Home washing machines fail to remove important pathogens from textiles

Health care workers who wash their uniforms at home may be unknowingly contributing to the spread of antibiotic-resistant infections in hospitals, according to a new study led by Katie Laird of De Montfort University, published in PLOS One.

Hospital-acquired infections are a major public health concern, in part because they frequently involve antibiotic-resistant bacteria. Many nurses and health care workers clean their uniforms at home in standard washing machines, but some studies have found that bacteria can be transmitted through clothing, raising the question of whether these machines can sufficiently prevent the spread of dangerous microbes.

In the new study, researchers evaluated whether six models of home washing machine successfully decontaminated health care worker uniforms, by washing contaminated fabric swatches in hot water, using a rapid or normal cycle. Half of the machines did not disinfect the clothing during a rapid cycle, while one-third failed to clean sufficiently during the standard cycle.

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 increases their resistance to certain antibiotics.

Together, the findings suggest that many home washing machines may be insufficient for decontaminating health care 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 health care workers should be revised to ensure that home washing machines are cleaning effectively. Alternatively, health care 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 the transmission of infectious disease via textiles and tackling antimicrobial resistance, we must rethink how we launder what our health care workers wear.”