Beware well-dressed doctors. Their ties might present a health risk.

A study in New York suggests that doctors' sartorial habits make them carriers of potentially dangerous infections. Researchers found that 47% of ties worn by medical staff at one hospital harboured bacteria and that clinicians were eight times more likely to have bugs in their ties than security staff.

"Studies such as this remind us about what we may bring to our patients' bedside," said Steven Nurkin, of the New York Hospital Medical Centre in Queen's, who presented the findings to the American Society for Microbiology in New Orleans.

The findings called into question whether wearing a tie was in the best interests of patients. "Being well dressed adds to an aura of professionalism and has been correlated with higher patients' confidence.

"Senior physicians and hospital administrators often encourage staff to wear neckties in order to help promote this valuable relationship, but in so doing, they may also be facilitating the spread of infectious organisms.

"While there is no direct evidence to implicate neckties in the transmission of infection to patients, the link between contaminated necktie and the potential for transmission must be considered."

However, there is unlikely to be official advice on the matter in this country. Officials here are far more worried about instilling even more basic hygiene messages in the battle against antibiotic resistant superbugs and other bacteria. This extends to simple reminders for staff to wash their hands, and in some experiments patients are even being encouraged to ask doctors and nurses treating them whether they have done so.

Ties were recently blamed for presenting another medical problem. Eye specialists in New York suggested that men who liked tightly-knotted ties were increasing their risk of contracting glaucoma.