Culture Media FAQ

Refer to the Quality Control section of the Product Insert for each item. Each insert provides a list of organisms used for quality control testing at Anaerobe Systems, including the ATCC number for the appropriate strain. Not all organisms are required for user quality control testing. Please refer to the Centers for Medicare & Medicaid Services (CMS) requirements for Clinical Laboratory Improvement Amendments (CLIA) or your lab implemented Individual Quality Control Plan (IQCP) requirements for more information. View our Product Inserts

We recommend that customers record the number of items per lot that exhibit any of the characteristics listed below and report to Anaerobe Systems immediately. A small portion of contamination or product defects are normal, however if the issue is greater than 4% of the total lot received please report to Anaerobe Systems. Issues can be reported to customer service at 1-800-443-3108 or at If possible, please email photos to aid in the investigation process. Visually inspect each item in the lot for obvious problems such as:

  • damaged or cracked plates;
  • agar detached from plates;
  • signs of frozen or melted agar;
  • insufficient agar in the plates or tubes;
  • hemolysis of blood containing media;
  • change in the expected color of the media (possible pH problem or browning due to oxidation);
  • excessive bubbles or pitting;
  • excessive moisture or dehydration; and
  • obvious contamination

Our culture media can be opened and exposed to oxygen for up to 30 minutes. We recommend placing the culture media inside an anaerobic environment, such as an anaerobic chamber or jar, immediately after opening or inoculating the media. Oxygen can react with the culture media forming byproducts toxic to the anaerobic organisms.

Prereduced anaerobically sterilized (PRAS) media describes a medium whose oxygen has been removed before heat sterilization. The medium is then autoclaved, dispensed, and packaged under oxygen-free conditions. This method prevents the reaction of reducing agents present in the medium with oxygen, which would lead to the formation of products that are harmful to, or would limit the growth of, anaerobes in that medium. PRAS media when packaged oxygen-free in aluminum packets can be stored at room temperature. PRAS media requires no prereduction step by the end user and is ready for use as soon as the package is opened. Learn more about PRAS media here.

Based off the Clinical and Laboratory Standards Institute (CLSI) document M56-A: Principles and Procedures for Detection of Anaerobes in Clinical Specimens; Approved Guideline, clinical specimens should be transported to the laboratory using an oxygen-free, prereduced anaerobically sterilized (PRAS) transport tube or vial. Our anaerobic transport systems contain oxygen-free gas and a modified Cary-Blair transport medium containing an anerobic indicator. The media should appear transparent and colorless before use. If a pink/purple coloration is observed at the top of the media before use the vial should not be used. This coloration indicates that the anaerobic conditions of the media have been compromised and could affect performance. The anaerobic transport tube has a stopper with a rubber septum and a plastic screw cap (AS-914 and AS-911 only) or a wide mouth short vial with a phenolic cap (AS-915 and AS-919 only). Specimen aspirates are injected into the transport tube through the rubber septum that has been decontaminated with alcohol. Swabs and small tissue biopsy specimens may be inserted into the transport media by removing the cap. Larger tissue specimens can be placed on the surface of the semi-solid medium in the wide mouth tube (AS-915 and AS-919). Submerging the tissue into the gel is not necessary, unless preferred by the processing laboratory. Tubes are recapped and rapidly sent to the laboratory. The use of swabs is discouraged; however, if used due to limited quantity of specimen, it is best to use those made of synthetic fibers. Do not use cotton wool swabs that may contain inhibitory fatty acids.