Rugby players who share towels, razors or even ice baths are at risk of passing on serious skin infections, Public Health England experts warn.
An investigation at a Midlands rugby club found the PVL-MSSA bug had spread between players, giving rise to boils, abscesses and carbuncles.
And in serious cases, the infection can lead to life-threatening illness and cause skin and tissues to die.
Doctors have urged players to indulge in less sharing and better hygiene.
The condition is caused by a strain of bacteria, known as methicillin-sensitive Staphylococcus aureus, that produces a toxin called Panton-Valentine leukocidin.
Public Health England investigators examined a cluster of suspected infections at the same rugby team between August 2013 and February 2014.
They found four cases of the infection, having screened about 60 members.
And their tests revealed an identical strain of bacteria was responsible for all four infections, suggesting the bug was being transmitted between people.