MRSA and the Application of Germicidal Ultraviolet Light
By D.L. Witham, VP Technology
UltraViolet Devices, Inc – Valencia, California

Recently there has been much coverage in the news about MRSA and the diseases it can cause.  Some people maybe already familiar with MRSA, however the following will give a brief summary regarding this pathogen and more importantly how it will react to the application of UV Germicidal Irradiation (UVGI).

 

What is MSRA?

 

MRSA is a strain of a bacterium called Staphylococcus aureus.  This particular strain is called Methicillin-resistant Staphylococcus aureus (MRSA).  Staphylococcus aureus is found in the noses and on the skin of many healthy people.  Healthy people may be colonized by the bacteria in the nose, skin and even in wounds without becoming ill.  Other patients, particularly immuno-compromised patients, may become ill from the bacteria. Infections seem to most often occur in hospitals where patients have had surgery or other treatments and are more susceptible to infection and illness.  It can be common in hospital acquired or nosocomial infections.  Estimates are as high as 1 patient in 10 acquires an infection during their hospital stay.(1)  Normally Staphylococcus aureus can be readily treated with antibiotics.  However, MRSA is a drug-resistant variation of the bacteria. It appears to have become resistant to the antibiotic Methicillin and other common antibiotics.  For this reason it has lately been referred to as the “Super Bug."   It does not cause more severe or different types of illness, it is just more drug resistant than other forms.  The bacteria can cause infections such as impetigo, folliculitis, abscesses and boils.  Deep infections can include endocarditis, meningitis and pneumonia. Symptoms include fever, headache and myalgia.

 

How is it prevented or controlled?

 

Cleanliness and disinfection of surfaces and washing of hands are the current preventative measure.  It appears that it is most commonly transmitted by contact, however it may be transmitted to surfaces when aspirated by patients and there is increasing evidence that many nosocomial infections are transmitted via an airborne route.  In fact, it has been calculated that the airborne route of transmission accounts for approximately 10% of all sporadic cases of nosocomial infections (2).  Coughing and sneezing can disperse large amounts of aerosolized bacteria into the air.  Activities such as bed making can also introduce bacteria into the air.  For these reasons, it is most important that treatment rooms be disinfected between patient visits and good engineering practices be used to keep the air clean.

 

How is MRSA affected by UltraViolet Light?

 

The effectiveness of UVGI, especially UV at a wavelength of 254 nanometers in disinfecting virus, bacteria and fungi has long been known and is well proven.  For many organisms, research has been done and the UV doses required are known and published.  Such is the case for Staphylococcus aureus and therefore MRSA.  It is believed that Micro-organisms are not able to build up an immunity to UV as they do to drugs.  UV irradiation causes physical damage to the DNA of an organism and as the organism cannot reproduce or infect it shortly dies.  As the UV causes physical damage it could be compared to a bullet wound in an animal.  There is no immunity to a bullet.

Review of the literature shows the following doses required for a 99.9% disinfection of Staphylococcus aureus:

 

UVGI disinfection in air: 1,987 micro watt-seconds per square centimeter (3)
UVGI disinfection in water: 6,620 micro watt-seconds per square centimeter (4)

 

These are relatively modest dosage requirements and this means that relatively low levels of UV can be very effective in disinfecting this microbe.

 

UV Tools Available from Altru-V and UVDI

 

All of the UV fixtures from Altru-V® can be utilized effectively against MRSA.  Some examples of the dose or time required for 99.9% disinfection from these fixtures will help demonstrate how effective these tools can be:

 

V-Mod®. V-Mod can be mounted to irradiate surfaces giving from 50 to 1000 microwatt exposure.  If arranged to provide about 500 microwatts, 99.9% disinfection on a surface can be obtained in as little as 4 seconds.

 

V-Flex®. The high output of the V-Flex modules can be mounted in moving air streams to easily provide over 99.9% disinfection.  This could allow all of the air recirculated through the HVAC system of a facility to be disinfected of MRSA and other aerosolized bacteria.

 

Mobile Room Sanitizer.  This portable appliance can be wheeled into a room to disinfect surfaces such as walls and ceilings.  For example, a typical 12 x 12 foot room with a 10’ ceiling would receive a minimum surface irradiation of about 124 microwatts.  This would provide for a 99.9999% surface disinfection of MSRA in less than 5 minutes.

In addition, it has been calculated that droplet nuclei of 2 micrometers, roughly the size of MRSA, could remain suspended in the air for over 4 hours (1).  The Mobile Room Sanitizer will be very effective in disinfecting this room air.

 

Room Air Cleaners. Altru-V offers 1 mobile room air cleaner (NLA90) that is very effective in removing airborne pathogens from a room.  Disinfection levels are excellent and depend upon room size and other ventilation and filtration.

 

For help properly applying UV for control of MRSA, please contact an Altru-V sales representative or you can contact UVDI directly at 1-800-PURE-UVC.

 

References / Notes:
1. Dr. Clive Beggs, “The Use of Engineering Measures To Control Airborne Pathogens in Hospital Buildings”, School of Civil Engineering, University of Leeds, Leeds, UK.
2. Brachman, P.S. Nosocomial infection-airborne or not? Proceedings of the International Conference on Nosocomial Infections. American Hospital Association. (1970). 189-192
3. Dr. W.J. Kowalski, Handbook of Aerobiological Engineering, with references by Braude 1981, Castle 1987, Freeman 1985 , Mitscherlich 1984, Murray 1999 Ryan 1994, Weinstein 1991, Canada2001.
4. Cheferefils, et al., IUVA News Vol.8 No.1 with reference to Chang, et al. 1985.
5. Disinfection predictions by UVDI/Altru-V Proprietary UVGI modeling software.

About UltraViolet Devices, Inc. (UVDI)

UVDI is a leading high volume manufacturer and supplier of UV and molecular filtration products and applications for air, surface and water treatment. Under the ALTRU- V® brand, UVDI markets a full line-up of UV-C products for the commercial and residential HVACR market providing the key benefits of reduced energy consumption, and lower maintenance costs, while delivering cleaner, healthier air. UVDI is one of a few companies in the world that manufactures bonded activated carbon and is the exclusive manufacturer using BPS (Bonded Particulate Structure) technology to produce high quality molecular filtration products. UVDI also provides product design, development and manufacturing for OEM customers that are sold under leading brand names.

Contact:
Dave Witham – VP Technology
+1-661-257-4677
Company:
UltraViolet Devices, Inc.
26145 Technology Dr.
Valencia, CA 91354
+1-877- 787-3882
+1-661-295-8140