How can I get a product that meets quality requirements?
Production and Quality Control of Medium Plate
The previous chapter introduced the quality requirements of the finished pre-loaded culture medium plate, so how can we get the finished pre-loaded culture medium plate that meets the expected quality requirements?
Let's first understand the simplified culture plate production process.
1
Preparation: When preparing the medium, accurately weigh the dehydrated medium that meets the requirements or prepare it according to the individual formula components. After the dehydrated medium or the individual formula components are completely dissolved, the bandwidth evaluation, PH value adjustment, and then temperature sterilization are carried out. The weight of each weighing substance and the amount of water used should be recorded.
2
Sterilization: After the preparation of the medium is completed, a verified sterilization procedure is selected, and it is immediately heated to the sterilization temperature for sterilization. After sterilization, it must be quickly cooled to the sub-packaging temperature. During the process, the temperature is very sensitive to the quality of the medium, so a comprehensive sterilization procedure verification is carried out according to the characteristics of the sterilization medium to ensure the normal heat distribution under a certain loading method.
3
Sub-packing: Sub-packing the sterilized and cooled culture medium into sterile empty dishes. Bubbles should be avoided in this process, the loading is uniform and stable, and the surface of the solid culture medium should not produce cracks or ripples or damage. After sub-packing, the cooling process should be protected by laminar flow and must not contaminate microorganisms.
4
Packaging: Packed petri dishes should be packaged in a timely manner. The media used for environmental monitoring should be specially protected and double-layer packaging is required. If it is a petri plate used for environmental monitoring in the A-level area, three-layer aseptic packaging is recommended.
5
End point sterilization: sterilize the packaged culture medium plate to ensure its sterility. Especially for the culture medium plate used for environmental monitoring, "Chinese Pharmacopoeia (2015 Edition) " 9203 clearly stipulates that "the culture medium used for environmental monitoring must be specially protected, preferably double-packed and end point sterilization".
6
Inspection and release:mediumAfter the production of flat dishes, each batch must be sampled and inspected before use. Inspection items include appearance, loading, pH value, sterility, and microbial growth promotion tests to ensure that the culture medium flat dishes used in clean areas are products that meet the expected quality requirements.
There are not many processes in the production process of petri plates, but in the process of making petri plates for environmental monitoring in many microbiology laboratories, it is easier to ignore some process details, such as the use of single-layer packaging, non-final sterilization, etc. Although 100% pre-culture before use avoids "false positives", it also brings "false negatives" and cross-contamination of petri plates due to improper packaging protection.
Due to the limited production process of culture medium, the culture medium flat dishes used in some university microbiology laboratories and some pharmaceutical companies' microbiology laboratories are still prepared and used according to the components of the culture medium, and some are prepared and used by themselves using dehydrated media produced according to the regulations. However, according to the requirements of the preparation of culture medium in the General Rule 9203 of the Pharmacopoeia of the People's Republic of China "Guiding Principles for Quality Management of Pharmaceutical Microbiology Laboratories", it is difficult to meet the needs of environmental monitoring in clean areas by hand. Therefore, in the context of strict regulations and generally improved quality awareness, the culture medium flat dishes used for environmental monitoring in clean areas are basically commercialized pre-packaged culture medium flat dishes.
The production process of each product is unique, and the same is true for the pre-packaged culture medium plate, but the quality control of the culture medium has common key factors, such as personnel, culture medium, strain, verification, equipment, and documentation.
personnel
Personnel are the most crucial elements in production activities. They must not only manage materials and control equipment, but also develop procedures and manage the environment. Every process of production is controlled by people.
Personnel should receive appropriate training according to their positions and responsibilities, such as training in equipment operation, microbiological inspection techniques, etc. necessary for competent work, including aseptic operation, medium preparation, disinfection, sterilization, plate packing, colony counting, strain transfer, passage and preservation, microbiological inspection methods, etc., and can only be hired after passing the assessment.
medium
As the raw material of the finished culture plate, the culture medium is the basis of microbial test and directly affects the results of microbial test. Appropriate storage conditions and quality control tests are the guarantee of providing high-quality medium. Therefore, the quality of the dehydrated medium must be checked before production, such as pH value, microbial growth promotion test, etc., which is also the first condition to ensure that the culture medium plate meets the quality requirements.
strain
According to the requirements of the Chinese Pharmacopoeia, the laboratory should have standardizedstrainProcedures for handling and preservation to minimize strain contamination and alteration of growth characteristics. Strains prepared by standard operating procedures are an important guarantee of consistency in microbial test results.
