Clostridium difficile is a pathogenic bacterium that induces a potentially life-threatening gastrointestinal illness characterized by extreme diarrhea, fever, nausea, and abdominal pain. To spread to a new host, the microbes convert into hardy spores that are introduced back into the environment through fecal matter. From there, the spores easily migrate around via improperly washed hands or contact with any object or surface that has become contaminated with feces, which, as many scientists point out, is pretty much everything. Thanks to their high tolerance for heat, cold, and many types of disinfectant, these spores can easily persist even in regularly cleaned environments.
And now, new findings from the Infectious Disease Research Group of De Montfort University suggest that these spores can persist through the intense laundry regimens designed to remove dangerous microorganisms from hospital linens, meaning that vulnerable individuals could be getting exposed to C. difficile when sheets and other cloth items used by carriers – or those washed in the same machine cycle – are sent back out for reuse.
Reporting their results in the journal Infection Control & Hospital Epidemiology, the authors note that the issue is particularly worrying because, in the UK, most hospitals and care facilities rent linens from independent companies that launder and redistribute to multiple medical sites. Ubiquitous in nature, C. difficile bacteria do not pose much of a threat to most people but can cause serious harm to people with weakened immune systems, those in hospital, and the elderly.
"The findings of this study may explain some sporadic outbreaks of C. difficile infections in hospitals from unknown sources, however, further research is required in order to establish the true burden of hospital bedsheets in such outbreaks," lead author Katie Laird said in a statement.
In a clever series of experiments, Laird and her colleagues first took clean cotton sheets and inoculated them with C. difficile spores. These sheets were then sent through several versions of a laboratory-based cleaning, drying, and pressing cycle designed to mimic the procedure required by the current National Health Service (NHS) healthcare laundry policy, which dictates that linen must be treated with detergents and put through a thermal disinfection cycle at either 65°C (149°F) for at least 10 minutes or at 71°C (160°F) for at least 3 minutes. The team then took naturally contaminated sheets – from C. difficile patients who had been treated in an isolated ward – and sent them to a commercial laundry facility for washing.
A subsequent analysis of the sheets revealed those in both wash categories still harbored high levels of C. difficile, even after a 10-minute 75°C (167°F) treatment with an industrial bleach agent.
“Before laundering, naturally contaminated bed sheets had an average spore load of 51 cfu [colony-forming units] per 25 cm2, and after washing, drying, and finishing, the spore load was 33 cfu per 25 cm2,” the authors wrote. “Both the simulated and in-situ laundering processes failed the microbiological standards of no pathogenic bacteria remaining.”
In addition to only decreasing spore count by about 40 percent, both washing processes transferred spores into the fibers of previously sterile cotton sheets that were included in the same cycles.
According to the group’s press release, they are now working with the UK Textiles Services Association to investigate what laundry methods can successfully remove C. difficile spores.