Medical Fabrics: A Reservoir of Pathogenic Bacterium?

Studies tell us that nearly everything in the hospital environment can become a reservoir for pathogenic organisms. Fomites that can carry these pathogens include everything from computer keyboards, pens and phones, to identity badges and lanyards, stethoscopes, PDAs and other medical devices that are mobile and used from patient to patient without being cleaned in between uses.

One fomite that may be under the radar in some hospitals is healthcare fabric, whether it’s uniforms and scrubs, or patient bed linens, furniture and privacy curtains. For example, an item as ubiquitous as a fabric stethoscope cover has been found to be a troublesome fomite. Milam et al. (2001) studied how stethoscope covers are cared for and performed microbiological investigations on 22 covers collected over a three-week period. The researchers suggest that fabric stethoscope covers represent a potential infection control problem because they are used for prolonged periods, are infrequently laundered, and are contaminated with bacteria.

The survival of pathogenic organisms on fabrics found in the healthcare environment is becoming a bigger issue in the fight against healthcare-acquired infections (HAIs). A critical factor for the transmission of microorganisms from person to person or from the environment to a healthcare provider or a patient is the ability of the pathogen to survive on an environmental surface. Numerous studies indicate that bacteria can thrive on medical fabrics. Neely (2000) sought to determine the length of survival of various Gram-negative bacteria on fabrics and plastics commonly used in hospitals. Seven materials were tested: smooth cotton (clothing), cotton terry (towels), 60 percent cotton/40 percent polyester blend (scrub suits and lab coats), polyester (drapes), 75 percent nylon/25 percent spandex (pressure garments), polyvinyl (splash aprons), and polyurethane (keyboard covers). Neely used Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, Acinetobacter species, and Enterobacter species to inoculate material swatches and then assayed them at regular intervals. Survival was dependent on the bacterium, its inoculum size, and the material tested. At 102 microorganisms per swatch, bacteria survived from less than one hour to eight days. At 10(4) to 10(5) bacteria per swatch, survival ranged from two hours to more than 60 days. Neely says her findings emphasize the need for careful disinfection and conscientious contact control procedures in areas that serve immunosuppressed individuals.

In a separate study, Neely and Maley (2000) determined the survival of 22 Gram-positive bacteria (vancomycin-sensitive and -resistant enterococci and methicillin-sensitive and -resistant staphylococci) on five common hospital materials: smooth 100 percent cotton (clothing), 100 percent cotton terry (towels), 60 percent cotton/40 percent polyester blend (scrub suits and lab coats), 100 percent polyester (privacy drapes), and 100 percent polypropylene plastic (splash aprons). Swatches were inoculated with 104 to 105 CFU of a microorganism, assayed daily by placing the swatches in nutritive media, and examining for growth after 48 hours. All isolates survived for at least one day, and some survived for more than 90 days on the various materials.

Neely and Orloff (2001) sought to determine if fabrics and plastics served as reservoirs or fomites for the transmission of fungi species such as Candida albicans, and the ability of some fungi to survive on common hospital items such as privacy curtains, towels, scrub suits, plastic splash aprons and computer keyboard covers. Swatches were inoculated, incubated and tested for fungal survival. The researchers reported that Aspergillus and Mucor survived 26 days; Candida, Fusarium, and Paecilomyces survived for five days. Within the Candida species, C. parapsilosis lived 30 days on all materials, compared to a four-day lifespan of C. albicans, C. tropicalis and C. krusei. The fungi tended to be viable for longer on 100 percent synthetic materials (polyester, spandex, polyethylene and polyurethane) with an average of 19.5 days than on fabrics with some natural fiber content (cotton, terry, and blends) for an average of five days.

Do Bacteria Hitch a Ride on Healthcare Providers’ Clothes?

“You see them everywhere — nurses, doctors and medical technicians in scrubs or white coats,” says Betsy McCaughey, PhD, chairman of the Committee to Reduce Infection Deaths (RID). “They shop in them, take buses and trains in them, go to restaurants in them, and wear them home. What you can’t see on these garments are the bacteria that could kill you.” McCaughey points to the University of Maryland, where 65 percent of medical personnel say they change their lab coats less than once a week, and 15 percent change it less than once a month (Cristoma 2002).

Healthcare uniforms, scrubs and lab coats can be ideal vehicles for the carriage and transmission of bacterium, but one study based on a literature review could not connect uniforms directly to HAIs.

