Spreading a Durable Protective Layer of Quaternary Ammonium Agents on an N95 Respirator for Predecontamination of Airborne Mycobacterium tuberculosis and Viruses Using Mycobacterium smegmatis and Bacteriophage MS2 as Models

Tuberculosis (TB) and coronavirus disease 2019 (COVID-19), caused by Mycobacterium tuberculosis (MTB) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), respectively, are serious public health issues. N95 respirators are commonly used to protect people from infections in high-risk environments. Consequently, we used Mycobacterium smegmatis and bacteriophage MS2 as MTB and SARS-CoV-2 surrogates to evaluate the ability of a quaternary ammonium agent (QAA) coating on the surface of new N95 respirators to reduce the microbial burden upon aerosol exposure. Regarding the burden (105 CFU (or PFU)/m3) of M. smegmatis and MS2 phage that settled onto the respirator surface, the QAA yielded average reduction efficiencies ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi mathvariant="bold-italic">R</a:mi> <a:mi>%</a:mi> </a:math> ) of 92.4% and 99.8%, respectively. In addition, the antimicrobial activity of the coated respirator was maintained for one week. For bioaerosols that contacted the respirator (105 CFU (or PFU)/m3), the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" id="M2"> <d:mi mathvariant="bold-italic">R</d:mi> <d:mi>%</d:mi> </d:math> of the QAA was 90.7% for M. smegmatis and 94.4% for MS2 phage on the outermost layer of the respirator. Moreover, filtration efficiencies between a QAA-coated respirator and an untreated respirator were not significantly altered ( <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M3"> <g:mi mathvariant="bold-italic">p</g:mi> <g:mo>=</g:mo> <g:mn mathvariant="bold">0.332</g:mn> </g:math> ). These results demonstrate that this QAA product has a durable antimicrobial activity and could reduce the MTB and SARS-CoV-2 concentrations on the N95 respirator surface. However, it is recommended that such a coating respirator not be worn for more than 4 hours based on hemolysis assay results.