A rapid and simple sterility test method based on solid culture medium containing blood

Area of Science:

• Microbiology
• Pharmaceutical Science
• Analytical Chemistry

Background:

• Current sterility testing for biological products typically requires 14 days.
• Existing methods face challenges in sensitivity and speed, particularly with certain sample matrices.

Purpose of the Study:

• To evaluate the efficacy of a solid medium, specifically Schaedler blood agar (SBA), for improving sterility testing.
• To compare the performance of SBA against compendial methods for membrane filtration (MF) and direct inoculation (DI) sterility tests.

Main Methods:

• Microorganisms were tested using compendial MF sterility tests (fluid thioglycolate medium and tryptic soy broth) and on SBA.
• Representative microorganisms were inoculated at various concentrations (0.1-100 CFU) in a sample matrix.
• Solid medium was also assessed for direct inoculation (DI) sterility testing.

Main Results:

• SBA demonstrated significantly higher sensitivity and speed in detecting microorganisms compared to compendial methods (p < 0.05).
• All tested microorganisms were detected by SBA within 7 days, and within 5 days using DI.
• Optimizing incubation conditions for SBA identified limitations for detecting certain molds at elevated temperatures.

Conclusions:

• Schaedler blood agar (SBA) offers a faster and more sensitive approach to sterility testing for biological products.
• The SBA method can potentially reduce sterility test completion time to 7 days.
• Further optimization of incubation conditions may be needed for comprehensive mold and yeast detection.