New York, Feb 28 (IANS): Antibiotic azithromycin does not prevent recurrent wheezing among infants hospitalised with respiratory syncytial virus (RSV), rather may prove to be harmful, researchers warned.

Azithromycin is known to have anti-inflammatory properties that can be beneficial in some chronic lung diseases, such as cystic fibrosis.

However, among infants hospitalised with RSV, there was no difference in the amount of wheezing in babies treated with azithromycin versus those who received a placebo, according to researchers at Universities of Washington and Vanderbilt.

"Azithromycin and antibiotics in general have no benefit in preventing recurrent wheeze, and there is a possibility they are harmful," said first author Avraham Beigelman, Associate Professor of paediatrics at Washington's School of Medicine.

The findings were presented at the annual meeting of the American Academy of Allergy, Asthma & Immunology in Phoenix and also published in The New England Journal of Medicine - Evidence.

In infants and young children, RSV can cause bronchiolitis, an infection of the small airways in the lungs.

Nearly all children contract RSV at some point in early childhood, and a small percentage develop bronchiolitis severe enough to be hospitalised. Infants hospitalised with RSV bronchiolitis are at an increased risk of developing asthma by age 7.

The trial confirmed, as anticipated, that azithromycin lowers a marker of airway inflammation called IL-8.

Infants treated with azithromycin had lower levels of IL-8 in their noses than infants who received a placebo, confirming anti-inflammatory effects of azithromycin.

But, azithromycin-treated patients did not have reduced risk of developing recurrent wheezing compared with the placebo group.

While the difference did not reach statistical significance, the data actually leaned toward azithromycin increasing risk of wheezing, with 47 per cent of patients who had received azithromycin experiencing recurrent wheezing versus 36 per cent of the placebo group. Recurrent wheezing was defined as three episodes of wheezing during the two to four years of follow up.

"There may be an increase in risk of recurrent wheezing with any antibiotic use," Beigelman said.

He added that the findings are important and must be communicated to pediatricians, "since antibiotics are frequently given to patients with RSV bronchiolitis despite the fact that this practice is not supported by clinical guidelines".