By Life's Resource Inc. Testing Laboratories

INTRODUCTION

Properly and consistently hand washing is the single most important and cost-effective procedure in reducing the incidence of hospital acquired infections. The Microorganisms responsible for infectious diseases are transmitted by direct contact and by indirect contact with Infected individuals or with contaminated particles or surfaces. Surfaces, such as door handles, or other inanimate objects that become contaminated with infectious organisms that serve as Fomites. Bacterial, fungal, parasite and viral infections are all known to be associated with exposure to contaminated fomites. Fomites can become contaminated in many ways, including touching with contaminated hands. These contaminated surfaces can, in turn serve as reservoirs of infectious microorganisms for recontaminating washed hands.

In order for fomites to serve as vehicles for infection transmission, the infectious Microorganisms must be able to survive association with the fomite until it can be picked up for transmission to a susceptible individual. Survival of infectious microorganisms or contaminated surfaces depends upon conditions, such as temperature, humidity, and light, but can range from a few hours to many months.

The application of continuously sanitizing devices that employ the principle of ultraviolet light is well known in the reduction of nosocomial infection rate when applied to air decontamination in operating theaters. Ultraviolet light will also effectively kill a very wide range of infectious microorganisms on contaminated surfaces.

The Sanihandles® continuously sanitizing door opener is uniquely designed with sources of Ultraviolet light for the purpose of inactivating microorganisms to which individuals may be Exposed when opening doors in health care facilities and in public places. The purpose of this study was to perform several tests to evaluate the effectiveness of the Sanihandles® for the inactivation of microorganisms. The groups of organisms to be tested included total plate count bacteria, total coliforms, fecal coliforms, Staphylococcus auras and Bacillus subtilis. Studies were also to be performed on continuously sanitizing door openers during field operation in a health care facility.

MATERIALS AND METHODS

Sanihandles® DOOR OPENER
The continuously sanitizing door openers used in these studies were obtained from Sani-Tech International, Lady Lake, Florida. The units shown in Figure 1 were made of a high impact polystyrene material which had a smooth gray finish. The ultraviolet source consisted of two G6T5 9 hot cathode lamps. The 6 watt lamps were rated at an ultraviolet light output at 253.7 nanometers of 11 uw Sec/cm2 at 1 meter. The lamps were 9 inches (22.9 cm) long and has a stated arc length of 5.5 inches (14.0 cm).

LABORATORY STUDIES

Study Organisms

The bacteria used in these studies included Aerobacter aerogenes , Escherichia coli, Bacillus subtilis, Staphylococcus aureus and bacterial contaminants from hands of health care facility personnel. The S. aureus culture was a clinical isolate from a patient at St. Vincent's Medical Center in Toledo, Ohio. The A. aerogenes and E. coli cultures were from cultures used by Analytic & Biological Laboratories, Inc. Garden City, Michigan as part of the U.S. Environmental Protection Agency quality assurance program, and the B. subtilis was originally acquired from the U.S. Army at Ft. Detrick, Maryland for use in sterility testing. These bacterial cultures were grown in trypticase soy broth, trypticase soy agar, or nutrient agar at 35 to 37 degree C.

Bacterial densities were determined by using either the pour plate or spread plate technique for plating samples in appropriate concentrations. A mixture of E. coli and A. aerogenes cultures was used to determine the effects of the continuously sanitizing door opener on the densities of total plate, count bacteria. Individual cultures of A. aerogenes and E. coli were used for total coliform and fecal coliform determinations, respectively. Total plate count bacteria were enumerated on nutrient agar, fecal coliforms on m-FC agar, and total coliforms on violet red bile agar. All cultures were incubated at 35 to 37 degrees C for 24 hours except the E. coli, which was incubated at 44.5 Degree C for 24 hours.

EXPERIMENTAL PROCEDURE

Staphylococcus aureas
Two identical Sanihandles® continuously sanitizing door openers were used in these experiments. One was used as a test unit and the other as the control unit. Both units were washed with 95% ethanol using a sterile swab and, after a 5 minute drying period, were placed in a horizontal position. Bacteria from an agar slant culture were serially diluted in trypticase soy broth. The study was performed by placing 0.05 ml of diluted culture on the front surface of the door openers. Using a sterile glass spreader, the culture suspension was spread over the front surface. After permitting the surface to dry for 5 minutes the ultraviolet light in the test unit was activated for 90 seconds while the light in the control unit remained off. One ml of trypticase soy broth was used to wash each surface and 0.1 ml of each wash suspension was plated on trypticase soy agar using the spread plate technique.