Wilson et al. (2007) conducted a systematic search of national and international guidance, published literature and data on recent advances in laundry technology and processes to determine the role of healthcare workers uniforms’ as reservoirs of pathogenic microorganisms. The researchers found only a small number of relevant studies that provided limited evidence related to the decontamination of uniforms. They found that healthcare workers’ uniforms become progressively contaminated in use with bacteria of low pathogenicity from the wearer and of mixed pathogenicity from the clinical environment and patients. The researchers state that the hypothesis that uniforms/clothing could be a vehicle for the transmission of infections is not supported by existing evidence, and that the laundering process removes or kills microorganisms on fabric. They observe further that there is no robust evidence of a difference in efficacy of decontamination of uniforms/clothing between industrial and domestic laundry processes, or that the home laundering of uniforms provides inadequate decontamination.

Loh et al. (2000) proposed that medical students’ white coats are more likely to be bacteriologically contaminated at points of frequent contact, such as the sleeve and pocket. The researchers identified organisms which were principally skin commensals, including Staphylococcus aureus. The researchers note that the coat’s cleanliness, as perceived by the student, was correlated with bacteriological contamination, yet despite this, a significant proportion of students only laundered their coats occasionally. Loh et al. say this study shows white coats as a potential source of cross-infection and its design should be modified to facilitate handwashing. They add that teaching hospitals should provide freshly laundered coats to medical students.

Physicians’ ties have come under scrutiny as well. Steinlechner et al. (2002) tested the ties of its orthopedic department staff for pathogenic organism carriage and found that all ties were colonized by bacteria that are frequently cultured from swabs taken from discharging wounds of its orthopedic patients. Nurkin (2004) sampled 42 physician neckties and found that 20 of them had one or more pathogenic microorganisms, including 12 that carried Staphylococcus aureus, five with a Gram-negative bacteria, one with Aspergillus and two ties with multiple pathogens.

Long sleeves and the link to the carriage of bacteria was the impetus behind a new “bare below the elbows” rule issued by the British National Health Service, which prohibited physicians from wearing long sleeves and ties. The United States currently has no restrictions on physicians’ apparel, but some experts wonder if the British are on to something. One study conducted at a Connecticut hospital demonstrated that if a HCW entered a room containing a patient with MRSA colonization or infection, the bacteria would be found on the HCW’s clothes approximately 70 percent of the time — even if the HCW did not touch the patient.

Some research indicates that clean uniforms can reduce the spread of infections. St. Mary’s Health Center in St. Louis reduced infections after Cesarean births by more than 50 percent by providing all caregivers with hospital-laundered scrubs as well as requiring them to double-glove. In Connecticut, Stamford Hospital recently banned the wearing of scrubs outside of the hospital, citing a spike in Clostridium difficile infections.

Contaminated Hospital Gowns

Gowns worn by healthcare providers other than surgeons have been implicated in the spread of microbes. Pilonetto (2004) analyzed the microbiota from the uniforms of 31 HCWs in a general intensive care unit. After total viable counts of microorganisms were determined, various parts of gowns were analyzed for microbial contamination at the beginning and end of a work shift. Pathogens were isolated from 48 percent of the gowns; samples from the abdominal region revealed the presence of Staphylococcus aureus, Acinetobacter baumannii, Klebsiela pneumoniae and Serratia rubidae. Pilonetto (2004) also noted that gowns can pick up bacteria from patients and disseminate it within the environment or even to other patients, with increased opportunities for transmission as the HCWs’ shift progressed. Pilonetto (2004) observes, “We found that there is a considerable population of microorganisms in the gowns of medical staff, and this population grows during the work period. This is evident from the rise of bacteria counts from 45.1 CFU/plate (2.2 CFU/cm2) in the first evaluation, to 97.6 CFU/plate (4.9 CFU/cm2) in the second count.” Pilonetto (2004) observes further, “It is known that the more a gown is re-utilized the greater the susceptibility to contamination and, by inference, the less protection afforded to the user and to the patients. The use of reusable cotton gowns should also be analyzed to determine if they are really economical or if the adoption of synthetic, semi-synthetic or even disposable materials would have greater cost-benefit, resulting in a better quality of service for the patient. We believe that a re-education program applied to health professionals would help to diminish bacterial contamination through hospital gowns, especially in the ICUs where the rate of hospital infections is very high.”

