Putting microbiology media under the microscope

Andrew Ramage, microbiology product specialist, Cherwell Laboratories, puts outsourcing of microbiological growth media under the microscope revealing the benefits and what makes an ideal media manufacturer.

Anyone who manages or works in a microbiology laboratory will know how time consuming and resource hungry making microbiological growth media is. Speaking from experience, during the early days of my career as a microbiologist working in a small food testing lab, the making of media and the subsequent growth promotion testing took up a significant portion of the day. Valuable time when there were hundreds of samples to test and report.

The autoclaves had to be cleaned regularly, as well as maintained and calibrated. Any problems with the autoclave would bring testing to a grinding halt, especially if you did not have an adequate stock of media. The same could be said if the media failed growth promotion and pH testing.

If all the above seems familiar, maybe it is time to consider outsourcing your microbiological growth media?

Short-term versus long-term savings

You may think that making media in-house is a lot cheaper than purchasing media externally. However, that depends on how you do your calculations. At the most basic level, you may only be looking at the cost of the media dehydrate, supplements, water and containers (petri dishes and bottles).

Compared to pre-prepared media, that is true. To get a more accurate reflection of the cost have you factored in the cost of employing and training staff to make the media? The cost of running the autoclaves daily? Equipment calibration and maintenance; balances and pH meters as well as autoclaves? The cost of validating autoclave cycles? Maintaining a clean environment to manufacture media to avoid cross contamination with other media? Investigating media quality issues? Not as cheap now, is it?

Outsourcing of microbiological growth media removes all the above from your workload. A high-quality media manufacturer will do all that for you, freeing up your valuable time and resources. The media manufacturer is also able to buy raw materials in bulk, which reduces the unit cost compared to the relatively small usage of an individual laboratory.

Ensuring quality

As a customer, you will expect the highest quality product. To do so internally is a drain on resources. What makes a good media manufacturer and what does a media manufacturer do to ensure quality?

Starting at the top level, the manufacturer should have a defined, robust quality system in place, in all areas of the company. This will encompass sales, accounts, quality, production, maintenance and warehouse. You should expect a minimum of ISO 9001 accreditation.

The manufacturer will make media in dedicated facilities of cleanroom grade to reduce the chances of contamination and cross-contamination. All the equipment will be calibrated regularly with a planned preventative maintenance regime to ensure reliable operation. The water used, whether WFI (water for injection) or demineralised, will be of the highest quality, so should have a low microbial count and conductivity.

The raw materials will be sourced from trusted suppliers who have been vetted by the manufacturer, both for quality and reliability of delivery. Such materials will include media dehydrates, supplementary additives, petri dishes, glass containers, even the labels and packaging. Combined, the media will be manufactured via a validated, consistent, fully documented process.

After manufacture comes the quality control checks and inspection. The media manufacturing process is not perfect, so it is vital you can have confidence that the media performs to your expectations. There should be no particulates or air bubbles in agar plates that may give false results, and no excess moisture on the agar surfaces before packing. A good manufacturer will have a thorough inspection process of the media before packing, employing a well-trained team able to spot the smallest imperfections.

The quality control testing in the laboratory should conform to the prescribed methods depending on the regulatory requirements that medium will be used in. These will include numerous ISO standards, or GMP regulations as set out in the European Pharmacopoeia, or US Pharmacopeia. Testing of the product does not end at release, the manufacturer should be able to guarantee performance throughout, if not beyond, the stated shelf life of the product.

Bespoke solutions

Does your media supplier only sell catalogue items, or can they be flexible to meet your needs? To ensure minimal disruption and smooth validation of outsourced media you may want a product in a packaging format that is close to what you are making in-house. There is enormous variation in the types of products being tested, off-the-shelf products may not meet your exact requirements (which is why you are probably making media/buffers/diluents in-house). An exact or close match will make validation far easier. You should be able to talk to the supplier or manufacturer to have media that is manufactured to your specifications at a sensible price.

Delivery and reliability

The one thing a media manufacturer cannot replicate is being able to make media immediately there and then. Even I admit that is one of the great attractions of making media in-house. The manufacturer however should be able to guarantee a reasonable lead time on your order. The product that arrives should also have the maximum possible shelf life remaining. There is nothing more annoying than ordering an item with a six-month shelf life, only to find it has two to three months remaining when you receive it.

Part of that reliability should be having a proven track record at processing orders efficiently. If you know of other customers of that manufacturer, it will be good to get their opinion on the service they supply.

Open and honest

The final point to make is that your manufacturer should be open and honest. It may be a regulatory expectation you audit your suppliers on a regular basis. Your supplier should be ready and willing to host customer audits with the appropriate personnel on hand to answer your questions. They should also take on board any issues you may find.

A good manufacturer will always see an audit as an opportunity to make improvements, not as a box ticking exercise.