Biosafety in the Laboratory Prudent Practices for Handling and Disposal of Infectious Materials (1989) / Chapter Skim
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3 Safe Handling of Infectious Agents
3 Safe Handling of Infectious Agents
Pages 13-33
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From page 13... ...
, on the other hand, poses a low risk of occupational infection to laboratory workers, except to those working with concentrated virus suspensions [37,1431. The supplement to the CDC/NIH guidelines recommends, therefore, that HIVs be handled according to the standards and special practices of Biosafety Level 2 or 3, depending on the concentration or quantity of virus or the type of laboratory procedure used (see Appendix B)
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From page 14... ...
While it is recognized that many of the agents listed are not significant hazards under ordinary laboratory circumstances, laboratory staffs should recognize the dangers of zoonotic pathogens and should realize, for example, that protozoan cysts and larval stages of certain helminths in fecal material can be infectious [261. Application of the seven basic rules of biosafety cited in Section F of this chapter will greatly reduce the risks of infection while handling vertebrate animals or specimens obtained from them (see also Section G of this chapter)
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From page 15... ...
Laboratory workers handling tissues and cell cultures from African green monkeys developed an acute febrile illness. Seven deaths occurred among 31 documented cases due to a previously unknown virus, subsequently named Marburg virus.
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From page 16... ...
The National Committee for Clinical Laboratory Standards DECALS) has published proposed guidelines, entitled Protection of Laboratory Workers from Infectious Disease Transmitted by Blood and Tissue, that include necropsy and tissue handling recommendations [901.
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From page 17... ...
The British Committee on Dangerous Pathogens has suggested performing limited postmortem examinations with discrete tissue sampling for most AIDS cases [il. Any spills of blood or body fluid should be cleaned immediately with a solution of household bleach diluted 1:100 in tap water.
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From page 18... ...
It should be recognized that a large number of procedures may result in the generation of a mixture of droplets and aerosols with the result that exposure by more than one route is possible. While it has been typical to focus on respirable aerosols as the primary source of infection for laboratory personnel, it is essential that other routes of exposure be considered: contact, oral, ocular, and inoculation.
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From page 19... ...
3. Prevention of Exposure The time-honored approach for the safe handling of infectious agents involves the use of a combination of strategies.
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From page 20... ...
Laboratory workers should be aware of these potential hazards and exercise a high degree of care during all manipulations of infectious materials. As evidenced by the data accumulated in the review of laboratory-acquired infections by Pike [1011, ex posure of laboratory workers is not often associated with overt accidents.
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From page 21... ...
Microbiological practices, including the wearing of laboratory coats, gloves, or other protective clothing, should be followed as applicable. A Class I or Class II biological safety cabinet provides the most suitable work station for opening packages and for He initial handling of incoming specimens [86]
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From page 22... ...
Emergency plans should be posted in a conspicuous place in the laboratory for immediate reference. Emergency plans should provide written procedures for dealing with · breakage or spillage of infectious materials, · exposure of personnel to infectious materials by accidental injection, cuts, or other injuries, · accidental ingestion or contact of mucous membranes with potentially hazardous material, and · aerosols.
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From page 23... ...
When handling organisms for which Biosafety Level 3 precautions are indicated (e.g., etiologic agents of tuberculosis, systemic mycoses, or Q fever) , it is recommended that pipetting procedures be carried out in a biological safety cabinet.
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From page 24... ...
If generation of an aerosol is likely to occur during the processing of these specimens, the use of a biological safety cabinet is recommended strongly for these procedures. Improper technique in the flaming of inoculating loops can result in the spread of infectious agents.
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From page 25... ...
2. Biological Safety Cabinets Most laboratory procedures generate aerosols that may spread infectious material in the work area and pose a risk of infection to the worker.
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From page 26... ...
shows the airflow patterns and operating velocities for the five types of Class I and Class II biological safety cabinets produced in the United States. All of these biological safety cabinets provide a comparable level of protection for the user against exposure to infectious aerosols and droplets, in that the velocity of the protective inward airflow through the work opening is essentially the same.
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From page 27... ...
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From page 28... ...
Safety glasses, face shields, and masks may protect mucous membranes of the eye, nose, and mouth from splash or droplet hazards during operations performed outside of a biological safety cabinet.
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From page 30... ...
Where large-scale production is initiated in the process of commercialization of a desired product, the constraints enforced to ensure product integrity typically result in increased safety to personnel as well. As numerous laboratories have developed largescale production facilities for the commercialization of biological products, the need for carefully designed and implemented procedures has become increasingly important for the safety of laboratory workers, the community, and the environment.
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From page 31... ...
The specific minimum requirements for physical containment are described in the NIH "Guidelines for Research Involving Recombinant DNA Molecules" [1363. The large-scale containment classifications, BSL1-LS, BSL2-LS, and BSL3LS (Biosafety Levels 1, 2, and 3, large-scale, respectively)
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From page 32... ...
The more frequently used methods include settling plates, air impingers, and falters. Settling plates provide qualitative information and consist simply of an open petri dish containing appropriate culture medium onto which particles settle due to gravity.
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From page 33... ...
Indeed, all of the general principles outlined in this chapter for the safe handling of infectious agents apply to smallvolume laboratories as well as large-volume ones. Many of these small-volume laboratories may be 33 handling human blood or blood components that could be infectious.
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