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Sterility Testing by Direct Inoculation

STERILITY TESTING BY DIRECT INOCULATION FOR NON-FILTERABLE SAMPLES

Direct inoculation is a sterility testing procedure to assess the safety of pharmaceutical products.

Reliable sterility testing and the development or validation of product-specific methods are critical steps in the drug development process. Although international pharmacopeias recommend using standard membrane filtration for sterility testing, certain products are not filterable or deformable. These products are normally tested using direct inoculation – using a range of sterility testing media including soybean casein digest medium (TSB), and Fluid Thioglycollate medium (FTM standard and clear). In this method, the test sample is directly inoculated into the required media, ensuring that the amount of sample is below 10% of the total media volume.

Advantages of Direct Inoculation
Culture Media for Direct Inoculation
Soybean-Casein Digest Medium (Trypticase Soy Broth, TSB)
Fluid Thioglycollate Medium (FTM)
Clear Thioglycollate Medium
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ADVANTAGES OF DIRECT INOCULATION

In the direct inoculation (immersion) method, the test articles are inoculated directly into tubes or bottles containing an appropriate medium and incubated for 14 days. To comply with the different direct inoculation methods for sterility testing requirements, we offer a wide range of customized sterility testing media in various volumes sizes and bottles (from 9 mL tubes up to 750 mL) to fit your applications.

The direct inoculation method:

Provides a mode for sterility testing of materials that cannot be easily filtered.
Consumes less product volume during the conduct of the bacteriostasis and fungistasis (B&F) testing.

CULTURE MEDIA FOR DIRECT INOCULATION

In the direct inoculation method, the sample is directly inoculated into two types of media. One medium allows the growth of anaerobes, while the other medium supports the growth of aerobes. Fluid thioglycollate medium (FTM) is the commonly used medium for anaerobes, while tryptic soy broth (also called soybean casein digest medium) is more suitable for aerobes. The aerobic and anaerobic microorganisms are detected separately in the respective media at the end of the incubation period.

Soybean-Casein Digest Medium (Trypticase Soy Broth, TSB)

Soybean-Casein Digest medium is suitable for culturing fungi and aerobic bacteria. This medium is used for sterility testing by direct inoculation. It is also used as a pre-enrichment broth for nonsterile products.

产品编号	产品名称	说明
1.46432	TSB	tube capacity × filling volume 17 mL × 9 mL, closure type, blue screw cap with 2 loci, box of 100 tubes
1.46334	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 275 mL, bottle filling volume 90 mL, closure type, white screw cap for wide neck, box of 6 or 30 bottles
STBMTSB12	大豆酪蛋白消化肉汤	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, green screw cap with septum, pack of 12 bottles
STBMTSB12DP	大豆酪蛋白消化肉汤	bottle capacity 125 mL, bottle filling volume 100 mL , filling volume, closure type, green screw cap with septum, double packed of 12 bottles
1.46357	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 275 mL, bottle filling volume 100 mL, closure type, white screw cap for wide neck, box of 6 bottles
1.46335	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 250 mL, bottle filling volume 100 mL, closure type, red screw cap with 3 loci, box of 6 bottles
1.46317	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, blue crimp cap with septum, pack of 10 or 70 bottles
1.46458	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, blue screw cap with 3 loci, pack of 10 bottles
1.46342	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 1000 mL, bottle filling volume 750 mL, closure type, yellow screw cap with septum, box of 6 bottles
1.46379	胰蛋白胨大豆肉汤，即用型瓶装	bottle capacity 1000 mL, bottle filling volume 1000 mL, closure type, blue screw cap with 3 loci, box of 6 bottles

Fluid Thioglycollate Medium (FTM)

Fluid Thioglycollate medium is suitable for the detection of anaerobic and aerobic bacteria. This medium is used for sterility testing by direct inoculation as described in the USP, EP, and JP.

产品编号	产品名称	说明
1.46220	巯基乙酸盐培养基	tube capacity 17 mL, tube filling volume 9 mL, closure type, Red scew cap with 2 loci, pack of 100 tubes
1.46139	流体巯基乙酸盐培养基	tube capacity 17 mL, tube filling volume 10 mL, closure type, Red scew cap with 2 loci, pack of 100 tubes
STBMFTM12	流体巯基乙酸盐培养基	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, Red screw cap with septum and protector, pack of 12 bottles
STBMFTM12DP	硫乙醇酸盐流体培养基，双层包装	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, Red screw cap with septum and protector, double packed of 12 bottles
1.46387	流体巯基乙酸盐培养基	bottle capacity 1000 mL, bottle filling volume 750 mL, closure type, White screw cap with septum and protector, pack of 6 bottles

Clear Thioglycollate Medium

Clear Thioglycollate medium has the same growth promotion properties as the standard FTM and is compliant with the USP, EP, and JP. This alternative formulation brings extra visual clarity versus the FTM, which has slight turbidity or haze due to the presence of agar.

产品编号	产品名称	说明	价格
STBMCTM12	透明流体巯基乙酸盐培养基	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, Red screw cap with septum and protector, pack of 12 bottles
STBMCTM12DP	Clear Thioglycollate Medium	bottle capacity 125 mL, bottle filling volume 100 mL, closure type, Red screw cap with septum and protector, double packed of 12 bottles

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Discover our full sterility testing portfolio based on over 45 years of experience and expertise. Our large variety of devices and pumps, along with sterile culture media and rinsing fluids can help you to stay compliant, whether you use membrane filtration or direct inoculation methods. Reduce the sterility testing workload and focus on your critical lab activities thanks to our extended Steritest^® services portfolio. The experienced application and validation engineers will assist in method development and validation implementation within the QC microbiology laboratory. They will also provide basic and advanced technical training on sterility testing, in person or remotely.