Microbiological Detection of Compressed Air in Pharmaceutical Enterprises

In pharmaceutical companies, the microbiological testing of compressed air is a key link to ensure the cleanliness of the pharmaceutical production environment and prevent cross-contamination. The testing methods, standards, frequency and operating points are as follows:

1. microbial detection methods

1. sampling method
   • method of sampling for floating bacteria: Use a buoyant bacteria sampler (such as an impact sampler) to impact and intercept the microorganisms in the compressed air on the surface of the culture medium through high-speed airflow, and count the number of colonies after culture.
   • liquid impact method: The compressed air is passed through the sampling device equipped with liquid medium, and the microorganisms are captured and cultured to observe the turbidity and judge whether it is polluted. Although this method cannot be quantified, it is easy to operate and suitable for rapid screening.
   • plate direct blowing method: Expose the medium plate to the compressed air flow, but be careful to avoid external air interference, otherwise the result may be high.
2. culture and counting
   • after sampling, the medium should be cultured at a suitable temperature (e. g. 30-37 ℃) for 3-7 days, and the number of colony forming units (CFU) should be observed and recorded.

2. microbiological testing standards

1. general Criteria
   • GMP Requirements: Compressed air entering the sterile zone must reach the microbial limit level of Class A laminar air, I .e. ≤1 CFU/m³.
   • ISO 8573-7: The test method for the contamination of active microorganisms in compressed air shall be specified, and the floating bacteria shall be ≤ 10 CFU/m & sup3;(corresponding to the cleanliness level of the monitoring point).
   • Industry Practice: Some pharmaceutical companies adopt more stringent standards, such ≤0.03 CFU/ft³(about 1 CFU/m & sup3;) to ensure a highly clean production environment.
2. Key Indicators
   • number of floating bacteria: It directly reflects the degree of microbial contamination in the air and needs to be monitored and recorded regularly.
   • Other Pollutants: It is necessary to detect moisture, oil, particulate matter, etc. simultaneously to avoid microbial breeding (such as high moisture content can easily lead to bacterial reproduction).

3. detection frequency and period

1. newly installed system: The initial validation period is 3 months confirm system stability.
2. mature system: The detection period can be extended 6 months to 1 year however, it needs to be adjusted according to the risk of production environment.
3. Special circumstances:
   • when the microbial content exceeds the standard, it is necessary to immediately check the pollution source (such as filter failure, pipeline corrosion) and take improvement measures.
   • Production key processes (such as aseptic filling) need to increase the detection frequency to ensure real-time monitoring.

4. operation points and precautions

1. preparation before sampling
   • ensure that the sampler and culture medium are sterile to avoid cross-contamination.
   • The sampling points shall cover critical areas of the compressed air system (e. g. compressor outlet, point of use).
2. Sampling process control
   • adjust the compressed air pressure to a stable value (e. g. 0.3 MPa) to avoid airflow fluctuations affecting the results.
   • The sampling time should be standardized (e. g. 10 minutes) to ensure data comparability.
3. Results Interpretation and Improvement
   • combined with the characteristics of the production environment (such as humidity, temperature) comprehensive judgment of microbial contamination risk.
   • High values may indicate problems such as filter failure, pipeline leakage, etc., requiring timely repair or replacement.

5. testing instruments and tools

1. floating bacteria sampler: Used to quantitatively capture microorganisms in the air, such as impact sampler.
2. Incubator: Provide suitable temperature and humidity to promote microbial growth.
3. Draeger detection tube quantitative detection of water vapor, oil and other pollutants in compressed air, auxiliary microbial detection.
4. high pressure diffuser: Used in conjunction with a dust particle counter to detect particulate matter in compressed air.