Examining the Differences Between Pathogen Control Programs and Hygiene Monitoring

There are a number of methods to monitor air quality. The use of an air sampler that draws air and impales it onto a petri dish is a valuable tool because it draws in large quantities of air. Alternatively, passive air monitoring (settling plates) is a common, inexpensive method to collect samples wherein media is exposed to operational air for a predetermined amount of time (commonly 15-45 minutes) and the plates are then incubated. Normal operations should be taking place during air monitoring.

Pathogen Control Programs

Assays and organisms tested. A pathogen control program will use assays that yield qualitative as opposed to quantitative results. Qualitative results will yield a negative or positive and are reported per gram weight of the sample tested or per sponge/swab. The assays usually include an enrichment step that will repair injured cells and allow cells, if present, to multiply to a concentration that can be detected by the assay. Detection limits, the lowest concentration required for a positive result, varies according to the assay. Some assays are more sensitive than others. Cross-reactivity (false positives) may occur with some organisms that have genetic similarities to the target. Test kit manufacturers have information on detection limits and false positive rates available. With all assays, confirmation that the assay is suitable to the matrix (sample tested) is always an important component prior to testing.

Organisms. Organisms tested within a pathogen control program are the same as those used for the samples tested in the lab. However, it is not necessary to run all testing platforms if the lab uses multiple methods when testing samples. Select one platform and assay sponges/swabs taken at various lab locations for all the pathogens that are tested in the lab. Select sites where the pathogens are sampled, incubated, handled, and discarded within the lab. Do not exclude technician lab coats, gloves, or common areas such as sinks, cart paths, and locations where hand contact may occur.

Laboratory EMP Components

Compiling site list. Each lab area where the samples are logged-in/staged, media prepared, dishes washed, assays conducted, plates read, and transfer points must have representation within the site list. Within each area, all equipment used, environmental areas (walls, floors, cabinets), and utensils are to be accounted for on the site list. The site list should be reviewed on a periodic basis to account for equipment added or removed, construction or site modifications, and any facility issues such as roof leaks. Plotting all sites on a lab diagram is a step to help determine that each area and piece of equipment has been represented.

Assignment of zones. Similar to the manufacturing plant, site zones are designated as Zones 1 through 4:

• Zone 1: Any surface where a sample has contact (e.g., pipette tip, sampling scoops, mixing vessel);
• Zone 2: Adjacent to sample contact (e.g., lab coat, gloves, stomacher, centrifuge, handles, laminar flow hoods and bio-safety cabinets, scale, control panels);
• Zone 3: Equipment and infrastructure where samples are exposed (e.g., cabinets, carts, hand wash sinks, floor/floor mat); and
• Zone 4: Hallways leading into or out of the lab, air ducts exterior to the lab, pathways to remove waste, offices.

Sample selection and frequency. Sample selection from the site list should be randomized. The use of a random number generator is recommended so that all sites will have an equal chance of selection. The goal is for each sample site to be tested at a desired frequency. For example, if the lab has 200 sites on the site list and the lab would like each sample to be tested within a quarter and samples taken on a weekly basis, then approximately 13 samples are to be tested per week (See Table 1). This volume will increase if the same site is sampled immediately after cleaning, after sanitation, during lab operations, and at the end of the operational day.