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Microbial Limits Test
The microbial limit (contamination) test is used to test the microbiological content of pharmaceutical products which are not designed to be sterile, or raw materials used in the production of other products.
The EP and USP Microbial Limit Test is performed at ILS and is used to estimate the total number of viable micro-organisms present and for the absence of specific pathogens in pharmaceutical articles of all kinds.
The principle of the Microbial Limit Test is that each viable microbial cell present in a sample, will, when mixed with an agar medium, and after incubation, form a visible separate colony.
The enumeration of these colony-forming units (cfu), when taking into account sample preparation will give an estimate of the microbial population of the product under the specified incubation conditions.
Or that a range of dilutions of the sample, in a specified number of tubes containing a suitable medium and under specified incubation conditions, will give an estimate of the microbial population of the product using most probable number tables.
Or that filtering liquid samples, or dilutions of solid samples, through a membrane filter will retain any microbial cells on the filter and that each viable microbial cell present on the filter will, after incubation, form a visible separate colony when the filter is applied to the surface of an agar plate.
The enumeration of these colony forming units (cfu), when taking into account sample preparation, will give an estimate of the microbial population of the product under specified incubation conditions.
That non-selective enrichment, selective enrichment, selective plating and confirmatory testing will allow specific micro-organisms, which may be present in the sample, to be detected.
The presence of micro-organisms within purified water can also be assessed at ILS by performing a Total Viable Count using membrane filtration.
Harmonisation of Microbial Limit Test
Testing for microbial contamination is a part of a due diligence protocol that is designed to ensure safety of the pharmaceutical, healthcare or cosmetic cosmetics that you produce. Different regions of the world conduct Microbial Limits testing to their own (USP/ EP/ BP/ JP) regulations. These methods do not always match and this can cause confusion in the international marketing of pharmaceutical products. To overcome this, the USP and EP Microbial Limits test are being harmonised during 2009.
The test in the current version of the USP is divided into two chapters.
Chapter 61: Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests
Chapter 62 Microbiological Examination of Non-sterile Products: Tests for Specified Organisms.
These chapters will officially become effective on May 1, 2009. The EP version is already active.
The table below is a summary of the harmonised microbial limits test with the corresponding chapters in the USP and EP:
|USP61||EP/BP Chapter 2.6.12|
|Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests||Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests|
|Microbial Enumeration Tests||Microbial Enumeration Tests|
|Total Aerobic Count||Total Aerobic Count|
|Yeast and Mould Count||Total Fungal Count|
|USP 62||EP/BP Chapter 2.6.13|
|Tests for Specified Organisms||Tests for Specified Organisms|
|Bile Tolerant Gram Negative Bacteria (Added)||Enterobacteriaceae and certain other gram negative bacteria|
|Escherichia coli||Escherichia coli|
|Salmonella spp||Salmonella spp|
|Pseudomonas aeruginosa||Pseudomonas aeruginosa|
|Staphylococcus aureus||Staphylococcus aureus|
|Clostridia spp (Added)||Clostridia spp|
|Candida albicans (Added)|
USP 61 the need to undertake verification of enumeration.
Also, information on sample preparation for different matrices is added and on the neutralisation or removal of antimicrobial activity.
A negative control has been added to verify the media.
In USP 62 specific requirements for the growth and recovery of specified test organisms are stated and more species are added.
The confirmation of a doubtful result by retesting using 25 grams specimen of product is abolished.
Contact ILS - For further information and prices on microbial limit testing