The resuscitation, rejuvenation or preparation of the culture of the standard strain shall be carried out according to the instructions provided by the supplier or according to the verified method. The standard strain obtained from the domestic or foreign strain preservation institutions shall be the standard reserve strain after it has been revived and grown in a suitable medium. The purity and characteristics of the standard reserve strain shall be confirmed. When the standard reserve strain is stored, the culture can be suspended in aliquots in the freeze-resistant medium and divided in vials. It is recommended to use the methods of cryogenic freeze-drying, liquid nitrogen storage, and ultra-low temperature freezing (below -30 ° C). The storage time of the strain can be extended by the method of cryogenic freeze-drying below -70 ° C or cryogenic freeze-drying. The standard reserve strain can be used to prepare working strains that are transplanted once a month or once a week. Once the frozen strain is thawed and transplanted to prepare the working strain, it must not be re-frozen and reused.
The number of passages of working strains should be strictly controlled and should not exceed 5 generations (the standard strain obtained from the strain preservation institution is the 0th generation) to prevent excessive passages from increasing the risk of strain variation. Generation 1 refers to the inoculation of live cultures into fresh medium for microbial growth. Any form of transbreeding is considered to be one passage. When necessary, the laboratory shall confirm the characteristics and purity of the working strain.
The working strain cannot replace the standard strain, and the commercial derivatives of the standard strain can only be used as the working strain. If the standard strain is proved to have aged, degraded, mutated, polluted, etc., or the strain is no longer needed for use, it should be sterilized and destroyed in time.
The laboratory must establish and maintain records of the entry and exit, collection, storage, confirmation tests, and destruction of all its strains, and should document the procedures for strain management (from standard strains to working strains), which include: the purchase record of standard strains; the operation and records from standard strains to working strains; strains must be regularly transferred and passed on, and key indicators required by the laboratory such as purity and characteristics must be confirmed and recorded; each strain should indicate its name, standard number, inoculation date, and number of generations; the medium and culture conditions for the growth of strains; the location and conditions for the preservation of strains; other required procedures.
verify
Whether it is self-prepared or commercialized production of finished pre-loaded culture medium flat dishes, first of all, there must be verification of sterilization procedures, that is, the medium should be sterilized by the verified sterilization procedure, and the sterilization method and conditions of the medium should be verified by sterility test and growth promotion test. Secondly, the steam circulation system of the autoclave should also be verified to ensure the normal heat distribution under a certain loading method. Third, the agar plate is best used now. If it is stored in the refrigerator, it should generally not exceed 1 week, and it should be tightly packed. If the storage period is extended, the storage period needs to be verified and determined, that is, the stability of the product should be inspected. Fourth, the process verification of the product. In the laboratory, if the medium is prepared using a validated preparation and sterilization procedure and the process is controlled, the suitability check test for the same batch of dehydrated medium can be performed only once. If the preparation process of the medium is not validated, the suitability check test is performed for each sterilized batch of medium.
equipment
The microbiology laboratory shall be equipped with instruments and equipment appropriate to the inspection capacity and workload. The type, measurement range and accuracy level shall meet the requirements of the standards adopted for the inspection. The installation and layout of the equipment shall be easy to operate, easy to maintain, clean and calibrate, and keep clean and in good working condition. Each instrument and equipment used for testing shall be uniquely identified.
Instruments and equipment should have a certificate of conformity, and the laboratory should complete the corresponding verification, calibration, verification, and confirmation of their performance, and form corresponding standard operating procedures for operation, maintenance, and maintenance before they can be officially used. The use and daily monitoring of instruments and equipment should be recorded.
file
In the case of self-prepared petri dishes in a laboratory, the documentation should fully demonstrate that the test was conducted in the laboratory according to a controlled inspection method, generally including the following aspects: personnel training and qualification confirmation; equipment acceptance, verification, verification (or verification during calibration) and maintenance; equipment operating status in use (key parameters of equipment); medium preparation, storage and quality control; strain management; key steps in the inspection procedure; data recording and confirmation of result calculation; data deviation adjustment.
Since the culture medium plate is a medical apparatus product, its production enterprises must strictly follow the "Medical Apparatus Production Quality Management Specification" to formulate relevant guidance documents to guide production, such as process regulations, Quality Standards, and various operating procedures.
Overall, the quality of the finished pre-packaged culture medium plate is produced, so every step in the production process should be strictly controlled during the production process, focusing on the entire quality system, such as the standardized operation of personnel, the quality control of materials, the strict and standardized production process, and scientific quality control.
