target="_blank" rel="nofollow" href="#ulink_288a5ca1-1da3-5124-be45-911c46f082c3">Biological Safety Cabinet
The Class II-A1 or II-A2 biological safety cabinet (BSC) is best suited and recommended for the diagnostic laboratory. BSCs operate at a negative air pressure with air passing through a HEPA filter, and the vertical airflow serves as a barrier between the cabinet and the user. Although a BSC is not required for processing routine specimens in a diagnostic parasitology laboratory, some laboratories use class I (open-face) or class II (laminar-flow) BSCs for processing all unpreserved specimens (3). Use of a BSC is recommended if the laboratory is performing cultures for parasite isolation. However, remember that BSCs should not be used as fume hoods. Toxic, radioactive, or flammable vapors or gases are not removed by HEPA filters (8).
Maintenance (5)
1. After each use, disinfect the work area. Since UV radiation has very limited penetrating power, do not depend on UV irradiation to decontaminate the work surface (9). At least weekly, clean UV lamps (in the off position) with 70% isopropyl or ethyl alcohol.
2. At least annually, have class I BSCs certified. They should also be certified after installation but before use and after they have been relocated or moved. Certification should include the following and will be documented by the trained company representative (contracted to handle the BSC inspection).
A. Measurements of the air velocity are taken at the midpoint height approximately 1 in. behind the front opening. Measurements should be made approximately every 6 in.
B. The average face velocity should be at least 75 linear ft/min. A thermoanemometer with a sensitivity of ±2 linear ft/min should be used (10).
C. With the cabinet containing the routine work items, such as a Bunsen burner, test tube rack, bacteriological loop and holder, etc., a smoke containment test should be performed to determine the proper directional velocity.
D. Record the date of recertification, the names of the individual and company recertifying the cabinet, and any recommendations for future service. Any maintenance performed should also be documented in writing.
3. Replace the filters as needed.
4. On installation, have a class II BSC certified to meet Standard 49 of the National Sanitation Foundation, Ann Arbor, MI (10). The cabinet must also be recertified at least annually and/or when it is moved, after filters are replaced, when the exhaust motor is repaired or replaced, and when any gaskets are removed or replaced. Record the date of recertification, the names of the individual and company performing the service, and any recommendations for future service.
Any general-purpose laboratory (non-explosion-proof) or household-type refrigerator-freezer (4 to 6°C) can be used in the parasitology laboratory. Solvents with flash points below refrigeration temperature should not be stored, even in modified (explosion-proof) refrigerators.
Maintenance
1. On a daily basis, monitor and record the temperature of the refrigerator. The thermometer should be placed into a liquid to permit stable temperature recording, or thermocouples may be used.
2. On a daily basis, monitor and record the temperature of the freezer. The thermometer should be placed in antifreeze (any brand with freezing point below that of the freezer, e.g., ethylene-glycol-water solutions, glycerol-water solutions, or Prestone) to permit stable temperature recording. Thermocouples may be used instead.
3. Periodically when the door is opened, check to see if the fan is operational.
4. Monthly, check the door gasket for deterioration, cracks, and proper seal. Seal problems are often seen when ice begins to build up in a freezer or the temperature is not holding. Periodically, petroleum jelly can be rubbed onto the door gasket to lubricate the material and to help maintain flexibility for a tight seal when the door is shut.
5. Semiannually, clean the condenser tubing and air grill with a vacuum cleaner.
6. Semiannually, check to ensure that the drain tubes are kept open.
7. Annually, wash the interior with a warm solution of baking soda and water (approximately 1 tablespoon/qt [ca. 13 to 14 g/0.946 liter]). Rinse with clean water, and dry. Also, wash the door gasket and water collection tray with a mild soap and water. If the gasket accumulates a black mold, scrub with 50% household bleach solution and a small brush. Rinse with clean water, and dry.
Supplies for the diagnostic parasitology laboratory are often identical to those needed for routine work in other areas of microbiology. Although not every size of glassware used is specified, the list below should be helpful for anyone setting up a laboratory for this type of work.
1. Disposable glass or plastic pipettes and bulbs (some sterile for culture work)
2. Pipettes: 1, 5, and 10 ml (some sterile for culture work)
3. Glass slides (1 by 3 in., or larger if preferred). Slides with rounded edges are now available (safety-“sharps”).
4. Coverslips (22 by 22 mm; no. 1 or larger if preferred)
5. Beakers, 250, 500, 1,000, and 2,000 ml
6. Covered Coplin jars or staining dishes (with slide rack)
7. Graduated cylinders, 50, 100, 500, and 1,000 ml
8. Mortar and pestle (range of sizes)
9. Flasks, Erlenmeyer, 500 and 1,000 ml
10. Flasks, volumetric, 500 and 1,000 ml
11. Bottles, brown, 150 to 200 ml
12. Bottles, clear, 100, 500, and 1,000 ml
13. Bottles, airtight, 50 ml
14. Funnel (glass) to hold filter paper
15. Büchner funnel
16. Centrifuge tubes, 15 and 50 ml (some with screw caps)
17. Petri dish, plastic, sterile
18. Tubes, screw-cap, 13 by 100 mm or 16 by 125 mm (some sterile for culture work)
19. Plastic syringe, 15 ml
20. Sterile syringes (glass or plastic), 1, 10, 20, and 50 ml
1. Culture tube racks
2.
