Reemergence ofMycobacterium chimaerain Heater–Cooler Units despite Intensified Cleaning and Disinfection Protocol

Peter W Schreiber,Maximilian Halbe,Barbara Hasse,Rami Sommerstein,Hugo Sax,Guido V Bloemberg,Dominique Bettex,Christian Rüegg,Stefan P Kuster,Peter M Keller,Francesco Maisano,Philipp Kohler,Cornelia Bayard

doi:10.3201/eid2210.160925

Peter W Schreiber, Maximilian Halbe + Show 11 more

Open Access

https://doi.org/10.3201/eid2210.160925

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Abstract

Invasive Mycobacterium chimaera infections after open-heart surgery have been reported internationally. These devastating infections result from aerosols generated by contaminated heater–cooler units used with extracorporeal circulation during surgery. Despite intensified cleaning and disinfection, surveillance samples from factory-new units acquired during 2014 grew nontuberculous mycobacteria after a median of 174 days.

Highlights

Mycobacterium chimaera is an emerging pathogen causing disastrous infections of heart valve prostheses, vascular grafts, and disseminated infections after openheart surgery [1,2]
Mycobacterial cultures were performed according to standard methods by using the mycobacteria growth indicator tube system (MGIT 960; Becton Dickinson, Sparks, MD, USA) or Middlebrook 7H11 agar plates (BD Difco Mycobacteria 7H11 Agar; Becton Dickinson) that were incubated at 37°C for 7 wks or until positive
Before first use and every 3 months thereafter, a disinfection cycle was performed by adding 200 mL of 3% sodium hypochlorite (Maranon H; Ecolab, Northwich, UK) to the heater–cooler units (HCUs) water tanks filled with filtered tap water (Pall-Aquasafe Water Filter AQ14F1S; Pall, Portsmouth, UK) to a final concentration ≈0.045% sodium hypochlorite in the water tank and circuits

Summary

Cleaning and Disinfection Protocol

Growing evidence supports airborne transmission resulting from aerosolization of M. chimaera from contaminated water tanks of heater–cooler units (HCUs) that are used with extracorporeal circulation during surgery [3,4]. The Study Identification of M. chimaera infection in 6 patients prompted an outbreak investigation at the University Hospital Zurich, a 900-bed tertiary-care hospital in Zurich, Switzerland, that performs ≈700 open-heart surgeries that use extracorporeal circulation per year. Author affiliations: University Hospital Zurich, Zurich, Switzerland NTM growth was recorded after a median of 174 (range 158–358) days in HCU water samples. One of 5 HCUs remained permanently without growth of M. chimaera; 4 grew M. chimaera after a median of 250 (range 158–358) days

Conclusions

Findings

Circuit not specified