1.
MICROBIAL
CONTAMINATION
OF
HEATER-COOLER
UNITS
M. chimaera and
Beyond

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.
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.
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.
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.
Heater-Cooler Unit

7.
Heater-Cooler Circuits

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.
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.
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.
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.
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.
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.
Other NTM Recovered
• M. cookie
• M. palustre
• M. gordonae
• M. timonense
• M. nebraskense
• M. chlorophenolicum (rapid grower)
• M. abscessus/chelonae (rapid grower)

15.
M. chimaera Culture
M. chimaera

16.
Colonies Look Yellow
after Several Weeks

17.
Aging Colonies

18.
M. abscessus/chelonae
and M. gordonae

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.
Uninterpretable
• 97 of 653 water samples were uninterpretable due to
heavy bacterial or fungal overgrowth (15%)

21.
Uninterpretable
• Although we did not culture for fungi, it was present in
many samples

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.
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.
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.
THANK YOU
John Rihs
VP Laboratory Services
jrihs@specialpathogenslab.com