When a manufacturing facility conducts microbial testing internally, the lab is expected to have hygiene and pathogen control programs in place and verified for effectiveness. These internal labs are to operate under their own quality systems, which may or may not be operated under the scope of an ISO 17025 platform.
Either way, the lab follows its own standard operating procedures and cross-contamination mitigation techniques with goals in keeping with the food safety systems employed by the facility that the lab is serving. A documented and carefully implemented laboratory environmental monitoring program (EMP) will provide the scientific evidence that sanitation activities are being conducted and pathogens are being controlled within the lab.
Hygiene monitoring and pathogen monitoring programs fall under the environmental monitoring umbrella and contain the same general elements of a manufacturing facility EMP including:
- Site selection and site lists;
- Assigning zones to each site;
- Determination of test organisms and test assays;
- Specification setting;
- Site selection randomization;
- Designated sampling times;
- Result tracking and trending;
- Corrective/preventive actions; and
- Verification activities.
It may seem as if you are seeing double—“hygiene monitoring” and “pathogen control programs” are the same thing, right? In a word, no. The main difference relates to the organisms that are tested. In a hygiene monitoring program indicator organisms are tested, while in a pathogen monitoring program all pathogen assays that are routinely run in the lab are tested. Similarities between the programs are that they both verify that cleaning and sanitation are effective as written and applied.
Assays and organisms tested. A hygiene monitoring program will use assays that yield quantitative as opposed to qualitative results. Quantitative results will give a numerical value and are reported in colony forming units (CFU/swab, CFU/sponge or unit of time for air plates). The assays include aerobic plate count (synonyms: total plate count, total viable count), Enterobacteriaceae, coliforms, E. coli, Enterococcus faecalis, yeast, and mold.
Sampling times and result interpretation. There are three sampling times, each of which will have a different objective:
- To assess cleaning/sanitation efficacy: Samples are taken after cleaning and before the application of a sanitizer, and then again after application of the sanitizer;
- To assess potential soil accumulation points: Sites include scales, water baths, and under and within pieces of equipment; and
- To assess the efficacy of Good Laboratory Procedures during lab operations: Sample times include after sampling powders, during and at end of operations.
Organisms. An aerobic plate count (APC) measures the number of bacteria that grow aerobically in media at the ideal growth temperatures of most bacteria. Results are obtained in 48 hours. An APC assay can assess the efficacy of cleaning and sanitization when sponges or swabs are taken immediately after the cleaning or sanitizing event. When the results are out-of-specification (OOS), management should view how cleaning/sanitation procedures are performed along with reviewing chemicals and application frequency. When areas such as door handles, carts, or incubator racks are swabbed during lab operations, the results can be used to provide an indication not only of their current microbial load, but also how often the sites are cleaned/sanitized and disassembled.
Enterobacteriaceae, coliform, E. coli, and E. faecalis test results are used for the same purposes as APC in ensuring hygienic conditions. They are particularly useful as indicators of environmental control (i.e., the removal of soil accumulation), whether the lab routinely runs tests for these organisms or not.
Yeast and molds are an indicator of air quality. The ventilation system in a lab may not be exclusive to the lab and monitoring can be used to assess air vent buildup that may impact the lab or the external environment. This is expressly indicated if the lab does not have HEPA filtration units. Mold is a common indication of water leaks and can be found in areas that have been exposed to water, especially when pooled.