Each year, an estimated 2 million patients acquire an infection in a U.S. hospital. Accounting for half of the complications associated with hospitalizations, these infections cost the economy more than $4.5 billion annually.
As germs become increasingly resistant to drugs and therefore harder to fight, prevention of infections becomes ever-more important. A new study points out one reason why this has proved so difficult. Infective microbes can linger for unexpectedly long periods on dry surfaces, such as fabrics and plastics.
Alice N. Neely of Shriners Hospitals for Children in Cincinnati and Mary M. Orloff of the University of Cincinnati College of Medicine recently collected 11 species of fungi from wounds and hospital surfaces. In the lab, they nurtured the microbes, which can cause disease in people with weak immune systems.
When populations of an isolated fungus had grown to high numbers, the researchers mixed them into a liquid and placed drops onto a range of materials found in hospitals. These included the pure cotton used in lab coats and toweling, 100-percent-synthetic fabrics used in privacy curtains and garments, the cotton-polyester blends typical of scrub suits and nursing outfits, and plastics from splash aprons and computer-keyboard covers.
Every day for a month, the researchers tested samples of the dry fabrics and plastics for live fungi. In the September Journal of Clinical Microbiology, the team reports that all the microbes could survive at least a day on most of the materials tested. Six fungi–a Candida, several species of Aspergillus, and a Fusarium–survived the full 30 days on most if not all of the materials.
In two related studies published last year, Neely’s team reported similar findings for disease-causing bacteria–including 3-month survival on fabrics and plastics by eight strains of Enterococci and Staphylococci that are resistant to widely used antibiotics.
Collectively, the studies show that microbes tend to survive longest on plastics, Neely told Science News.
Her team’s systematic investigations show that “microbes can last far longer on [dry] surfaces than people had given them credit for,” notes Barry M. Farr of the University of Virginia Hospital in Charlottesville.
While finding that these materials might be reservoirs of fungal pathogens is important, says Farr, “[Neely’s] data on antibiotic-resistant Enterococci and Staphylococci are even more disturbing.” These germs are “two of the biggest problem pathogens in hospital infections,” he notes.
To transfer the microbes, something has to touch them. That’s why Farr is especially concerned about contamination of privacy curtains and clothes. Nurses and physicians may grab curtains or brush against them repeatedly–and then by shaking a patient’s hand, touching a lunch tray, or changing bedding, deliver the germs they’ve picked up.
Hospital staff must assume that all surfaces harbor germs, Farr says, and see that they’re cleaned frequently.