Nurses' Scrubs Often Contaminated With Harmful Pathogens

Caroline Helwick

October 31, 2016

NEW ORLEANS — Nurses' scrubs can become contaminated with potentially harmful bacteria through direct patient care and through contact with the patient’s environment, according to a molecular analysis of pathogen transmission.

"Our study showed that nurses' clothing becomes contaminated with epidemiologically important organisms in more than 10% of their shifts," said lead investigator Deverick Anderson, MD, associate professor of medicine at the Duke University Medical Center in Durham, North Carolina.

"Much of the published research on the spread of pathogens in healthcare environments is related to the back-and-forth transmission between patients and healthcare workers. We think the environment is a third part of what we call the 'transmission triangle'," he said. "Bugs are spreading from patients to their environment and then to the healthcare worker."

We think the environment is a third part of what we call the 'transmission triangle.'                   Dr Deverick Anderson

In the Antiseptic Scrub Contamination and Transmission (ASCOT) study, Dr Anderson and his team conducted microbiologic and molecular analyses to characterize patterns of pathogen movement. Dr Anderson presented the results here at IDWeek 2016.

In surgical and medical intensive care units (ICUs) at Duke University Hospital, 40 participating nurses wore new scrubs for three consecutive shifts.

Cultures from three scrub sites (sleeve, midriff, and pocket) and from each patient's room (bed, bedrail, supply cart) were taken at the beginning and end of each shift.

Cultures were also obtained from all patients cared for by the nurses (nares, perirectum, integument) on each shift.

The genetic relatedness of pathogens was tested with pulsed-field gel electrophoresis. A potential transmission event occurred if the same pathogen species was identified on the nurse's uniform, on the patient, and/or in the environment. A potential transmission event was confirmed if the identified pathogens were identical.

During the 120 ICU shifts, the 40 nurses cared for 167 patients.

The investigators obtained 2185 cultures from nurses' clothing (mostly scrubs), 455 from patients, and 2919 from patient environments. They looked at three possible patterns of transmission: from patient to nurse, from environment to nurse, and from patient to environment.

During the 120 shifts, there were 39 (33%) potential transmission events and 23 (19%) confirmed transmissions. More than half of the confirmed transmissions (10%) were found on nurses' clothing.

Most of the transmissions went from patient to nurse, and in more than one third of cases, bacteria were transmitted from the environment, not the patient.

"The 10% rate of confirmed transmission is a low number; it's what we confirmed with our microdetection techniques," Dr Anderson reported. But "it's likely higher."

The distribution of the organisms was similar at the three scrub sites sampled. The presence on clothing means that pathogens "are likely present on your hands as well, and then you are likely to transmit," he said.

Harmful Pathogens

Confirmed transmissions of potentially harmful pathogens were observed. Of the 39 potential transmissions, eight were methicillin-resistant Staphylococcus aureus (MRSA), 10 were Acinetobacter baumannii complex, four were vancomycin-resistant Enterococcus species, and three were Klebsiella species.

At baseline, three nurses were colonized with MRSA but none were colonized with the more potentially harmful pathogens. The more harmful bacteria were acquired during the day.

There were no nurse-to-patient or nurse-to-environment transmissions, although such transmissions are clearly possible, said Dr Anderson.

"That's why it's important to track this kind of movement of pathogens," he said. "If you have nurses contaminated with MRSA at the end of the day, and each is taking care of at least two patients in the ICU — and potentially more patients on other units — you have a source of potential transmission of harmful bacteria. Other studies have shown that contamination does pose a risk for clinical issues."

The three take-home messages from this study are that "transmission is a complicated process; these bugs move more frequently than one would think; and healthcare workers should be aware that not only can they become contaminated from patients, simply going into the hospital room poses a risk," Dr Anderson explained.

Infection Control

These findings emphasize the importance of basic hygiene practices (hand washing after all patient encounters, even when gloved), the use of disposable gloves and gowns in some circumstances (although gowns can also be contaminated), and meticulous and regular cleaning of patients' rooms (during their stay, and not just at discharge).

"This complicated study" underscores the need for "the basic infection control principles we have been advocating for decades," said press briefing moderator Kerri Thom, MD, associate professor of epidemiology, public health, and medicine at the University of Maryland School of Medicine in Baltimore.

"Wherever and whenever we look, we seem to find things in the environment. We certainly do not live in a sterile world, and this is a great study to show that," said Dr Thom. "It also emphasizes how little we know about transmission dynamics."

But "we are seeing advances in cleaning technology and better physical cleaning of rooms," said Arjun Srinivasan, MD, from the Centers for Disease Control and Prevention, who serves as IDWeek chair for the Society for Healthcare Epidemiology of America.

"We are also looking at the design of clothing for healthcare workers, new types of scrubs and other clothing impregnated with substances to resist bacteria. There are intriguing things in the future," Dr Srinivasan said.

Dr Anderson, Dr Thom, and Dr Srinivasan have disclosed no relevant financial relationships.

IDWeek 2016: Abstract 943. Presented October 27, 2016.

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