Notes From the Field

Mycobacterium chelonae Eye Infections Associated With Humidifier Use in an Outpatient LASIK Clinic — Ohio, 2015

Chris Edens, PhD; Lauren Liebich, MPH; Alison Laufer Halpin, PhD; Heather Moulton-Meissner, PhD; Samantha Eitniear, MPH-VPH; Eric Zgodzinski, MPH; Larry Vasko, MPH; David Grossman, MD; Joseph F. Perz, DrPH; Marika C. Mohr, MS


Morbidity and Mortality Weekly Report. 2015;64(41):1177 

Laser-assisted in situ keratomileusis (LASIK) eye surgery is increasingly common, with approximately 600,000 procedures performed each year in the United States.[1] LASIK eye surgery is typically performed in an outpatient setting and involves the use of a machine-guided laser to reshape the lens of the eye to correct vision irregularities.[2] Clinic A is an ambulatory surgery center that performs this procedure on 1 day each month. On February 5, 2015, the Toledo-Lucas County Health Department (TLCHD) in Ohio was notified of eye infections in two of the six patients who had undergone LASIK procedures at clinic A on January 9, 2015. The two patients experienced eye pain after the procedures and received diagnoses of infection with Mycobacterium chelonae, an environmental organism found in soil and water.

TLCHD staff visited clinic A on February 12, 2015, to review procedures associated with LASIK surgery and identify possible routes of transmission. None were immediately identified. Clinic A subsequently performed 18 LASIK procedures on February 13, 2015. Two of these 18 patients experienced eye pain in early March 2015 and were determined to have laboratory-confirmed M. chelonae. These infections were reported to TLCHD, which prompted clinic A to suspend all further LASIK procedures.

Discussions between CDC, TLCHD, and the Ohio Department of Public Health focused on opportunities for water contamination during the procedures. Although TLCHD staff reported that they did not observe obvious lapses in medication preparation or hand hygiene, they did note that clinic A used two humidifiers to maintain the 40%–50% relative humidity recommended by the manufacturer of the laser device used in the LASIK procedures.[3] These cold air, reservoir style, retail humidifiers were filled with tap water and located in the operating room close to where patients were situated during the procedures. Both humidifiers contained an internal reservoir that held water during use. One of these devices used an ultrasonic nebulizer to produce a mist, whereas the other passed dry inlet air over a saturated wick. The misting humidifier had been purchased in December 2014, and the evaporative device had been in use for multiple years. CDC recommended collecting environmental samples throughout the operating room, including from the water reservoir and air output vents on each of the humidifiers.

Laboratory testing performed by CDC isolated M. chelonae from the water reservoir of the misting humidifier. Pulsed-field gel electrophoresis results indicated that three of the four patient isolates and the humidifier isolate were indistinguishable; the isolate from the fourth patient was closely related (>95% similarity). After this investigation, clinic A disposed of both humidifiers and upgraded its centralized air handling system to control both temperature and humidity in the operating room environment. No further cases have been reported after the resumption of LASIK procedures in June 2015.

This outbreak was likely caused by the use of a consumer-grade misting humidifier that had been contaminated with M. chelonae. Because of the high level of humidity recommended by the manufacturers of the lasers used in LASIK procedures, it is possible that additional LASIK clinics employ similar humidifier systems. Current American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers/American Society for Healthcare Engineering (ANSI/ASHRAE/ASHE) ventilation guidelines state that humidifiers should be located within air handling units or ductwork, and that steam humidification should be used.[4] Additionally, current CDC environmental infection control guidance states that use of reservoir style humidifiers is not permitted in health care facilities.[5,6] This outbreak highlights the potential risk associated with the use of misting humidifiers in health care settings, and the need for diligent adherence to published recommendations for patient care during all procedures performed in outpatient settings.