Wednesday, February 24, 2010

cigarettes may cause infection

Wired | The tobacco in cigarettes hosts a bacterial bonanza — literally hundreds of different germs, including those responsible for many human illnesses, a new study finds.

“Nearly every paper that you pick up discussing the health effects of cigarettes starts out with something to the effect that smokers and people exposed to secondhand smoke experience high rates of respiratory infections,” notes Amy Sapkota of the University of Maryland, College Park. The presumption has been that smoking renders people vulnerable to disease by impairing lung function or immunity. And it may well do both.

“But nobody talks about cigarettes as a source of those infections,” she says. Her new data now suggest that’s distinctly possible.

If these germs are alive, something she has not yet confirmed, just handling cigarettes or putting an unlit one to the mouth could be enough to cause an infection.

The idea that tobacco might contain viable germs isn’t just idle conjecture. Several research teams have isolated bacteria from tobacco that they could grow out in petri dishes. Those earlier investigations tended to hunt for — and, when found, attempted to grow — only one or two species of interest, Sapkota says.

What’s novel in her study: She and her colleagues probed for genetic material from any and every bacterium in a cigarette’s tobacco. Under sterile conditions, the researchers opened up cigarettes and then performed a series of tests on the leafy bits. For instance, they isolated all of the ribosomal material and then homed in on its long, species-specific stretches known as 16S regions. These genetic segments were then compared to 16S patches characteristic of known bacterial species.

Sapkota’s team had 16S probes for close to 800 different bacteria and found matches to many hundreds in the four brands of cigarettes screened: Marlboro Red, Camel, Kool Filter Kings and Lucky Strike Original Red. These cigarettes are “among the most commonly smoked brands in Westernized countries and represent three major tobacco companies,” Sapkota notes. All were purchased in Lyon, France, where she was completing her postdoctoral studies.

Among the large number of germs whose DNA laced these cigarettes were: Campylobacter, which can cause food poisoning and Guillain-Barre Syndrome; Clostridium, which causes food poisoning and pneumonias; Corynebacterium, also associated with pneumonias and other diseases; E. coli; Klebsiella, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, all of which are associated not only with pneumonia but also with urinary tract infections; and a number of Staphylococcus species that underlie the most common and serious hospital-associated infections.

Sapkota’s team lists many of these — including the most prevalent bacteria in the tobacco they studied — in a paper published early, online in Environmental Health Perspectives. Fist tap Dale.