RESUMEN
Corona virus disease 2019 (COVID-19), which broke out in Wuhan, HuBei in December, 2019, spread around the country in a short term. Some infected patients suffered from severe acute respiratory syndrome. It has become a major public health event of international concern. COVID-19 patients are the main source of transmission and most people get infection easily, so the current main prevention method is interrupting the pathway of transmission. The dental treatments are very special because these operations produce substantial aerosols and lead a high risk of cross-infection, which brings challenge for epidemic prevention and control. In this paper, the characteristics of aerosols and prevention methods of aerosol transmission in dental clinics are mainly discussed.
RESUMEN
<p><b>OBJECTIVE</b>To study the changes of growth and biofilm formation capability of Enterococcus faecalis (Ef) in different stress conditions.</p><p><b>METHODS</b>The changes of growth of Ef in stress conditions were observed by measuring the A600 value with ultraviolet spectrophotometer. Ef was incubated on glass slide in stress conditions, biofilm formation capability of cells was investigated by colony-forming unit (CFU) counting of the culturable bacteria and fluorescence confocal laser scanning microscopy.</p><p><b>RESULTS</b>Ef couldn't growth under the conditions of 2%, 5%NaClO, pH = 11 and 12, the A600 value was unchanged in 96 hours. But the growth curve changed at different levels in other stress conditions: under 1%NaClO, the A600 value peaked at 1.461 at 16 hour (the peaked level was 1.238 at 6 hours in control group) ; under 0,0.05%,0.15% glucose, it peaked at 0.645,0.890, 1.173, respectively, at 6 hour (it was maximized to 1.195 at 6 hours in control group); the A600 value peaked at 1.704 at 6 hours at pH = 9 and 1.225 at 10 hours at pH = 10 (the peak level was 1.732 at 6 hours at pH = 7) . Biofilm assay showed that Ef were able to form biofilm in these stress conditions except 5%NaClO and pH = 12.</p><p><b>CONCLUSIONS</b>Ef could growth and form biofilms in energy starvation, low concentrations of sodium hypochlorite and weak alkaline stress.</p>