Montelukast Increases Bacterial Sinusitis in Mice

Treatment leads to significantly higher bacterial counts in allergic and infected mice

THURSDAY, Sept. 28 (HealthDay News) -- Although montelukast reduces symptoms of allergic rhinitis in mice, it is also associated with increased bacterial growth, according to a report published in the September issue of the Annals of Allergy, Asthma & Immunology.

Paneez Khoury, M.D., of the University of Chicago, and colleagues tested the effects of montelukast on allergic inflammation in mice that were ovalbumin sensitized and ovalbumin challenged. They also tested the drug's effects on mice with nasal inoculation of Streptococcus pneumoniae and in mice that were allergic and infected with the bacteria.

The researchers found that infected mice treated with montelukast tended to have increased bacterial counts from nasal lavage compared to untreated mice, and that treated mice that were allergic and infected had significantly higher bacterial counts. Treated mice also had significantly decreased eosinophil and T-lymphocyte counts.

"The clinical significance of our findings is unknown," the authors write. "Montelukast has been given to millions of patients with asthma and allergic rhinitis, and there has been no reported increase in bacterial infections. However, because most upper respiratory tract bacterial infections are low grade and more than 60 percent of acute episodes of bacterial rhinosinusitis will respond to placebo treatment, it may be difficult to detect an increased prevalence of infections without a careful search."

Funding for this study was provided by a grant from Merck.

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