Smoking kills 'good bacteria' from mouth, facilitates growth of pathogens

There is a new addition to the harmful effects of smoking. As per a scientist of Indian origin, this habit makes your body act against the useful bacteria, making smokers more prone to disease.

The study admits that the mouth of a smoker is much more conducive for the growth of harmful bacteria.

The study further reveals that smokers suffer from higher rates of oral diseases-especially gum disease-than do nonsmokers. These kind of health hazards are challenge for dentists.

"The smoker's mouth kicks out the good bacteria, and the pathogens are called in. So they're allowed to proliferate much more quickly than they would in a non-smoking environment," said Purnima Kumar, assistant professor of periodontology at Ohio State University.

The findings indicate that dentists may have to adminster more aggressive treatment for smokers and would have good reason to advise them to quit the habit, Kumar said.

"A few hours after you're born, bacteria start forming communities called biofilms in your mouth. Your body learns to live with them, because for most people, healthy biofilms keep the bad bacteria away," Kumar explained.

She compared a healthy biofilm to a lush, green lawn of grass. "When you change the dynamics of what goes into the lawn, like too much water or too little fertilizer, you get some of the grass dying, and weeds moving in," she stated.

For smokers, the "weeds" are harmful bacteria that are known to cause disease. In a new study, Kumar's team studied at how these bacterial ecosystems regrow after being destroyed once. This study was conducted on 15 healthy nonsmokers and 15 healthy smokers; the researchers took samples of oral biofilms one, two, four and seven days after specialized cleaning.

The researchers made the observation on two counts. First, they tried to find out which bacteria were present by analyzing DNA signatures found in dental plaque. They also observed whether the subjects' bodies were treating the bacteria as a threat. If so, the swab would show higher levels of cytokines, compounds the body release in response to these infections.

The researchers found that for nonsmokers, bacterial communities maintained a similar balance of species even after wiping it out. Disease-associated bacteria are largely absent, and low levels of cytokines meant that the body is not treating the helpful biofilms as a foreign or threat material.

"By contrast, smokers start getting colonized by pathogens-bacteria that we know are harmful-within 24 hours. It takes longer for smokers to form a stable microbial community, and when they do, it's a pathogen-rich community" Kumar said.

Higher levels of cytokines in smokers suggest that the body is putting a defenses mechanism against this infection. Body’s immune response may be evident in the form of red, swollen gums-called gingivitis-that can develop to the irreversible bone loss of periodontitis.

For smokers, the problem is not confined to fight off harmful bacteria only. The types of cytokines in smokers' gum swabs have been observed to attack even healthy bacteria as threat.

Although the researchers could not figure out the mechanisms behind these results, the team suggests that smoking misleads the normal communication between healthy bacterial communities and their human immune system.

Practically speaking, these findings have clear inferences for patient care, Kumar said.

Infection and Immunity, a journal has published this study.

-with inputs from ANI