A Comparison of Flavorless Electronic Cigarette-Generated Aerosol and Conventional Cigarette Smoke on the Survival and Growth of Common Oral Commensal <i>Streptococci</i>

• Main Authors: Giancarlo A. Cuadra, Maxwell T. Smith, John M. Nelson, Emma K. Loh, Dominic L. Palazzolo
• Format: Article
• Language: English
• Published: MDPI AG 2019-05-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: ECIG; E-liquid; vaping; smoking; aerosol; <i>streptococci</i>; oral commensal bacteria
• Online Access: https://www.mdpi.com/1660-4601/16/10/1669

<i>Background:</i> The use of electronic cigarettes (ECIG) has become very common. Consequently, critical analysis of the biological effects of ECIG aerosol deserves attention. Flavorless ECIG aerosol is known to comprise fewer harmful constituents than cigarette smoke. Therefore, we hypothesize that aerosol has less immediate effect on the viability of oral commensal <i>streptococci</i> than smoke. <i>Methods:</i> Survival and growth of four strains of commensal <i>streptococci</i> were measured after exposure to flavorless ECIG aerosol &#177; nicotine and smoke. Peristaltic pumps were used to transport aerosol or smoke into chambers containing recently seeded colony-forming units (CFUs) of the oral commensal <i>streptococci</i> on agar plates. Bacterial survival and growth, based on colony counts and sizes, were determined 24 h post-exposure. Additionally, aerosol or smoke were delivered into chambers containing pre-adhered <i>streptococci</i> to plastic coverslips and biofilm formation was determined 24 h post-exposure via scanning electron microscopy. <i>Results:</i> The results suggest that flavorless aerosol &#177; nicotine has a modest effect on bacterial growth both as colonies on agar and as biofilms. In contrast, smoke dramatically decreased bacterial survival and growth in all parameters measured. <i>Conclusion:</i> Unlike cigarette smoke, flavorless ECIG aerosol has only a small effect on the survival and growth of oral commensal <i>streptococci</i>.