Link between childhood exposure to tobacco smoke and Streptococcus pneumoniae

Many of the medical risks associated with smoking, such as cancer, emphysema and heart attacks, are well-known to physicians and the general public.

However, there is new evidence that more children exposed to tobacco smoke carry Streptococcus pneumoniae than children without smoking exposure, according to an article in Clinical Infectious Diseases.

S. pneumoniae often exists in the nose and throat, and children are more likely than adults to carry it. If the bacteria, also called pneumococci, grow out of control, infection can result in minor illnesses like ear infections or lead to more serious diseases like sinusitis, pneumonia and meningitis.

Researchers in Israel conducted a surveillance study of more than 200 young children and their mothers. They swabbed the noses and throats of the subjects to determine bacterial carriage rates, and then analyzed the data based on the children's and mothers' exposure to smoking. Seventy-six percent of the children exposed to tobacco smoke carried pneumococci, compared to 60 percent of those not exposed. Exposed children were also more likely than non-exposed children to carry pneumococcal serotypes responsible for most of the invasive S. pneumoniae disease. In the mothers, differences were also noted--32 percent of mothers who smoked carried S. pneumoniae, compared with 15 percent of mothers who were exposed to smoking and 12 percent of mothers not exposed to smoking.

Higher carriage rates of bacteria can translate to higher rates of infection, according to lead author David Greenberg, MD. "Since carriage in the nose is the first step in causing disease, the increased rate of carriage suggests more frequent occurrence of the disease. Indeed, active and passive smoking are associated with increased rate of respiratory infectious diseases," Dr. Greenberg said.

The researchers hope their data will persuade parents to quit smoking, particularly around children. "Smoking parents, especially smoking mothers (or the parent spending the most time with the child) jeopardize their children's health" by putting them at higher risk for invasive and respiratory infections, Dr. Greenberg said. "This should definitely encourage the parents not to smoke in the presence of their child, especially if this child has predisposing factors such as asthma."

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