A new study reveals that biofilms in washing machines may contain potential pathogens and antibiotic resistance genes, posing possible risks for laundering healthcare workers’ uniforms at home.

Washing healthcare uniforms at home could be inadvertently aiding the spread of antibiotic-resistant infections within hospitals, according to new research led by Katie Laird of De Montfort University. The findings were recently published in the open-access journal PLOS One.

Hospital-acquired infections remain a serious public health issue, partly because they often involve bacteria resistant to antibiotics. While many healthcare professionals launder their uniforms at home using conventional washing machines, previous research has shown that clothing can serve as a vehicle for bacterial transmission. This raises concerns about whether home washing methods are sufficient to eliminate harmful pathogens.

In this new study, researchers tested six different models of domestic washing machines by laundering fabric swatches contaminated with bacteria under both rapid and standard hot-water cycles. Results showed that 50% of the machines failed to effectively disinfect the samples during the rapid cycle. Alarmingly, one-third also failed to fully decontaminate the fabrics even during the longer, standard wash cycle.

Pre and Post Domestic Laundering of Bacteria Contaminated Textiles
Pre- and post-domestic laundering of bacteria-contaminated textiles. Credit: Dr. Caroline Cayrou, CC-BY 4.0

Dangerous Biofilms and Hidden Resistance

The team also sampled biofilms from inside 12 washing machines. DNA sequencing revealed the presence of potentially pathogenic bacteria and antibiotic resistance genes. Investigations also showed that bacteria can develop resistance to domestic detergent, which also increased their resistance to certain antibiotics.

Together, the findings suggest that many home washing machines may be insufficient for decontaminating healthcare worker uniforms, and may be contributing to the spread of hospital-acquired infections and antibiotic resistance. The researchers propose that the laundering guidelines given to healthcare workers should be revised to ensure that home washing machines are cleaning effectively. Alternatively, healthcare facilities could use on-site industrial machines to launder uniforms to improve patient safety and control the spread of antibiotic-resistant pathogens.

The authors add: “Our research shows that domestic washing machines often fail to disinfect textiles, allowing antibiotic-resistant bacteria to survive. If we’re serious about transmission of infectious disease via textiles and tackling antimicrobial resistance, we must rethink how we launder what our healthcare workers wear.”

Reference: “Domestic laundering of healthcare textiles: Disinfection efficacy and risks of antibiotic resistance transmission” by Caroline Cayrou, Katie Silver, Lucy Owen, Jake Dunlop and Katie Laird, 30 April 2025, PLOS ONE.
DOI: 10.1371/journal.pone.0321467

This research was funded by De Montfort University and the Textile Services Association.

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