Nontuberculous Mycobacterium Outbreak at 2 Health Care Facilities Nebraska — 2012–2014

BACKGROUND: Nontuberculous mycobacteria (NTM) are hardy, ubiquitous organisms that are increasingly recognized as pathogens. In August 2013, a midsized Nebraska hospital reported an increase in Mycobacterium chelonae–positive cultures from bronchoalveolar lavage samples. An adjoining facility was also affected. We investigated to determine the outbreak source and implement control measures.

METHODS:  We reviewed data regarding patients with M. chelonae–positive cultures during April 2012–June 2014. In September 2013, we visited the primary facility. We assessed laboratory and bronchoscopy procedures, maintenance, and cleaning. We conducted an environmental survey and sent 32 environmental samples and 27 patient isolates for pulsed-field gel electrophoresis (PFGE) matching at CDC.

RESULTS:  Thirty-five patients had M. chelonae–positive specimens, 2 of whom required treatment. Seventy-one percent of positive specimens were from bronchoalveolar lavages. Samples from internal waterlines supplying automated endoscope reprocessors (AERs), AER tubing, and melted ice from a nonsterile ice machine were M. chelonae–positive. PFGE patterns from the waterlines were indistinguishable or closely related to those of 5 patients. Another 5 patients had indistinguishable or closely related PFGE patterns not matching the environmental samples. The facility purchased bronchoscopes that did not require using the AER for sterilization, stopped using nonsterile ice during procedures, installed aerators on laboratory sinks, and installed bacteriologic water filters at select locations.

CONCLUSIONS: We determined the facilities’ waterlines were the source of M. chelonae; other facilities experiencing an NTM outbreak should consider their waterlines as a possible source. Controlling NTM outbreaks requires a multidisciplinary approach, including risk assessments to identify vulnerable patient care areas, identifying areas of potential NTM growth, strict adherence to infection control procedures, and implementing engineering solutions (e.g., bacteriologic water filters).