ASEPTIC TECHNIQUE: A GOAL TO STRIVE FOR IN COLLECTION RECOVERY OF MOLDY ARCHIVAL MATERIALS AND ARTIFACTS
MARY-LOU E. FLORIAN
4 4. ASEPTIC TECHNIQUE: A LOGICAL PREVENTION OF FUNGAL PROBLEMS
Aseptic technique uses procedures that prevent fungal cross-contamination from moldy to nonmoldy objects, thereby reducing future fungal problems. The technique also prevents an increase in the level of airborne conidia in the work site, thereby reducing health hazards and hazards to other objects.
The recovery process includes initial storage and/or treatment, dehydration of the wet objects, and then decontamination of the dry objects.
4.1 4.1 INITIAL STORAGE AND TREATMENT, INCLUDING DEHYDRATION
The initial storage and/or treatment may be at the disaster site, or at another site, or in cold storage or freezing facilities. Aseptic technique must be considered in all activities: the packing and unpacking techniques, transportation process, protection of objects that are just wet and not moldy, drying methods such as air movement or exposing surfaces, and facilities maintenance. Drying method may involve air flow, dehumidification, heat (less than 37°C), and freeze-drying. The pros and cons of the different storage facilities and drying methods are discussed by Mary-Lou Florian (1997).
4.2 4.2 Decontamination
Decontamination reduces the conidia numbers, thereby reducing health hazards and the potential for future fungal problems on the objects. Decontamination involves two steps: the killing and the removal of the conidia and the mycelia. Drying the objects will kill the hydrated mycelia and conidia but not dormant, nonactivated dry conidia. Therefore the conidia and mycelia must be removed, even if they are dead. In exceptional cases where a toxic fungus has contaminated materials, killing all the fungal structures is essential prior to cleaning to prevent the spread of viable conidia, but the fungal structures still need to be removed to reduce the health hazard.
Decontamination methods include surface cleaning by vacuuming, electrostatic dusting, brushing, erasing, and dry-sponging. Because there is little literature on the success of these methods, it is essential that, prior to object treatment, the methods are tested for their efficiency. They must also be assessed in reference to aseptic technique.
A normal background of airborne conidia will be present at every collection recovery site, but the number of conidia can increase dramatically in the presence of moldy objects. Using aseptic techniques can drastically reduce their presence. We cannot hope to eliminate all the conidia, however, because as soon as cleaned objects are placed in air, they become contaminated with conidia from normal airspora.
The greatest threat to mold-free objects or objects that have been decontaminated is cross-contamination from moldy objects, contaminated materials, and airborne conidia. Contaminated materials include anything that may have come in contact with the moldy objects, such as packing cases or boxes, packing materials, gloves, brushes, and other tools used during cleaning, and even the surfaces they are put on for cleaning.
4.3 4.3 ASEPTIC TECHNIQUE STEPS
Most aseptic technique steps are simple and logical, but they require a new awareness in our procedures. The following is a preliminary list of steps to improve aseptic technique:
- Cover moldy and wet or damp objects with water-permeable material during transport or storage. If the objects are dry, they can be placed in clear polyethylene bags. Do not reuse packing materials unless they have been decontaminated.
- Isolate moldy objects from those that are not moldy.
- Reduce air movement in the storage or cleaning area.
- Keep the work area free of contamination. Wipe table surfaces with disposable cloths dampened with 70% ethyl alcohol or a commercial disinfectant. An exhausting fume hood is desirable for cleaning dry moldy objects, but if one is not available, there are alternatives, such as an elephant trunk or a vacuum cleaner tube adjacent to the cleaning activities that exhausts into HEPA filters external to the work room.In mycological laboratories the fume hood is decontaminated by wiping it down with 70% ethyl alcohol and or treating it with ultraviolet lights at night when staff members are not present. These lights also have external UV reflector shields that are pulled down during UV treatment to protect the staff's eyes.
- Make sure vacuums deposit conidia and debris onto filters. A series of filters with different pore sizes is efficient because the coarse filter will capture large material, and the last filter, the HEPA filter, captures the conidia. The exhaust of the vacuum should not allow air movement around the cleaning site. Exhaust the vacuum into an adjacent room, or use a central vacuum system. If the vacuum does not use a HEPA filter, attach one to its exhaust.
- During cleaning, place the moldy object on a sheet of inexpensive paper that can be folded into itself and disposed of after the object is cleaned. Select a paper with the right electrostatic nature; it must attract the negatively charged conidia.
- Immediately after cleaning, place the cleaned, dry object in a labeled, clear polyethylene bag.
- Clean gloves during and after the cleaning of each moldy object. While the gloves are still on your hands, you can wipe them with a cloth dampened in an alcohol solution or commercial disinfectant, or you can wash your gloved hands in a disinfectant soap solution, followed by thorough water rinsing.
- Decontaminate tools during and after the cleaning of each moldy object. Vacuum brushes or zone collectors and hand tools can be washed with a 70% ethyl alcohol or isopropyl alcohol solution.
- Decontaminate packing materials, tools, paper, etc. that need to be reused by vacuuming, autoclaving, pressure cooking, oven heating, or using boiling water as appropriate.
- Remove garments, particulate masks, and gloves by turning them inside out and folding them into themselves before disposing of them in a designated container.
- Dispose contaminated wastepaper, gloves, etc. in such a way as to isolate the wastes and prevent conidia going into the air when the container is opened. Incineration of wastes is recommended.
Every collection recovery is unique, so methods and procedures will be specific to each situation, but the philosophy of aseptic technique should direct these methods or procedures.