2004 OPEN FORUM Abstracts
ULTRASONIC VS. ULTRAVIOLET: WHICH PRODUCES FEWER BACTERIA?
Deborah
Cullen, Ed, RRT, FAARC, Sarah Vinson, BS, CRT, Danielle Kerr, BS,
CRT, Kelly Miller, BS, CRT,
Linda Marler, MS, MT(ASCP)SM Indiana
University, Indianapolis, IN
Background: Home humidifiers can provide beneficial moisture
to the air and
their
patients, but can also become harmful when they spread bacteria that
can
lead
to infection. The purpose of our research was to determine which room
humidifier, the ultraviolet or ultrasonic,
promotes the growth of fewer microorganisms and therefore
would be more hygienic for home use. The ultrasonic humidifier
creates a cool mist by means of ultrasonic sound vibrations. The
ultraviolet humidifier uses the germicidal power of ultraviolet light
to provide humidification.
Method: Six humidifiers, three
ultrasonic humidifiers and three ultraviolet humidifiers were
utilized. Our controls for this evaluation were one of the
ultrasonic humidifiers and one of the ultraviolet humidifiers. These
two humidifiers were filled with tap water but not run. The
remaining four humidifiers were filled,
when necessary, with tap water from the same source and run
continuously Monday through Friday for two weeks to simulate
home use. We measured bacterial
counts in the humidifiers using sterile technique, on days 1 (before
units were turned on), 3, 5, 8, 10, and 12. Each 1 ml sample
was plated on 5% Trypticase Soy Agar with 5% Sheep Blood (BAP),
incubated at 37oC
in an ambient air incubator, and
examined for growth each day for 5 days. Colonies were counted on
each plate and identified by a clinical microbiologist using
standard practices (growth on
various media, Gram stain, and biochemical tests) used in the
clinical laboratory for the identification of routine bacterial and
fungal isolates. It was beyond the scope of this study to use
special culture procedures to isolate fastidious organisms.
Results:Colony counts (per 1 ml)
were as follows:
Day
1 Day 3 Day 5 Day 8 Day 10 Day 12
UV-1 1/ml 0 1 0 0 0
UV-2 0 0 0 0 0 0
UV-3 0 0 0 0 0 2
US-1 58 44 49 96 71 >100
US-2 25 8 2 >100 >100 >100
US-3 8 1 7 18 25 >100
Experience: The ultrasonic humidifier permitted bacterial
growth as compared to
the
ultraviolet humidifiers. The ultraviolet humidifiers limited 99% of
bacteria growth, but on average cost about $50-70 more than the
ultrasonic humidifiers. Respiratory therapists should consider
recommending ultraviolet humidifiers, when appropriate, to patients
and their families. Conclusion: Ultrasonic humidifiers were
highly populated with bacteria in the control as well as the two
other units from Day 1 through Day 12. All ultrasonic humidifiers
tested were harboring bacteria even when just opened from the box.
The ultraviolet humidifiers had little to no bacterial
growth.