Sterility testing is an important quality control step for many sterile pharmaceutical products, including injectable drugs, ophthalmic preparations, inhalation products, and other dosage forms intended to meet sterility requirements at release.
NJ Labs provides USP <71> sterility testing of pharmaceutical products using membrane filtration and direct inoculation techniques, supported by growth promotion testing (USP <71>) and method suitability testing (USP <71> bacteriostasis and fungistasis) to support method performance and result interpretation.
As an FDA- and DEA-registered facility, NJ Labs performs testing under validated microbiological procedures in controlled aseptic environments. Our services support routine quality control testing, method validation studies, and regulatory submission documentation.
USP <71> is the United States Pharmacopeia general chapter that describes standardized procedures for sterility testing of pharmaceutical products, biologics, and certain medical products.
It is harmonized with Ph. Eur. 2.6.1 and is recognized by regulatory authorities including the US FDA. The method is qualitative, and results are reported based on the absence or presence of microbial growth after a 14-day incubation period.
A compliant result indicates that no microbial growth was detected under the test conditions in the analyzed sample units. However, USP <71> sterility testing represents a sample-based evaluation and is one component of an overall sterility assurance strategy, which typically includes validated sterilization processes, aseptic manufacturing controls, and environmental monitoring programs.
USP <71> sterility testing requirements are commonly applied as part of regulatory expectations for sterile product release.
USP <71> testing supports:
NJ Labs provides USP <71> sterility testing services for a wide variety of sample types and pharmaceutical dosage forms, including:
USP <71> specifies the use of two culture media to support recovery of a broad range of microorganisms.
| Culture Medium | Target Organisms | Target Temperature | Duration | Pass Indicator |
|---|---|---|---|---|
| Fluid Thioglycollate Medium (FTM) | Aerobic and anaerobic bacteria (incl. Clostridium spp.) | 30–35°C | 14 days | No visible growth |
| Soybean-Casein Digest Medium (SCDM / TSB) | Aerobic bacteria, yeasts, and molds | 20–25°C | 14 days | No visible growth |
FTM supports recovery of aerobic and anaerobic bacteria, while SCDM is intended to support growth of fungi and aerobic microorganisms at lower incubation temperatures.
Growth promotion testing (GPT) is performed to evaluate whether each batch of culture media can support the growth of specified compendial microorganisms prior to use in USP <71> sterility testing. Since sterility testing is a negative test system, confirmation of media suitability is an important control to help reduce the risk of invalid results due to non-performing media. GPT is performed using low-level inoculation (≤100 CFU) of specified test organisms, followed by observation of growth under defined incubation conditions.
Method suitability testing is performed to evaluate whether the product may interfere with microbial recovery during USP <71> sterility testing. Some formulations containing antimicrobial activity or complex matrices may affect microbial growth in culture media. If inhibitory effects are observed, neutralization strategies or adjusted test conditions may be evaluated and incorporated into the test method. Method suitability is generally reassessed when there are changes in formulation, manufacturing process, or test conditions.
The following compendial microorganisms are used in USP <71> sterility testing, growth promotion testing (GPT), and method suitability testing to evaluate microbial recovery across bacteria, yeasts, and molds.
| Organism | ATCC Strain | Type | Testing Relevance |
|---|---|---|---|
| Staphylococcus aureus | ATCC 6538 | Gram-positive bacterium | Representative skin/environmental contaminant commonly associated with aseptic processing environments |
| Bacillus subtilis | ATCC 6633 | Spore-forming bacterium | Evaluates recovery of resistant spore-forming organisms |
| Pseudomonas aeruginosa | ATCC 9027 | Gram-negative bacterium | Representative waterborne and environmental contaminant |
| Clostridium sporogenes | ATCC 11437 | Anaerobic spore-forming bacterium | Confirms anaerobic growth conditions in Fluid Thioglycolate Medium (FTM) |
| Candida albicans | ATCC 10231 | Yeast | Representative fungal organism for sterility test system suitability |
| Aspergillus Niger | ATCC 16404 | Mold | Evaluates fungal recovery in Soybean-Casein Digest Medium (SCDM) |
USP <71> sterility testing is conducted in a controlled aseptic environment, typically Grade A (ISO Class 5) within a Grade B background or within an isolator system. Isolator systems are increasingly used to reduce the potential for environmental contamination and to improve process control during sterility testing.
| Parameter | Membrane Filtration | Direct Inoculation |
|---|---|---|
| Applicability | Aqueous, oily, or alcoholic filterable formulations | Ointments, suspensions, bulk solids, non-filterable products |
| Principle | Product filtered through ≤0.45 µm membrane; membrane transferred to media | Product added directly to media; volume ≤10% of total media volume |
| Sensitivity | Generally higher due to larger sample volume processed | Dependent on inoculated volume |
| Interference Control | Managed via rinsing steps | Managed via dilution or neutralization |
Method selection is based on product characteristics and confirmed through USP <71> method suitability testing.
| Outcome | Observation | Interpretation |
|---|---|---|
| Pass | No microbial growth observed | Test conditions compliant for analysed units |
| Fail | Microbial growth observed | Investigation required; may indicate contamination |
| Invalid Test | Confirmed procedural or environmental issue | Retesting may be considered based on investigation outcome |
Note: A passing result indicates compliance for the tested sample units but does not establish absolute sterility of the entire batch.
USP <71> sterility testing may be applicable to a broad range of sterile pharmaceutical products, biologics, and certain medical devices intended to meet sterility requirements at release. Applicability is generally determined based on product classification, route of administration, manufacturing process, and regulatory expectations within the target market.
The following categories represent common examples where USP <71> sterility testing of pharmaceutical products is typically performed as part of quality control or regulatory submission programs.
For medical devices, sterility evaluation may also be performed in accordance with ISO 11737-2, depending on regulatory pathway and product classification.
In addition, pharmaceutical water systems such as Water for Injection (WFI) are typically evaluated under USP <1231> and related microbiological methods rather than USP <71>.
Regulatory Note: The applicability of USP <71> sterility testing requirements is determined based on the intended product claim, manufacturing process validation, and regulatory expectations of the target market. Final test strategy is typically established as part of the overall sterility assurance program.
NJ Labs provides USP <71> sterility testing services for pharmaceutical products using membrane filtration and direct inoculation methods, supported by growth promotion testing and method suitability evaluation.
To initiate testing, please provide product details, dosage form, and applicable regulatory requirements for review.
USP <71> sterility testing is a compendial microbiological test used to determine the presence or absence of viable microorganisms in pharmaceutical products. The method involves incubating samples in specified culture media for 14 days under defined conditions, with results reported as a qualitative pass or fail based on microbial growth.