Researchers have also discovered that certain bacterium adhere to particular fabrics in distinct ways. Hsieh and Merry (1986) examined the adherence of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli on cotton, polyester and their blends through contact in aqueous suspensions. The researchers discovered that Staph epidermidis adhered to fabrics much more so than Staph aureus, and that the adherence of Staph epidermidis and Staph aureus to fabrics increased as the content of polyester fibers in the fabrics increased. The attachment of E. coli to all fabrics was very low and was not affected by the fiber contents. The total numbers of adherent bacteria on cotton and polyester fabrics were related directly to the concentrations of the bacterial suspensions. The extents of adherence, expressed by the percentage of adherent bacteria from the suspension, however, were independent of the concentration. The length of contact with bacteria was also found to affect the adherence of bacteria on fabrics studied.

Just how bacteria is transferred from fabrics to hands and then to other fabrics again was the focus of study by Sattar et al. (2001), who developed and applied a quantitative protocol for assessing the transfer of bacteria from bleached and undyed fabrics of 100 percent cotton and a 50-50 cotton/polyester blend to fingerpads or other pieces of fabric. Each fabric piece was inoculated with 105 CFU of Staphylococcus aureus. Transfer from fabric to fabric was performed by direct contact using moist and dry fabrics. Transfers from fabrics to fingerpads of adult volunteers were tested using moist, dry and re-moistened pieces of the fabrics, with or withou t friction during the contact. Bacterial transfer from fabrics to moistened fingerpads was also studied. All the transfers were conducted under ambient conditions at an applied pressure of 02 kg cm−2. After the transfer, the fabric pieces were eluted, the eluates spread-plated, along with appropriate controls, on tryptic soy agar and the percentage transfer calculated after the incubation of the plates for 24 hours at 37 degrees C. The researchers concluded that bacterial transfer from moist donor fabrics using recipients with moisture was always higher than that to and from dry ones. Friction increased the level of transfer from fabrics to fingerpads by as much as fivefold. Bacterial transfer from poly/cotton was consistently higher when compared with that from all-cotton material. The researchers say this kind of data could help in the development of better models to assess the role fabrics may play as vehicles for infectious agents.

Privacy Curtains

Fabric can be found everywhere in the hospital, and sometimes the fabric used most often is the least likely to be cleaned regularly. Most notable are privacy curtains. Lambert et al. (2006) point to the presence of multiple-resistant Acinetobacter species on fomite surfaces in the intensive care unit and on bed linen. The researchers point to the curtains surrounding patient beds as the major source of the bacterium. Typing by pulsed field gel electrophoresis demonstrated that the patients’ isolates and those from the environment were indistinguishable. Rigorous infection control measures including increased frequency of cleaning of the environment with hypochlorite and twice-weekly changing of curtains were implemented, along with restriction of meropenem use in the units. Isolation of the multiple-resistant Acinetobacter spp. subsequently diminished and it was not detected over a follow-up period of 18 months. This outbreak also highlights environmental sources, particularly dry fabrics such as curtains, as an important reservoir for dissemination of acinetobacters.

“Much of the failure in breaking the chain of infection likely lies in just the daily pace and pressures placed on healthcare professionals,” says Mark Alan, vice president of InPro Corporation, a manufacturer of the Clickeze privacy systems/soft goods products. “The 1999 Neely-Maley study of infection on fabrics showed that microbes can live in fabrics from one day to as long as 90 days. If you envision a gloved hand pushing aside a privacy curtain, you just saw another link in the chain. Infection control fabrics can help break that chain. The solution, at least in part, is to employ barrier and chemical technologies, and realistic new protocols, to reduce the risk of infection.” Alan adds, “The bottom line is that antimicrobial fabrics can eliminate three possible sites for nosocomial infection – privacy curtains, window treatments and upholstery. From a purely pragmatic, operational aspect, infection-fighting fabrics have the potential to set a new laundering protocol as well.”

Alan explains that the Clickeze antibacterial privacy curtain fabrics incorporate the Aegis Microbe Shield technology to support the elimination of certain pathogens. “Tests of the ShieldTM fabric using the ASTM E 2149-01 test method showed that within 24 hours the material eliminated 99.8 percent or more of the most common microbes classified as the worst types of pathogens (Staph, MRSA,VRE) and 95.7 percent of Clostridium difficile that cause hospital-acquired infections. This same Aegis technology is employed in our Panvelle Stretch™ upholstery fabric. Shield fabrics can also be used as shower curtains in patient bathrooms, which eliminates another possible source of cross-infection.”

Hospital Furniture

Various studies have demonstrated that contaminated environmental surfaces, equipment, and healthcare workers’ hands have been linked to outbreaks of infection or colonization of VRE and Pseudomonas aeruginosa. And now experts believe that furniture upholstery, walls and flooring may act as reservoirs of pathogenic microorganisms.

