The Clinical and Laboratory Standards Institute (CLSI) released an updated edition of its standard Protection of Laboratory Workers From Occupationally Acquired Infections; Approved Guideline—Fourth Edition (M29-A4).

This standard is based on US regulations and provides guidance on reducing or eliminating the risk of transmission of infectious agents in a laboratory setting. This edition of M29 includes specific precautions for preventing the laboratory transmission of microbial infections from patient specimens and contaminated laboratory instruments during all stages of the laboratory path of workflow and updated recommendations for the management of the laboratory biosafety training program, including response to exposure of workers to infectious agents.

This document has been reorganized extensively to provide guidance on standard laboratory precautions and best practices for working safely with infectious patient specimens and biohazardous agents derived from them. This edition of M29 contains new information on a process for assessing the risks associated with procedures performed within a laboratory’s scope of practice that will then guide policy, procedure, and work instruction review as a component of continual improvement. 

In addition to revising sections on the use of personal protective equipment and engineering controls, information on good housekeeping and laboratory disinfection practices; specimen collection, handling, transportation, and storage; and collection and disposal of regulated medical and biological waste has been updated and expanded.

Information on exposure prevention measures is provided in detail in sections on occupational health programs and public health emergency preparedness planning, and guidance on incident and accident response has been enhanced. Finally, this version of M29 includes an almost entirely rewritten section with detailed information on developing and maintaining an effective biosafety training and competency assessment program.

M29-A4 is intended to serve as a reference for laboratory directors, managers, and supervisors who are responsible for the safety of laboratory workers who have the potential for exposure to infectious materials as well as for workers who are responsible for protecting themselves, their coworkers, and their community from laboratory-associated transmission of infectious diseases. 

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