria. The endotoxins themselves are molecules with fat components (lipids) and complex sugar components (also known as polysaccharides). The fat and sugar components of endotoxins are why endotoxins are also known in scientific literature as lipopolysaccharides (LPS). Endotoxins are also considered pyrogens because they trigger the innate immune system and produce fever when released within the human body.
What is microbiology?
Microbiology can be broken down into the Greek and Latin roots of “micro,” “bio,” “ology.” The “micro” stands for small, the “bio” stands for biology, and the “ology” stands for “the study of.” Microbiology can also be defined by microbial, which refers to microorganisms. Suppose we put all of those Geek and Latin roots in combination with the definition of microbial. In that case, we understand that microbiology is the study of microorganisms, where microorganisms are small living components of the broad field of biology.
How do endotoxins and microbiology relate?
Microbiology has to do with identifying the species and genus of different microbes in a sample. Microbiology quantifies the number of microbes in a sample using colony-forming units (CFUs). In contrast, endotoxins are specific to gram-negative bacteria. Endotoxins are a harmful component of gram-negative bacteria, not the gram-negative bacteria itself. Microbiology can identify a particular type of gram-negative bacteria. However, endotoxin levels wouldn’t show up in regulatory microbiology testing.
What are the differences between bacterial endotoxin testing and microbiology testing?
Bacterial endotoxin testing measures the presence and quantity of endotoxins in a particular sample. In contrast, microbiology testing identifies the presence and the type of microbes in a manufacturing environment, medical product, or medical device. Specific regulatory testing for microbiology may include assays such as microbial enumeration testing, particulate analysis, yeast analysis, antifungal activity assessment, growth promotion testing, microbial limits testing, zone of inhibition testing, water analysis, bacteriostasis/fungistasis testing, bacteria identification, yeast identification, fungi identification, gram-negative staining, product inoculations, biological indicator tests, and BI incubation time reduction studies.
USP 61 and USP 62 govern microbiology testing. In contrast, bacterial endotoxin testing uses the methodologies outlined in USP 85. Note that traditional microbiology testing will not identify the presence of endotoxins in a sample or the level of bacterial endotoxin contamination present.
Why are both bacterial endotoxin testing and microbiology testing important?
Bacterial endotoxin testing is an important quality control step that detects the level of endotoxin contamination of a product at any stage, from initial product manufacture to final distribution. As microorganisms exist on every surface (including our body), bacterial endotoxins can be accidentally introduced during the manufacturing or packaging process in many ways. Some of the most common examples are contamination through the raw materials used, technicians, tubing/piping used to transfer product between development stages in a process, or the manufacturing environment itself. With such abundant sources of contamination, regular endotoxin testing supports the long-term control of manufacturing sites. Bacterial endotoxin testing is primarily for medical products or devices that will be inserted into the human body. Suppose bacterial endotoxins exist on the surface of a medical device or product or are present within an injectable product. In that case, the innate immune system of the patient exposed will be activated, causing fever, chills, and potentially death.
Microbiological testing is imperative for preventing product-induced infections and mitigating contamination risk in manufacturing environments, especially aseptic manufacturing environments. Aseptic manufacturing environments rely heavily on microbiological testing because aseptic processing requires excluding microorganisms from the manufacturing methods. Thus, microorganisms must be prevented from entering open containers or product materials during aseptic processing. As a result, microbial tests are used to monitor clean rooms and facilities that manufacture products using aseptic processing.
Summary
Overall, bacterial endotoxin and microbiology testing are imperative for regulatory approval of a medical device or product. These tests ensure that medical devices and products are free of toxins so that patients will not be at risk of pyrogenesis or infection following device exposure or product implantation. Ensure you choose a contract testing organization that can support you with appropriate microbiology and bacterial endotoxin testing for your unique medical device or product needs.
Ethide Labs is a contract testing organization that specializes in Bacterial Endotoxin Testing and Microbiology Testing. Ethide Labs also offers Bioburden Testing, Environmental Monitoring, Sterilization Validations,EO Residual Testing, Package Integrity Testing & Cytotoxicity Testing services for medical device companies and allied industries. Ethide is an ISO 13485 certified facility.
References
Galanos C. and Freudenberg M. A. Bacterial endotoxins: biological properties and mechanisms of action. Mediators of Inflammation. 1993; 2(7): S11–S16.
Nalbantsoya A. et al. Determination of in vivo toxicity and in vitro cytotoxicity of lipopolysaccharide isolated from Salmonella Enteritidis and its potential use for production of polyclonal antibody. Food and Agricultural Immunology. 2011.
Kessel R.W.I. et al. Endotoxin Cytotoxicity: Role of Cell-Associated Antibody. Experimental Biology And Medicine. 1966.
United States Pharmacopeial Convention. <61> Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests. Rockville, MD, USA. 2021. (USPC <61>).
United States Pharmacopeial Convention. <62> Microbiological Examination Of Nonsterile Products: Tests For Specified Microorganisms. Rockville, MD, USA. 2021. (USP <62>).
