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Microbial Contaminate of Heater-Cooler Units: M. Chimaera and Beyond

Non-tuberculous mycobacteriums (NTM) are small, rod shaped bacilli that are found in the environment and generally cause infection or disease in individuals with preexisting conditions. NTM is a category of mycobacteria, and as the name states, these species do not cause tuberculosis. NTM can cause lymphadenitis, pulmonary disease resembling tuberculosis, skin disease, or disseminated disease. These bacteria have occasionally been isolated from drinking water distribution systems. Disease caused by M. avium complex has been linked to hospital drinking water in HIV patients.

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Microbial Contaminate of Heater-Cooler Units: M. Chimaera and Beyond

  2. 2. Objective • Determine percent positivity of non-tuberculosis mycobacterium, primarily M. chimaera in heater-cooler units (HCU) • Assess colonization of heater-cooler units before and after disinfection
  3. 3. Mycobacterium chimaera • M. chimaera is a slow growing non-tuberculosis mycobacterium • More than 175 species, referred to as NTMs • These bacteria can be found in the soil and water, including potable water • Opportunistic, rarely causes infections in humans • M. chimaera is a relatively new species (2004) • M. chimaera has been linked to infections associated with heater-cooler units
  4. 4. M. chimaera Infections Associated with HCUs • July 2014, Federal Office of Public Health Switzerland issues warning • March 2015, Hugo Sax et al. Clinical Infectious Diseases, first causal evidence to link cases of cardiovascular infections to heater-coolers • June 2015, heater-cooler manufacturer issues Field Safety Notice • September 2015, FDA inspectors visit manufacturer facilities in Germany
  5. 5. M. chimaera Infections Associated with HCDs • In October 2015, a Pennsylvania hospital reported eight patients with M. chimaera infections following cardiac surgery • October 2015, FDA and CDC issue safety communications • December 2015, FDA blocks entry of these units • April 2016, M. chimaera contamination confirmed at the manufacturing site
  6. 6. Heater-Cooler Unit
  7. 7. Heater-Cooler Circuits
  8. 8. What Do We Know About These Infections • Cases of cardiovascular infections have been reported as far back as 2008 • Most of these have occurred in Switzerland, Germany, the Netherlands and the UK • Most infections have been prosthetic valve infections or coronary artery bypass grafts • Difficult to treat, approaching 50% mortality • Patients who had surgery before Sept 2014 may have been at greater risk • Risk for infection is low
  9. 9. Manufacturer Recommended Testing • Heterotrophic Plate Count (HPC) less than 500 cfu/ml • Pseudomonas aeruginosa not detectable in 100 ml • Coliform bacteria not detected in 100 ml • Non-tuberculosis mycobacterium not detected in 100 ml
  10. 10. Laboratory Methods • Performed with standard laboratory methods  Heterotrophic Plate Count (HPC)  Pseudomonas aeruginosa  Coliform bacteria • Non-tuberculosis Mycobacterium  Filter concentration and decontamination with 0.2 M KCl-HCl, pH 2.2  Cultivation: Middlebrook 7H10 and Mitchison 7H11  Incubation at 30°C for 6 weeks  Identification by 16S DNA sequencing
  11. 11. Heater-Cooler Culture Results • Samples from 23 different institutions across 14 states, the District of Columbia, and Canada • 89 different heater-cooler units were tested, 33 of these tested positive for M. chimaera (37%) • Our results show extensive colonization of M. chimaera
  12. 12. Heater-Cooler Culture Results • Four units tested positive with three different species of Mycobacterium • 19 units had two different Mycobacterium species recovered • M. gordonae was isolated 26 of 89 (29%), second most frequently isolated NTM
  13. 13. Heater-Cooler Culture Results • Some units remained positive for Mycobacteria for months • Other units appeared negative but later M. chimaera was detected in low numbers
  14. 14. Other NTM Recovered • M. cookie • M. palustre • M. gordonae • M. timonense • M. nebraskense • M. chlorophenolicum (rapid grower) • M. abscessus/chelonae (rapid grower)
  15. 15. M. chimaera Culture M. chimaera
  16. 16. Colonies Look Yellow after Several Weeks
  17. 17. Aging Colonies
  18. 18. M. abscessus/chelonae and M. gordonae
  19. 19. Heterotrophic Plate Count • Results ranged from <1 cfu/ml to >106 cfu/ml • HPC can be used as a quick test to use to monitor disinfection procedures • HPC results cannot predict the presence of NTM
  20. 20. Uninterpretable • 97 of 653 water samples were uninterpretable due to heavy bacterial or fungal overgrowth (15%)
  21. 21. Uninterpretable • Although we did not culture for fungi, it was present in many samples
  22. 22. Limited Test Results • Zero of 74 HCUs tested positive for coliforms • One of 72 HCUs were positive for Pseudomonas aeruginosa • Four of 22 HCUs were positive for Legionella
  23. 23. Conclusions • M.chimaera contamination was extensive • Heater-cooler units were contaminated with other NTM as well as fungi • Colonization persisted after disinfection • Monitoring for fungi and Legionella is advisable
  24. 24. Infection Control Practitioners Should • Establish regular cleaning, disinfection and maintenance schedules • Monitor and document cleaning, disinfection and maintenance • Provide written instructions on how to collect samples • Follow the culture results • Monitor used and new instruments • Consider risk of infection from any and all heater-cooler units
  25. 25. THANK YOU John Rihs VP Laboratory Services