Sanitary Indicator Bacteria
Four square inches of the door opener surface area were marked off and the door openers were decontaminated by swabbing with 95% ethyl alcohol ad exposure to ultraviolet light during as outline above. The surface of a Sanihandles® continuously sanitizing door opener was swabbed with a suspension containing either a mixture of an A. Aerogenes and an E. Coli culture, or, with separate cultures of each organism. These test organisms, which represented total plate count bacteria, total coiform bacteria, or fecal coliform bacteria respectively, were exposed to the ultraviolet light source at varying distances and times in several different experiments. The cultures were exposed at a distance of approximately 2 inches for 60 seconds, at approximately 0.5 inches for 15 seconds and at 8 inches for 15 seconds. Each exposed door opener surface was paired with a second surface inoculated with the same bacterial culture not exposed to the ultraviolet light.

After each trial, both the exposed and unexposed surfaces were swabbed using sterile cotton swabs and the bacterial suspensions were eluted into 4 ml of sterile phosphate buffered water. The suspensions were then assayed using the pour plate technique and incubated as described above.

Bacillus subtilis

Test locations were selected on the front surface of the door opener at 3 and 6 inches from the ultraviolet light. Additional locations were selected on the front surface of the door opener (OT exposed to direct ultraviolet rays) to serve as controls before and after the experiment. Before each experiment, the surface of the door opener was washed with 70% ethanol using sterile gauze pads. After approximately 5 minutes, the surface was wiped dry with another sterile gauze pad and residual ethanol was permitted to evaporate for approximately 5 additional minutes. The surface of the Sanihandles® door opener was inoculated with the bacterial culture at the specified locations using sterile cotton swabs.

After the specified ultraviolet light exposure duration, samples were taken using sterile culture collection system swabs, which were then streaked onto trypticase soy agar plates. After sampling all ultraviolet light-exposed locations, a sample was taken at the unexposed locations. Samples were incubated at 37 Degrees C for 24 hours.

Field Tests
Limited qualitative field tests were performed using Sanihandles® continuously sanitizing door openers installed in a health care facility. After installation on the doors of the soiled linen rooms and a service wing, the door openers remained out of operation until qualitative tests were performed. These door openers were cleaned daily by housekeeping personnel using institutional cleaning solutions both before and during of the continuously sanitizing door openers.

Samples were taken from two door openers of the soiled linen rooms and from one door opener from the service wing using single sterile culture swabs for each location. The swabs were placed in liquid thioglycollate medium and incubated overnight at 35 degrees C. Cultures showing evidence of bacterial growth as determined by observed turbidity were subcultured on 5% sheep blood agar and on EMB agar plates. These cultures were then gram stained.

RESULTS

STAPHYLOCOCCUS AUREUS
Within 90 seconds of exposure to the Sanihandles® continuously sanitizing door opener a clinically isolated strain of S. Aureus was reduced from concentrations of 60,000 colony forming units (cfu)/mL and from greater than 600,000 cfu/mL to undetectable densities. Since these experiments were performed over the entire front portion of the door opener, the actual estimated exposure distance was taken as the average (3 inches) of the entire length. Ultraviolet light exposure levels were also estimated as an average of the entire length of the door opener.

BACILLUS SUBTILIS
In the qualitative tests in which the door opener surface was inoculated directly with an undiluted culture of Bacillus subtilizes organisms. The only reportable culture plates were those of samples taken at a 3 inch distance and 88 second exposure and the paired control samples. Other cultures were not countable due to the growth of spreader organisms. Table 6 three replicates of the tests performed under the 3 inch and 88 second condition of exposure. All three replicate tests showed that the concentrations of bacteria were reduced to undetectable concentrations under this exposure condition

Total coliform bacteria (A. Aerogenes), widely used indicators of sanitary quality, were also shown to be highly sensitive to exposure to inactivation on the Sanihandles®. Table 1 shows that at distances as great as 6 inches and only 15 seconds of exposure was sufficient to reduce the total coliform concentrations to undetectable concentrations.

INDICATOR BACTERIA

TABLE 1. EFFECT OF Sanihandles® ON TOTAL COLIFORM BACTERIA
(AEROBACTER AEROGENES)