The potentially life-threatening bacteria Clostridium difficile can cling to hospital bedsheets even after a thorough washing.

That’s according to a new study by British researchers, published in the journal of Infection Control and Hospital Epidemiology. Investigators believe their findings may provide insight into why flare-ups of the bacteria can occur out of the blue.

“The findings of this study may explain some sporadic outbreaks of C. difficile infections in hospitals from unknown sources,” Katie Laird, Ph.D., lead author of the study and head of the Infectious Disease Research Group, School of Pharmacy, De Montfort University, Leicester, United Kingdom, said in a press release. “However, further research is required in order to establish the true burden of hospital bedsheets in such outbreaks.”

Researchers reached their conclusions by washing C. diff-contaminated cotton sheets at high temperatures using industrial detergent. They found that traces of the bacteria lingered afterward. Plus, traces of the disease were also transferred to uncontaminated sheets. Laid said that future research will explore ways to better remove contaminants from linens in the cleaning process.