Misidentification of Risk Group 3/Security Sensitive Biological Agents by MALDI-TOF MS in Canada: November 2015-October 2017.

Background: Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) is a technology increasingly used in diagnostic identification of microorganisms. However, anecdotal evidence suggests that this technology is associated with misidentification of Risk Group 3 (RG3)/Security Sensitive Biological Agents (SSBA) resulting in exposure risks to laboratory personnel.

Objective: To investigate and characterize incidents related to the use of MALDI-TOF MS in Canada between November 6, 2015, and October 10, 2017.

Methods: Cases were identified from laboratory incident reports in the national Laboratory Incident Notification Canada (LINC) surveillance system. Eligible cases referred directly to MALDI-TOF MS or one of three RG3/SSBA organisms, species, and . A questionnaire was developed to identify potential risk factors leading to the exposure. Reporters from organizations with selected incidents were interviewed using the questionnaire. Data were entered into an Excel spreadsheet and standard descriptive statistical analysis performed to assess common characteristics and identify possible risk factors.

Results: There were eight eligible incidents and a total of 39 laboratory workers were exposed to RG3/SSBA organisms. In five (out of eight) of the incidents, the reporters indicated that their device was equipped with both clinical and research reference libraries. For six incidents where reporters knew the type of library used, only the clinical library was employed at the time of the incident even though both libraries were available in five of these incidents. In all eight cases, the exposure occurred during the sample preparation stage with analyses performed on an open bench and directly from the specimen. And in all eight cases, patient specimens were received without information regarding potential risk.

Conclusion: This first national study characterizing the nature and extent of laboratory incidents involving RG3/SSBA that are related to the use of MALDI-TOF MS identifies risk factors and provides baseline data that can inform mitigation strategies.