Featured Research

from universities, journals, and other organizations

E-cigarettes may boost resistance of drug-resistant pathogens

Date:
May 19, 2014
Source:
American Thoracic Society (ATS)
Summary:
Despite being touted by their manufacturers as a healthy alternative to cigarettes, e-cigarettes appear in a laboratory study to increase the virulence of drug- resistant and potentially life-threatening bacteria, while decreasing the ability of human cells to kill these bacteria. "The virulence of MRSA is increased by e-cigarette vapor," said the lead investigator. However, she added, the vapor did not make the bacteria as aggressive as cigarette smoke exposure did in parallel studies conducted.

E- cigarette (stock image). "While the answer isn't black and white, our study suggests a response: even if e-cigarettes may not be as bad as tobacco, they still have measurable detrimental effects on health," a researcher concludes.
Credit: JPS / Fotolia

Despite being touted by their manufacturers as a healthy alternative to cigarettes, e-cigarettes appear in a laboratory study to increase the virulence of drug- resistant and potentially life-threatening bacteria, while decreasing the ability of human cells to kill these bacteria

Researchers at the VA San Diego Healthcare System (VASDHS) and the University of California, San Diego (UCSD), tested the effects of e-cigarette vapor on live methicillin-resistant Staphylococcus aureus (MRSA) and human epithelial cells. MRSA commonly colonizes the epithelium of the nasopharynx, where the bacteria and epithelial cells are exposed constantly to inhaled substances such as e-cigarette vapor and cigarette smoke.

"The virulence of MRSA is increased by e-cigarette vapor," said lead investigator Laura E. Crotty Alexander, MD, VA researcher and assistant professor of medicine in pulmonary and critical care at UCSD. Exposure to e-cigarette vapor increased the virulence of the bacteria, helping MRSA escape killing by antimicrobial peptides and macrophages. However, she added, the vapor did not make the bacteria as aggressive as cigarette smoke exposure did in parallel studies her group conducted.

To conduct the e-cigarette vapor experiment, the researchers grew MRSA (USA 300 strain) in culture with vapor concentrations similar to inhalers on the market. They tested first for biochemical changes in the culture known to promote pathogen virulence and then introduced epithelial cell- and alveolar macrophage-killing assays.

The study was presented at the 2014 American Thoracic Society International Conference.

The researchers looked at five factors that contribute to MRSA virulence: growth rate, susceptibility to reactive oxygen species (ROS), surface charge, hydrophobicity and biofilm formation. In particular, e-cigarette vapor led to alterations in surface charge and biofilm formation, which conferred greater resistance to killing by human cells and antibiotics.

Crotty Alexander said that one possible contribution to the increased virulence of MRSA was the rapid change in pH induced by e-cigarette vapor. Exposure changed the pH from 7.4 up to 8.4, making the environment very alkalotic for both bacterial and mammalian cells. This alkalosis stresses the cells, giving them a danger signal, leading to activation of defense mechanisms. The bacteria make their surface more positively charged, to avoid binding by the lethal antimicrobial peptides produced by human innate immune cells. The bacteria also form thicker biofilms, increasing their stickiness and making MRSA less vulnerable to attack.

These changes make MRSA more virulent. However, when MRSA is exposed to regular cigarette smoke, their virulence is even greater. Cigarette smoke induces surface charge changes 10-fold greater than that of e-cigarette exposure, alters hydrophobicity and decreases sensitivity to reactive oxygen species and antimicrobial peptides. In a mouse model of pneumonia, cigarette smoke exposed MRSA had four-times greater survival in the lungs, and killed 30% more mice than control MRSA. E-cigarette vapor exposed MRSA were also more virulent in mice, with a three-fold higher survival.

Unfortunately, while e-cigarette vapor is increasing bacterial virulence, Crotty Alexander has found that the vapor is also decreasing the ability of human epithelial cells to kill pathogens. "As health care professionals, we are always being asked by patients, "Would this be better for me?" Crotty Alexander said. "In the case of smoking e-cigarettes, I hated not having an answer. While the answer isn't black and white, our study suggests a response: even if e-cigarettes may not be as bad as tobacco, they still have measurable detrimental effects on health."


Story Source:

The above story is based on materials provided by American Thoracic Society (ATS). Note: Materials may be edited for content and length.


Cite This Page:

American Thoracic Society (ATS). "E-cigarettes may boost resistance of drug-resistant pathogens." ScienceDaily. ScienceDaily, 19 May 2014. <www.sciencedaily.com/releases/2014/05/140519084557.htm>.
American Thoracic Society (ATS). (2014, May 19). E-cigarettes may boost resistance of drug-resistant pathogens. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2014/05/140519084557.htm
American Thoracic Society (ATS). "E-cigarettes may boost resistance of drug-resistant pathogens." ScienceDaily. www.sciencedaily.com/releases/2014/05/140519084557.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
West Africa Gripped by Deadly Ebola Outbreak

West Africa Gripped by Deadly Ebola Outbreak

AFP (July 28, 2014) The worst-ever outbreak of the deadly Ebola epidemic grips west Africa, killing hundreds. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
Google's Next Frontier: The Human Body

Google's Next Frontier: The Human Body

Newsy (July 27, 2014) Google is collecting genetic and molecular information to paint a picture of the perfectly healthy human. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins