The recommendations in this chapter are the minimum requirements needed to limit or reduce risks of infection in laboratories carrying out specific procedures that are considered to have a low risk of spreading TB. Additional measures may be deemed necessary following a site-specific risk assessment.
Low-risk laboratories that follow the minimum biosafety requirements described in this chapter can safely perform certain procedures with sputum specimens, given that the viscous nature of sputum is not prone to generating aerosols when good microbiological techniques are followed. Low risk laboratories can:
- manipulate sputum specimens for direct sputum-smear microscopy;
- manipulate sputum specimens for the Xpert MTB/RIF® assay (Cepheid, Sunnyvale Ca.,USA).
While opening sputum containers and making a direct sputum smear may produce aerosols, the risk of transmission from such procedures is negligible in comparison with aerosols produced by a single unprotected cough. There is little epidemiological evidence that preparing a direct smear is associated with a measurable excess risk of acquiring TB infection.¹⁴ ¹⁵
Note: The collection of sputum specimens from patients should not occur in the laboratory.