Michael Miller, Ph.D.
Associate Director for Laboratory Science
National Center for Emerging and Zoonotic Infectious Diseases
Centers for Disease Control and Prevention
1600 Clifton Road, NE
Atlanta, GA 30333
Dear Dr. Miller:
The American Society for Microbiology (ASM) welcomes the opportunity to review and comment on the Guidelines for Safe Work Practices in Human and Animal Clinical Diagnostic Laboratories. The Committee on Laboratory Practices of ASM’s Public and Scientific Affairs Board submits the following comments for your consideration:
3.1 (p. 41):
● Ideally, all specimens are to be processed in a biological safety cabinet (BSC) adhering to safe BSC practices.
ASM recommends that this chapter include specific safety details for those laboratories that do not have BSCs. Many clinic laboratories do not have BSCs but still process specimens for direct/rapid testing. The guidelines should inform these laboratorians how to process different specimens safely, e.g., for influenza and respiratory syncytial viruses, using a splash shield, laboratory gown and gloves. A series of examples would be helpful.
3.1.4 (p. 45):
● Risks include handling live organisms in concentrated amounts, the potential for creating aerosols, the potential for skin contamination and environmental contamination.
The ASM recommends that the document define ‘concentrated’ samples. A lack of a definition has lead to confusion for many laboratories (i.e., STEC toxin). Additional guidance would be helpful in understanding whether an over-night broth tube culture, a liter, or more grown up culture for study purposes is recommended.
3.2 (p. 48):
If engineering controls are in place to prevent splashes or sprays from occurring, the requirement for PPE may be modified based on a risk assessment and evidence of the effectiveness of the engineering control to prevent exposure from splashes or sprays.
ASM recommends that the CDC consider including specific details regarding the “engineering controls” it envisions.
3.2.1 (p. 49):
Safety glasses, splash shield, surgical mask, and gloves should be available for optional use and when necessary based on the isolate.
ASM recommends that the CDC provide specific examples on which isolates might warrant glasses, shields, masks and gloves.
3.2.1 (p. 49):
● Sniffing of bacterial cultures growing on artificial media to detect characteristic odors may or may not increase the risk of laboratory acquired infections but there is little or no scientific evidence that defines the risk or implicates sniffing as a dangerous activity. It is prudent, however, to refrain from sniffing plates as a precaution and to reduce any risk to as low as possible.
These two statements are in contradiction. ASM suggests that if there is no evidence for or against a practice, why recommend it?
3.2.1 (p. 50):
● Computer keyboards located at workstations should have a protective cover that is easily cleanable and should be disinfected along with the benchtop on a routine basis, but at least at the end of the work shift.
The ASM is not aware that this is recommended nor how often used in daily practice.
3.2.2 (p. 51):
In some situations where it is impractical to work in a biological safety cabinet, personal protective equipment may form the primary barrier between personnel and hazardous materials(1).
ASM recommends that CDC define specific PPE that should be used per regulations if processing or testing not performed within a BSC, e.g., that in some situations where it is impractical to work in a BSC, both PPE and a splash shield may be necessary.
4.1 (pp. 114- 115):
The specimens are then moved to the tuberculosis laboratory where all procedures for TB specimen decontamination, culture propagation and subsequent manipulation of the cultures, are performed using BSL-3 facilities, containment equipment, practices and respiratory protection (1). The BSL-3 must be properly maintained, certified, and the door to the lab kept closed.
The ASM is concerned about using BSL-3 facilities for all AFB procedures, because it would put most laboratories out of the mycobacteriology culture business. It would also be cost prohibitive for many laboratories performing mycobacteriology to retrofit the laboratory to conform to a BSL-3 facility. For example, BSL-2 + facilities with BSL-3 practices are safe when performing many procedures in the clinical mycobacteriology laboratory, such as specimen decontamination, smear preparation, culture and DNA probe identification. A BSL-3 laboratory may also be necessary when other procedures, such as HPLC and susceptibility testing are performed on known isolates of M.tuberculosis due to the degree of manipulation of high-titer TB cultures (this would not be true for culture of non-TB isolates). The ASM recommends that the CDC further clarify the use of BSL-2 with BLS-3 practices and the use of BSL-3 practices and facilities for all AFB procedures involving both TB and non-TB isolates.
In addition, ASM recommends that CDC change “tuberculosis” laboratory to “mycobacteriology” laboratory, and change “TB” to “AFB” because most laboratories culture for mycobacteria, not just TB.
Again, the ASM appreciates the opportunity to provide comments on CDC’s biosafety guidelines for clinical diagnostic laboratories. Please let me know if you require additional clarification of our comments.
Susan E. Sharp, Ph.D., Chair, Committee on Laboratory Practices