Like high-functioning food manufacturing facilities, high-functioning food microbiology laboratories should conduct a number of validation and verification activities to demonstrate their processes are under control. Similar to how a food manufacturer must develop and validate its FSMA-required Food Safety Plan, food microbiology laboratories also should conduct a hazard analysis, develop preventive controls for hazards reasonably likely to occur, use monitoring to validate preventive controls and for routine verification activities, develop corrective actions when out-of-spec results are obtained, and keep records for all activities. (In this case, a micro lab “hazard” is the risk of cross-contaminating client samples with out of control microorganisms in the laboratory environment.)
To ensure that laboratory test results are accurate, consider the following:
- Does company management have a conflict of interest in testing programs, and are there protocols in place to mitigate such conflicts?
- Are laboratory employees trained in ethical behavior regarding proper sample collection, testing, and reporting?
- Are there written non-conformance policies?
- Are there undue influences that impact test data integrity?
- Are the methods used fit for their purpose?
Well-performing microbiology laboratories are accredited against ISO17025 standards. The standard includes a focus on yearly employee training, a well-documented laboratory quality system, reason, length, and documentation of planned departures, and regular audits. In addition, USDA provides a laboratory guidance document.
Employees must know the purpose of policies and procedures, the principles of procedures, how to do calculations, understand QC practices, how to keep records, how to correlate test results, and how to keep training documentation. Environmental monitoring can provide useful data points to help validate procedures and routinely verify compliance.
Fit for Purpose
The laboratory physical plant must be fit for purpose. Adequately maintained pest control, lighting, walls, ceilings, and floors are needed. Ensure hot water handwash stations are provided and impervious benchtops for sanitation are used. Air HEPA filtration and positive pressure help prevent laboratory cross-contamination. Regularly conduct air contaminant monitoring and zone environmental pathogen monitoring. Address glove change frequency and adequacy of use. If the laboratory is doing pathogen testing, is it Biosafety Level II compliant?
Individuals trained in proper laboratory cleaning should do laboratory housekeeping on a regular schedule. Care should be taken if these individuals also clean the food facility due to cross-contamination risk. Follow proper standard sanitary operating procedures, with regular environmental monitoring verification conducted for pathogens. Cleaners and sanitizers should be fit for purpose. Check for the presence of cleaning residue on all glassware before use. Keep records of all activities.
All laboratory equipment must also be fit for purpose. Properly maintain such equipment on a regular preventive maintenance schedule and calibrate on a routine appropriate for the equipment. Difficult-to-sanitize equipment should have sanitation standard operating procedures detailing such routine. Usual suspects include pipetors, stomachers, auto preps, balances, and glass/plastic ware. Environmental monitoring of this equipment can verify its sanitary condition before use.
Media performance should be routinely checked. Perform productivity, selectivity, and sterility tests on each medium batch. Statistical process control chart use is advised for quantitative testing. The media preparation autoclave needs to be of suitable size to sterilize media batch sizes in use. In addition, do not use media prep autoclave to decontaminate spent media and contaminated materials. Rather, a separate decontamination room and separate autoclave is preferred.
Media fill volumes should be validated and routinely monitored, including petri plates, dilution blanks, MPN tubes, and slant volume and butt height. Likewise, routinely measure water quality and final media pH. If media sterility is questioned, there may be potential for environmental contamination. Monitoring for this potential will allow for quicker resolution of sterility issues if they occur.
There are many questions that need to be addressed in regard to sample collection. Have employees been trained on aseptic technique? Samples should be held at the appropriate temperature in impervious sample containers. Upon receipt, are samples and tests adequately described, and are the chosen tests fit for purpose? Are samples fit for analysis—what is sample integrity upon receipt and are they held under adequate storage conditions? What is the potential for sample cross-contamination during handling, and is this potential routinely measured through environmental monitoring?