Quantifying the effectiveness of ultraviolet-C light at inactivating airborne Mycobacterium abscessus

• Published in: The Journal of hospital infection Vol. 132; pp. 133 - 139
• Main Authors: Nguyen, T.T., He, C., Carter, R., Ballard, E.L., Smith, K., Groth, R., Jaatinen, E., Kidd, T.J., Thomson, R.M., Tay, G., Johnson, G.R., Bell, S.C., Knibbs, L.D.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-02-2023
• Subjects: Air disinfection; Airborne bacteria; Disinfection - methods; Humans; Inactivation rate; Mycobacterium abscessus; Mycobacterium tuberculosis; Respiratory Aerosols and Droplets; Ultraviolet light; Ultraviolet Rays; UV-C radiation; Airborne bacteria; Ultraviolet light; Inactivation rate; Air disinfection; Mycobacterium abscessus; UV-C radiation
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2022.10.008

Mycobacterium abscessus (MABS) group are environmental organisms that can cause infection in people with cystic fibrosis (CF) and other suppurative lung diseases. There is potential for person-to-person airborne transmission of MABS among people with CF attending the same care centre. Ultraviolet light (band C, UV-C) is used for Mycobacterium tuberculosis control indoors; however, no studies have assessed UV-C for airborne MABS.
To determine whether a range of UV-C doses increased the inactivation of airborne MABS, compared with no-UVC conditions.
MABS was generated by a vibrating mesh nebulizer located within a 400 L rotating drum sampler, and then exposed to an array of 265 nm UV-C light-emitting diodes (LED). A six-stage Andersen Cascade Impactor was used to collect aerosols. Standard microbiological protocols were used for enumerating MABS, and these quantified the effectiveness of UV-C doses (in triplicate). UV-C effectiveness was estimated using the difference between inactivation with and without UV-C.
Sixteen tests were performed, with UV-C doses ranging from 276 to 1104 μW s/cm2. Mean (±SD) UV-C effectiveness ranged from 47.1% (±13.4) to 83.6% (±3.3). UV-C led to significantly greater inactivation of MABS (all P-values ≤0.045) than natural decay at all doses assessed. Using an indoor model of the hospital environment, it was estimated that UV-C doses in the range studied here could be safely delivered in clinical settings where patients and staff are present.
This study provides empirical in-vitro evidence that nebulized MABS are susceptible to UV-C inactivation.