Canadian Public Health Laboratory Network (CPHLN) Device Testing Recommendations regarding Non-Tuberculous Mycobacteria (NTM) Contamination in Heater-Cooler Units

Produced by Members of the Canadian Public Health Laboratory Network Device Testing Working Group with consultation from the Infection Prevention and Control Expert Working Group and Health Canada.

Steven Theriault EMCA, HBSc, MSc, PhD (Federal Co‑Chair)Endnote a, Anna Majury PhD DVM (Provincial Co‑Chair)Endnote b, P. Guillaume Poliquin MD, FRCPC, BHScEndnote a, David C. Alexander PhDEndnote c, David Farrell PhD, D(ABMM), FCCMEndnote d, Richard Garceau MD, CSPQ, FRCPcEndnote e, David Haldane MB FRCPCEndnote f, Linda Hoang MSc, DTM&H, FRCPCEndnote g, Frances Jamieson MD, FRCPCEndnote h, Richard Marchand MDEndnote i, Alexis MacKeen BScEndnote j, Dionne Marcino BScEndnote j, Dominik Mertz, MD, MSc.Endnote k, Samir Patel PhD FCCM (D) ABMMEndnote h, Geoffrey Taylor MDEndnote l, Jan Trumble Waddell PhD MSc RDEndnote a, George Zahariadis MD, FRCPC(C)Endnote m, Nathan Zelyas MD, MSc, FRCPC, D(ABMM)Endnote n

The guidance contained in this document should be read in conjunction with relevant federal, provincial, territorial and local legislation, regulations, and policies.

This guidance is based on current, available scientific evidence and is subject to future review as new information becomes available. 

(Last Update: February 09 2017)

Mandate:

A CPHLN Device Testing Working Group (DTWG) has been established and convened to address the emergence of Mycobacterium chimaera as a contaminant in heater-cooler units (HCU), employed during cardiothoracic surgery. This document presents recommendations regarding testing HCU for contamination by M. chimaera, a nontuberculous mycobacterium (NTM) prevalent in the environment, especially water, and a potential opportunistic pathogen.

Background:

Several independent studies have reported postoperative prosthetic valve endocarditis caused by waterborne bacteria, such as Legionella spp. and NTMFootnote 1,Footnote 2,Footnote 3,Footnote 4,Footnote 5. Recently, several emerging cases and clusters of M. chimaera infection have been identified internationallyFootnote 6. The mode of transmission was not deduced until airborne transmission of M. chimaera from HCU was reportedFootnote 1Footnote 7. These HCU are widely used in cardiothoracic surgery as an essential part of extracorporeal circulation, and have been suggested as a source of infectionsFootnote 8, including in CanadaFootnote 9.

A number of HCU in Canada are manufactured by LivaNova PLC (formerly Sorin Group Deutschland GmbH) and referred to as the Stӧckert 3T Heater-Cooler Systems.  Similar HCU are also manufactured by the Maquet Getinge Group, also based in Germany, which are also distributed globally. All clinical cases identified to date are epidemiologically linked to the Stӧckert 3T Heater-Cooler Systems. Currently, only a few cases have been identified in Canada. 

Internationally, genetic evidence indicates that M. chimaera detected in the Stӧckert 3T HCU are clonally related, and also related to strains from affected patients and from M. chimaera found in the environment of the manufacturer in Germany producing the units. This suggests that the contamination comes from a point source that would have occurred at the time of manufacturingFootnote 6,Footnote 10,Footnote 11. Within Canada, some acute care institutions have asked that public health laboratories (PHLs) provide testing for M. chimaera from environmental samples, including water and swabs, collected from the HCU. 

Position Statement:

It is the position of the CPHLN DTWG that testing environmental samples from HCU for M. chimaera is not recommended at this time given the lack of available evidence to suggest its value in determining the risk that individual devices pose.

Laboratory detection of M. chimaera in environmental samples collected from HCU presents numerous challenges, including but not limited to: 

  1. Methods for sample collection, sample processing, and M. chimaera detection in environmental samples from HCU have not been standardized nor validated.
  2. Sensitivity, specificity, limit of detection, and negative and positive predictive value of testing are unknown making it impossible to accurately assess patient risk based on testing for M. chimaera from HCU.
  3.  The patient safety risks associated with removing HCU from service for prolonged periods while waiting for environmental mycobacterial test results, and thereby delaying the initiation of surgical procedures deemed urgent, likely exceed the risk of M. chimaera infection.
  4. The paucity of available data regarding growth and viability of M. chimaera in HCU.
  5. The inability to determine the efficacy of decontamination procedures for HCU through testing.

These recommendations are similar to those of the U.S. Food and Drug Administration (FDA)Footnote 12, and others Footnote 13 and may evolve as new information becomes available.

Acronyms

CPHLN
Canadian Public Health Laboratory Network
DTWG
Device Testing Working Group
FDA
Food and Drug Administration
HCU
Heater Cooler Units
NTM
nontuberculous mycobacteria
PHL
Public Health Laboratory
PHLs
Public Health Laboratories
U.S.
United States of America

References

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