Aerosols of mycoplasmas, L forms, and bacteria: comparison of particle size, viability, and lethality of ultraviolet radiation

Abstract

Aerosols of microorganisms were tested for particle size by use of an Andersen sampler. Mycoplasma aerosols had an average count median diameter (CMD) of 2.1 +/- 0.5 mu. Staphylococcus aureus L forms gave an average CMD of 4.6 +/- 1.7 mu; the diphtheroid L form, a CMD of 3.4 +/- 0.3 mu. Escherichia coli had a CMD of 5.4 +/- 2.5 mu; Neisseria sicca, 3.3 +/- 0.5 mu; N. meningitidis, 3.4 +/- 0.2 mu. S. aureus ATCC 6538, the parent strain of the L form, yielded a CMD of 3.9 +/- 1.2 mu. Candida albicans gave an average CMD of 5.9 +/- 1.4 mu. All organisms tested survived aerosolizing and could be recovered in viable form for at least 1 hr. Ultraviolet radiation at 2,537 A destroyed the bacteria and mycoplasmas instantaneously, and destroyed 87% of the L forms of S. aureus, 69% of the diphtheroid L form, and 98% of the C. albicans cells. After irradiation, viable particles of the L form and C. albicans aerosols were consistently larger, indicating that clumping led to survival. Submicron size particles were found in aerosols of all species tested except C. albicans.