February 4, 2005 - ASM Comments on CDC's draft Guidelines for Preventing the Transmission of TB in Health Care Settings, 2005

The American Society for Microbiology (ASM) is pleased to provide comments to the Centers for Disease Control and Prevention (CDC) on its draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Settings, 2005, as announced in the Federal Register on December 6, 2004. The ASM is the largest scientific society dedicated to the advancement of the microbiological sciences and their application for the common good. The Society represents more than 42,000 individual members who work as researchers, educators, clinicians, administrators and technical personnel in academic, industry, government, clinical and public health laboratories and institutions.

The ASM commends the CDC for its work on this important document which addresses infection control of Mycobacterium tuberculosis. ASM’s Committee on Laboratory Practices reviewed the draft Guidelines and limits its comments to those issues pertaining to pathology and laboratory sciences. The attached chart outlines ASM’s recommended changes to the draft Guidelines. ASM appreciates the opportunity to comment on this matter. Please contact us if you require additional information.

Joseph M. Campos, Ph.D.
Chair, Committee on Laboratory Practices
Public and Scientific Affairs Board

No. Page Section Item Suggested Changes in BOLD type
1. 17  A.1 Pathologist, Pathology Lab Staff(Modifies 2, Adds 1) a) Pathologists; b) Histopathologists and tissue processors; c) Autopsy staff and students   (all = very high risk)  (“Pathology laboratory staff” can mean Lab staff; omits the two most dangerous areas of tissue grossing and autopsy work.)
2. 17 A.2 TB patients “visit” Suggest “TB patient exposure occurs... (Patients don’t “visit” autopsy suites, etc.)
3. 20 B.1 Addition to listing Microbiology staff processing TB cultures  (Many consider the centrifugation and vortexing steps used to prepare concentrated specimens for smears and cultures also high risk step, e.g. not only processing of positive cultures.)
4. 21 B.3 Presence of cough Presence of a chronic cough (or presence of a persistent cough)
5. 24 D.1 “Ensuring timely.... reporting of results” Ensuring timely...reporting of results to the ordering physician and Infection Control 
6. 32-34 B.3 Add to medium risk list: Mycobacteriology Laboratory  (B.7a, and B.8, 9, and 10 all apply)
7. 38 Last table Culture systems b) Culture using liquid media (e.g. Bactec, MB-BacT, Midget system) (Increasingly used due to issues with the two listed)
8. 53 Bullet 3 Suggest major safety upgrade in this. Experience shows that the risks of centrifugation, for example, (including opening of carriers with unexpectedly broken or cracked tubes is unappreciated in labs that use the concentration step, and subsequently send positives elsewhere. Suggest flag what is meant by “non-aerosol-producing steps” as follows:   Biosafety level BSL-2 practices procedures, containment equipment, and facilities are generally effective for manipulation of clinical specimens for procedures that are non-aerosol producing.  BSL-3 practices and containment equipment are necessary for procedures that produce aerosols such as specimen vortexing or centrifugation steps, as well as for all work involving the processing of positive cultures. 
9. 68 D4.2b Diagnostic availability considerations: b)  rapid NAA testing for direct detection of M. tuberculosis in smear positive patient specimens; (Positive NAA results in a smear negative specimens are considered helpful in flagging potential cases, but require additional supporting evidence, as in low prevalence populations,  false positives occur frequently.
10. 74 5.2 Clarification of smear step at the top, subsequently a)...(e.g. preparation of direct smears from unconcentrated sputum for acid fast staining).b)  Please consider suggesting or expressing preference for Class II for biologic safety cabinet and for centrifuge cups, rather than I or II as equivalent. 
11. 92 G.5.3a Addition of timing of specimens ...the HCW ....should return to work when they have had three negative AFB sputum smear results collected as first morning samples.  (Sensitivity of q. 8 hour sputum [or mixed sputum and saliva] samples seems unnecessarily risky in this setting.)
12. 110-112 K.2 Employee health It will be important in the introductory paragraph and at several locations in the body of  K.2 to emphasize not only the HCW’s fit testing of HEPA filter protection devices, but also the key requirement that the HCW have the required physical assessment of whether they are candidates for these devices.  Those with cardiac and/or certain respiratory ones should use positive flow devices.