Diagnostic Medical Parasitology. Lynne Shore Garcia
or fungal blood culture bottles to be set up for isolation of organisms must be processed in a BSC. All “open-system” work is to be done on an absorbent surface (i.e., a towel) in a BSC, using appropriate protective techniques. Towels should be changed daily. We recommend that the immediate working area of the towel be dampened with any recommended disinfectant to handle small spills (Fig. 11.3).
Figure 11.3 Example of a commercially available disinfectant (Solucide) that can be used for countertops, small spills, and any hard surface that requires a disinfectant (www.med-chem.com). doi:10.1128/9781555819002.ch11.f3
1. All specimens are potentially pathogenic—always use careful techniques (Tables 11.3 and 11.4).
2. All discard material used in processing of specimens is considered contaminated.
A. Fluids used in the processing of specimens (buffers, etc.), as well as excess liquid specimens, should be poured into plastic screw-top autoclavable bottles and sterilized prior to disposal. A tongue depressor placed in the bottle can help to prevent splashing if liquid is poured down the slanting stick. These sticks can also be placed in disinfectant before being discarded. Disinfectants and incineration can also be used for decontamination of infectious materials.
B. Reusable items (tissue grinders, bottles, etc.) are placed in an autoclave pan. Once the pan is full, place it (without a cover) in a large brown autoclave bag and staple shut. After being autoclaved, the reusable items can be cleaned.
C. Specimen containers and centrifuge tubes are disposable. These items should be placed in plastic autoclave bags and secured with masking tape for sterilization. Slides can also be placed in containers of liquid disinfectant prior to disposal. Remember, slides should be treated as sharps.
D. Pipettes can be placed in a covered discard pan containing 5% amphyl or placed in autoclavable containers for sterilization before discarding.
1. Disinfectants in use at present
A. Bleach solutions. To be an effective disinfectant, working bleach solutions must contain >0.5% but <2% sodium hypochlorite. Hypochlorite concentration in household bleach varies by manufacturer. Many household bleach solutions contain 5.25% sodium hypochlorite, and a 1:10 dilution (5,000 ppm Cl) will produce a 0.53% hypochlorite solution. Use of bleach solutions with lower hypochlorite concentrations might not provide the proper level of disinfection. Each day, prepare a fresh 1:10 household bleach solution (3, 23).
B. Alcohols. Alcohols generally act by coagulating proteins and as organic solvents. Rapid evaporation may lead to inadequate “killing” time. Although there are some conflicting reports, 70% solutions generally have the best microbicidal activity. Caution is advised because of flammability. DO NOT USE ALCOHOLS OR ALCOHOL-BASED SOLUTIONS ALONE TO DISINFECT SURFACE AREAS; EVAPORATION SUBSTANTIALLY DECREASES EFFICACY.
C. Another option can be seen in Fig. 11.3.
Note Use disinfectants recommended for environmental surfaces, such as Environmental Protection Agency (EPA)-registered disinfectants effective against hepatitis B virus, human immunodeficiency virus (HIV), and other blood-borne pathogens, or use a 1:10 dilution of household bleach. EPA environmental disinfectant product registration information is available at http://www.epa.gov/oppad001/chemregindex.htm (accessed 9/11/2013).
2. Immediate actions
A. Clear the area at once.
B. Notify the supervisor and chief of microbiology.
C. Assess the type of spill and degree of hazard involved.
D. Determine the most effective and least hazardous approach to clean up and decontaminate.
3. “Dry spills” with no significant aerosol formation
A. Flood the area with disinfectant solution.
B. Soak up disinfectant and contaminated material with absorbent material (sand or paper towels), and dispose of it in a plastic biohazard bag or sealed container. Wear gloves for cleanup.
C. If routine cleanup is not possible, the unit may have to be decontaminated with a sterilizing gas such as paraformaldehyde.
D. Thoroughly wash the unit (if possible) after decontamination.
4. Liquid spills on the bench or floor
A. If significant aerosols were formed, the area should be evacuated and not reentered for at least 1 h.
B. Flood the area with disinfectant, and cover the spill with absorbent material (sand or paper towels). Wear gloves during cleanup.
C. Dispose of absorbent and contaminated material in plastic bags or sealed containers, and autoclave.
D. Thoroughly wash the area after cleanup.
5. Centrifuge spills
A. Shut off the instrument, and evacuate the area at once.
B. Do not reenter the area for at least 1 h until aerosols have settled.
C. The person entering the area to clean up should wear protective clothing, gloves, and a mask.
D. If liquids are present, soak up in absorbent material and handle as above. If liquids are not present, clean the instrument and room thoroughly before resuming work.
E. Wipe all surfaces with a recommended disinfectant.
6. Spills in incubators, autoclaves, or other closed areas
A. Flood with disinfectants, and soak up liquids with absorbent material.
B. Dispose of the material as specified above, if possible.
C. If routine cleanup is not possible, the unit may have to be decontaminated with a sterilizing gas such as paraformaldehyde.
D. Thoroughly wash the unit (if possible) after decontamination.
Disposal of Contaminated Materials (3, 24)
1. Autoclave screw-cap tubes before cleaning or discarding.
2. Discard specimens and cultures into containers with double plastic lining. Liners should be changed when the containers are about half full.
3. Place culture plates into “Biohazard” receptacles lined with autoclavable bags.
4. Materials or containers to be reused should be autoclaved before being cleaned. Place them in sealed and clearly labeled containers to minimize hazard to others before sterilization.
5. Any breakage of glass or leakage of