PBL Logo - click here to return to homepage spacer


Microbial limits testing for pharmaceutical products is an important part of gmp microbiology. These procedures are performed to determine whether a product complies with compendial specifications for microbial quality, and consists of two parts. The quantitative phase, Microbial Enumeration, gives the total number of aerobic organisms as well as a total yeast and mold count on a product. The qualitative phase is known as the Test for Specified Microorganisms. This test is designed to determine the presence or absence of specific objectionable organisms in a product.

Prior to performing MLT testing on a product, the method must be validated to ensure that the product has no microbial inhibitory properties which could produce false negatives. This validation testing is known as the MLT Method Suitability Test.

The relevant standards for the Microbial Limits Test have been harmonized for the US, European, British, and Japanese markets. The relevant standards are USP <61> and <62>, EP Chapter 2.6.12 and 2.6.13, BP Chapter B1 and B2, and JP XV 1st Supplement.

Visit our Learning Center to discover more about the Microbial Limits Tests.

Available Pharmaceutical Microbial Limits Testing Services

  • MLT Method Suitability Test
  • Microbial Enumeration (Total Aerobic Microbial Count and Total Combined Yeasts and Mold Count)
  • Screening Test for Specified Microorganisms:
    • P. aeruginosa
    • E. coli
    • S. aureus
    • Salmonella
    • Bile tolerant gram negative bacteria
    • C. albicans
    • Clostridium
Intertek Logo PBL is FDA registered and ISO 9001:2008 and ISO 13485:2003 certified by Intertek. AAALAC Logo Our animal science operations are accredited by AAALAC.

Request a quote Send an email