Microbiology

Microbiology Testing

Microbial assays involve a variety of tests, from the determination of the numbers and types of organisms naturally present on a product to the assessment of controlled environments. With our comprehensive menu of microbiology services, WuXi AppTec Laboratory Testing Division Medical Device Platform provides testing across the product development lifecycle and beyond, from R&D and screening to in-process release, validations and finished product delivery.

blank

Bacterial Endotoxin (LAL)

Pyrogens are fever-producing materials that most often originate from Gram-negative bacterial cell walls, but can also originate as leachates from some chemicals and materials. Pyrogens from bacterial cell walls (the most commonly encountered type of pyrogen) are referred to as bacterial endotoxins and are readily detected by Limulus Amebocyte Lysate (LAL) testing systems. Kinetic Chromogenic
Quantitative assay for the detection of gram-negative bacterial endotoxin. The presence of the endotoxin causes a color change and the solution becomes yellow.
Kinetic Turbidimetric
Quantitative assay for the detection of gram-negative bacterial endotoxin. The presence of the endotoxin causes the lysate to gel and the solution to become cloudy or opaque.
Limulus Amebocyte Lysate (LAL) Test Validation (Inhibition/Enhancement)
Validation of the inhibition or enhancement properties of materials on the test system.
LAL Limit Test – Finished Product Testing
Quantitative determination of endotoxin level for finished devices or other materials.
 
LAL Liquid Test
Endotoxin testing of water system samples or other non-biological liquids.
 
 

Sterility Method Suitability (B/F)

The Sterility Method Suitability Test (B/F) is necessary to demonstrate that there are no substances produced by the test materials (in the specified volume of test medium) that would cause inhibition of bacterial or fungal growth in a sterility test (i.e., a false negative interpretation). Sterility Method Suitability (Bacteriostatis/Fungistasis)
Sample device or material in the sterility test medium is tested for growth inhibition using the current USP organisms for Soybean-Casein Digest Medium (SCDM) and Fluid Thioglycollate Medium (FTM). (Additional organisms available upon request.)
Sterility Method Suitability Test (B/F) – AAMI
Medical device in the sterility test medium is tested for growth inhibition via AAMI standard using Soybean-Casein Digest Medium (SCDM).

Product Sterility

Product sterility testing is typically performed in the validation of sterilization processes, and, in some cases, for monitoring sterilization cycles. Sterility tests involve total immersion, membrane filtration, or a rinse method. The number of samples tested, the growth medium used, and the incubation conditions are based on the particular standard involved – USP, AAMI/ISO or FDA/CFR. Sterility Immersion
This test is used in sterilization validations (e.g., radiation, EO), and to monitor sterilization loads. This test follows USP, AAMI, ANSI and ISO standards.
Sterility Membrane Filtration
This test is used in sterilization validations (e.g., radiation, EO), and to monitor sterilization loads. This test follows USP, AAMI, ANSI and ISO standards.
Pyronema Screening
This test is used to determine the presence of Pyronema in sterilized products.

Bioburden

Bioburden testing is an assessment of the numbers and types of microorganisms present on a product, and used for assessment of incoming materials, indication of manufacturing conditions, and support of sterilization validations. Aerobic Bioburden
Aerobic count
Fungal Bioburden
Mold and yeast count
Spore Bioburden
Aerobic spore count
Anaerobic Bioburden
Anaerobic count
Total Bioburden Panel Aerobe / Anaerobe / Spore / Fungi
Intended for items for which a full characterization of the bioburden is needed. Additional combined bioburden testing is available
Bioburden Recovery Efficiency – Repetitive Recovery Method
Devices with high naturally occurring bioburden are extracted multiple times to determine overall efficiency of the first extraction
Bioburden Recovery Efficiency – Spore Inoculation Method
Devices with low naturally occurring bioburden are inoculated with a known quantity of bacterial spores to determine overall efficiency of the extraction process

Biological Indicators

Biological indicators (BIs) are carriers, such as a paper strip, that are inoculated with a specified level of a particular organism (typically Bacillus species). BIs are used to validate and/or monitor certain sterilization Biological Indicator
Spore strips are transferred from their primary package to Soybean Casein Digest Medium (SCDM) and incubated for the recovery of the indicated organism. BI occurs through three different methods: direct transfer, within product, or self-contained in the product or packaging.

Inoculated Product

Inoculated products consist of actual devices or materials that have been inoculated with a specified level of a liquid biological indicator (BI) suspension or a BI carrier strategically placed within the device. Inoculated products are used to validate and / or monitor certain sterilization processes. USP Biological Indicator: Total Viable Spore Count
Before a new lot of BIs for sterilization load monitoring, the average population per unit should be independently confirmed per USP regulations. This may be conducted with suspension, composition of 4 BI carriers, or a composite per the manufacturer’s instructions.

Microbial Identification

The ability to identify the microbial strain present. Microbial Identification
Remove – gram stain, colony morphology, and gram stain and colony morphology
Gram Stain
Differential staining technique used to categorize microorganisms.
Colony Morphology
Description of an organism’s macroscopic (colony) appearance, including shape, color and texture
Gram Stain and Colony Morphology
Description of an organism’s macroscopic (colony) appearance, including shape, color and texture, plus differential staining to determine organism category.
Bacterial / Microbial Identification
Identification of a microbial isolate to at least the genus level.
Fungal / Microbial Identification
Identification of a microbial isolate to at least the genus level.

Microbiological Examination

Microbiological Examination Tests, as outlined in USP <61> and <62>, are designed to provide an estimate of the number of viable aerobic microorganisms, both bacteria and fungi, and/or to screen for specific target microbial species. Microbial Enumeration Tests – Suitability (USP <61>)
This is designed to demonstrate the USP <61> procedure used to test the product is suitable.
Microbial Enumeration Tests – Testing of Products (USP <61>)
Test is designed to determine total aerobic microbial count, and total yeast and mold count that can be recovered from the test material under the conditions and by the methods outlined in USP <61>.
Tests for Specified Microorganisms – Suitability (USP <62>)
This is designed to demonstrate the USP <62> procedure used to test the product is suitable.
Tests for Specified Microorganisms – Testing of Products (USP <62>)
Test is designed to demonstrate freedom of the test material from Bile-tolerant Gram-Negative Bacteria, Escherichia coli, Salmonella, Pseduomonas aeruginosa, Staphylococcus aureus, Clostridia and Candida albicans.
 

Growth Promotion

Prepared media must be tested prior to use to ensure it will support the growth of low levels of microorganisms. We offer this testing per USP requirements as well as customized per client request. Growth Promotion for Liquid Media (3 or 6 orgs per media per USP <71>)
Sterility Test Medium is tested for growth promotion using the current USP <71> organisms, for each media type SCD and/or FTM.
Growth Promotion for Solid / Liquid Media (5 orgs per USP <61>)
Growth Medium is tested for growth promotion using the current USP <61> organisms.
Growth Promotion per Organism
Growth Medium is tested for growth promotion using selected organisms in specified media.