Lankford et al. (2006) inoculated furniture upholstery, walls and flooring with VRE and Pseudomonas aeruginosa and assessed bioload at 24 hours, 72 hours, and seven days. Inoculated surfaces were cleaned utilizing manufacturers’ recommendations of natural, commercial, or hospital-approved products and methods, and samples were obtained. To assess potential for transmission, volunteers touched VRE-inoculated surfaces and imprinted palms onto contact-impression plates. Twenty-four hours following inoculation, all surfaces had recovery of VRE; 13 of 14 surfaces had Pseudomonas aeruginosa. After cleaning, VRE was recovered from seven surfaces and Pseudomonas aeruginosa from five surfaces.

Noskin et al (2000) assessed survival of VRE on fabric chairs in an attempt to determine the optimal upholstery for the healthcare setting. VRE was identified on three of 10 seat cushions sampled, including two chairs in a room of a patient with known VRE. After performing simulated contamination experiments, all samples were positive at 72 hours and one week after inoculation. Contamination of the upholstery could be prevented by placing a sheet folded four times or a bath blanket folded in half on the seat cushion. The researchers concluded that VRE is capable of prolonged survival on fabric seat cushions and can be transferred to hands, and that environmental surfaces such as chairs may serve as a potential reservoir for nosocomial transmission of VRE. They add that an easily cleanable, nonporous material is the preferred upholstery in hospitals.

 Malik et al. (2006) used feline calicivirus (FCV) to mimic the properties of noroviruses in order to conduct disinfectant efficacy testing on various fabrics and carpets. The researchers applied FCV on fabrics and carpets and allowed it to dry, followed by treatment with a given disinfectant for a defined contact time of one, five and 10 minutes. The surviving virus was then eluted and titrated in Crandell-Reese feline kidney cells to determine virus inactivation. The researchers considered a disinfectant to be effective if it inactivated at least 99 percent of the applied virus. An activated dialdehyde-based product was found to be the most effective disinfectant on all types of fabric and carpet, inactivating more than 99.99 percent of the virus in one to 10 minutes. The researchers discovered that disinfection of carpets was more difficult than the disinfection of fabrics, and that 100 percent polyester was the least amenable to disinfection -- only the activated dialdehyde-based product and a phenolic compound were able to inactivate 99 percent of FCV on 100 percent polyester.

Antimicrobial Fabric Finishes and Other Solutions

Antimicrobial properties built into fabrics is nothing new, but some researchers are encouraging a greater examination of the benefits for the healthcare environment. Chen-Yu et al. (2007) examined whether antibacterial finishes can effectively reduce the presence of bacteria on fabric used for HCWs’ uniforms. The researchers compared the antibacterial property (the percentage of bacterial reduction) of a 65/35 polyester/cotton-blend fabric treated with two commercially available antibacterial agents, AEGIS Microbe Shield (AMS) and polyhexamethylene biguanide (PHMB), before laundering and after five, 10 and 25 laundering cycles, and to determine which agent may be a better choice for HCW uniform fabrics. The researchers found evidence that an antibacterial finish can be an effective way to combat bacterial contamination, and that PHMB-treated fabrics are a viable candidate for use in reusable HCW uniforms up to 25 laundering cycles. They also found that PHMB-treated specimens had a significantly larger reduction against Staphylococcus aureus and Klebsiella pneumoniae before laundering and after repeated laundering cycles than did AMS-treated specimens and non-treated specimens.

A number of antimicrobial finishes for frabrics are currently available on the market, including Foss Manufacturing Co.’s Fosshield® antimicrobial technology and Anovotek, LLC’s AgieneTM treatment for textiles. But if buying antimicrobial fabrics is not in the budget for your hospital, InPro Corp.’s Mark Alan suggests a number of steps facilities can take to avoid fabric-enabled transmission of pathogens: “First, become familiar with the new fabric technologies, and begin a rotational change-out as various floors or wings come due for new privacy curtains.” Alan continues, “Second, explore your protocols ... make sure gloving and handwashing procedures are employed correctly before someone touches a privacy curtain or other in-room fabric. Third, employ a privacy curtain wand. They’re nonporous, easy-to-clean and keep the risk of infection on the surface of the wand, not the fabric.”

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Neely, A. N., Orloff, M. M. (2001). Survival of Some Medically Important Fungi on Hospital Fabrics and Plastics. J. Clin. Microbiol. 39: 3360-3361

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