Beware of ＂safe＂ e-cigarettes! Studies have reported that its effects on pulmonary pathogens are similar to those of cigarettes.

　　Effects of cigarette smoke (CSE) and electronic cigarette vapor (ECVE) on biofilm. Image source: Respiratory Research

　　In recent years, e-cigarettes are controversial. And a recent report published in the open access journal Respiratory Research may increase the bargaining chip for one side of this debate.

　　Scientists have previously found that smoking-related diseases, such as chronic obstructive pulmonary disease and asthma, are related to some specific bacteria. E-cigarettes have similar effects on these bacteria as traditional cigarettes.

　　Security and attribute doubts

　　E-cigarette is an electronic product that imitates traditional tobacco. It has the same appearance, smoke and taste as cigarettes, and even gives smokers the same feeling.

　　It usually consists of a cigarette tube containing nicotine solution, an evaporation device and a battery. By means of atomization, e-cigarette turns nicotine into steam, and then it is smoked by users.

　　E-cigarettes became all the rage after the efforts of tobacco control in many countries increased. Because it is considered as a safer substitute for traditional tobacco, it is regarded as a reliable "smoking cessation means" because it contains no harmful components such as tar and suspended particles.

　　However, the nature and safety of e-cigarettes have always been controversial. At present, the United States, South Korea and other countries define e-cigarettes as tobacco products, Austria, Canada, Britain and other countries define e-cigarettes as medical products, and Italy, Russia and other countries define them as ordinary consumer goods. At the same time, as early as 2013, German researchers conducted research and analysis on e-cigarettes, and found that e-cigarettes contain a lot of propylene glycol, which may stimulate the respiratory tract and cause some acute symptoms, which may be more harmful than traditional cigarettes. Since then, there have been repeated studies that smoking e-cigarettes for a long time may also lead to dependence on nicotine.

　　Increase the harmfulness of pulmonary pathogenic bacteria

　　The latest report shows that acute lung disease is related to the use of e-cigarettes containing nicotine and traditional cigarettes. The research team from the School of Pharmacy, Queen’s University Belfast, UK, made a detailed comparison of the effects of cigarette smoke and e-cigarette steam on bacteria known to be associated with smoking-related long-term lung disease.

　　The researchers exposed Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa to cigarette smoke extract or e-cigarette vapor extract for culture. The bacteria in the control group were cultured in an environment without cigarette smoke and e-cigarette vapor extract.

　　The researchers found that exposure to cigarette smoke or e-cigarette vapor extract did not seem to have a bad effect on the growth of these bacteria. However, exposure to these extracts increased the biofilm formation of these bacteria, and this effect did not appear in the unexposed control group. Biofilm is an aggregate of one or more types of microorganisms, and it is known that the increase of biofilm is a process of many different types of microbial infections.

　　This discovery may indicate that cigarette smoke and e-cigarette steam will enhance the harmfulness of common pulmonary pathogens and help the formation of stubborn infections.

　　In order to evaluate the harmful degree of bacteria exposed to cigarette smoke or e-cigarette vapor extract — — Or pathogenic changes, the researchers infected the larvae of the great wax moth with bacteria, which are a model organism of human infection and can test the influence of bacterial infection on the survival rate of larvae. However, the survival rate of Cercospora mellifera infected with bacteria exposed to cigarette smoke or e-cigarette steam extract decreased compared with that of the control group.

　　In further experiments, the research team showed that bacteria infected human lung cells under the exposure of cigarette smoke extract or e-cigarette vapor extract, and found that the amount of interleukin -8 (an important factor related to inflammation) secreted by these cells increased.

　　More cigarettes in each bite?

　　Deldri Kilpin, the correspondent of the study, said: "A recurring theme of this study is that the exposure of cigarette smoke and e-cigarette vapor has similar effects on bacterial behavior and pathogenicity. These findings show that e-cigarettes have similar effects on common pulmonary pathogens or cigarettes. "

　　The researchers cautioned that cigarette smoke and e-cigarette vapor extracts used in the experiment were prepared in a similar way, so they may not reflect the difference in nicotine exposure between smoking and smoking e-cigarettes.

　　Kilpin believes: "Compared with traditional smokers, e-cigarette users smoke more and smoke longer in each bite, which may increase nicotine intake. Therefore, our model may underestimate the nicotine exposure of respiratory pathogens in e-cigarette vapor. "

　　In this study, the researchers used a common brand of e-cigarette, which had no added flavor, and bacteria were only exposed once in smoke and steam extracts. They believe that further research is needed to investigate the aroma substances in e-cigarettes and the effects of their long-term exposure. (Reporter Zhang Mengran)