A new study from a leader in airborne disease research indicates that Operating Room HEPA filtration is not a guarantee against nosocomial infection. Dr. Russel Olmstead led a team that looked at airborne contamination inside of the OR environment.

Pilot study reinforces use of portable anteroom HEPA filtration

To prevent perioperative transmission of airborne microorganisms

Washington, DC, May 6, 2008 – Amidst an increase in new tuberculosis cases, researchers have begun investigating the effectiveness of new operating room filtration systems designed to protect staff and patients. According to pilot study findings published in the May issue of the American Journal of Infection Control, a supplemental portable anteroom high-efficiency particulate air (PAS- HEPA) filter unit placed outside operating room suites may prevent secondary transmission of airborne microorganisms like Mycobacterium tuberculosis (M. tuberculosis).

“The rate of decline in newly reported tuberculosis cases in the U.S. has slowed,” said lead study investigator Russell N. Olmsted, MPH, CIC, epidemiologist from Saint Joseph Mercy Hospital in Ann Arbor, MI. “This, coupled with the worldwide emergence of even more drug-resistant tuberculosis, reinforces the need for renewed vigilance and surveillance from healthcare professionals. In particular, study results reinforce the need for measures to optimize air particle removal.”

Olmsted and colleagues compared the efficiency of freestanding HEPA filtration units to a new portable anteroom system (PAS)-HEPA combination unit in removing harmful airborne infectious pathogens. Freestanding HEPA units were evaluated in the operating room, while the PAS-HEPA unit was placed outside over the main operating room door. Both smoke plume and non-infectious particles similar in size to M. tuberculosis were used to mimic movement of airborne pathogens within highly pressured environments.

“We observed interruption of normal patterns of airflow with freestanding HEPA units placed inside the operating room,” said Olmsted, adding that instead of being captured by the air-filtration system, smoke plume traveled upward from the operating room table and into the breathing zone of personnel who might be present during a typical surgical procedure.

“This suggests an increased potential for occupational exposure to airborne microorganisms as well as an unwanted introduction of contaminants into the patient’s open surgical site,” he explained.

In contrast, deployment of the PAS-HEPA combination unit pulled the smoke downward, away from the operating room table and toward the floor and main door. The second phase of the study (which involved simulated microscopic particles) mirrored these observations; within 20 minutes, over 94% of submicron particles were cleared from the operating room.

“The results of Mr. Olmsted’s study reinforce the Centers for Disease Control and Prevention (CDC) 2003 guidelines for environmental infection control as well as 2005 guidelines for preventing the transmission of M. tuberculosis in healthcare settings,” said Janet E. Frain, RN, CIC, CPHQ, CPHRM, APIC 2008 President and Director, Integrated Services, Sutter Medical Center in Sacramento, CA. “These findings should be considered for integration into an overall infection prevention and control program to help ensure both patient and healthcare personnel safety.”

These findings substantiate results we've discovered in our testing of Operating Rooms. Recently we found microbial contamination (including fungi) immediately downstream from HEPA filtration units installed in ORs. The contamination was found one week after the filters were certified for efficiency compliance.
Filters are great for trapping microorganisms, but they do not 'kill'. Eventually filters can become colonized and act as a breeding ground for pathogens. Thinking that you have 100% protection because you have HEPA filtration is a false sense of security.
We suggest a balance between UV and filtration to provide a better strategy for reducing environmental pathogens in critical care areas of your hospital. E-mail us to find out more about a recent study in which VIGILAIR provided better protection than laminar flow for operating suites in a large urban hospital.

Study: MRSA Screening Fails to Lower Infection Rates

A new study published in the Journal of the American Medical Association says that universal MRSA screening upon admission to a hospital may not lead to fewer MRSA infections. The study compared two sets of surgery patients who received services at a Swiss hospital.

One group of more than 10,000 patients were screened for MRSA prior to surgery. If they tested positive for MRSA they were isolated and treated with disinfectant and antibiotics. The control group was of similar size and was not screened. Results from the study show no significant differences in the infection rates between the two groups.

From the Chicago Tribune:

"This is what we've been saying all long," said Kathy Warye, chief executive officer of the Association for Professionals in Infection Control and Epidemiology, a group that opposes efforts to mandate MRSA testing.

While screening patients can be a valuable, it's not a "magic wand" and it's not always the best way to deploy a medical institution's resources, said Dr. Stephen Weber, director of infection control at the University of Chicago Hospitals

Critics of the report's findings say the study may've overlooked some pre-existing MRSA reservoirs:

"Dr. Barry Farr, a MRSA expert, noted the Swiss hospital didn't screen patients on medical wards, who probably served as a reservoir of MRSA infections within the institution and skewed the study's results.

About one-third of surgery patients at the Swiss hospital had surgery before measures could be taken to control potential MRSA infections; that may have contributed to the findings, said Dr. Karen Kaul, chair of molecular pathology at Evanston Northwestern Healthcare."

Responses from both sides (pro and con) augment a central argument in VIGILAIR's infection control (IC) strategy.

• We believe that IC is dynamic and multifaceted
• There is no one strategy to eliminate infection
• There are many reservoirs of infection including patients, healthcare workers and the environment
• A prudent IC policy attacks pathogen reservoirs on several fronts simultaneously; bundling strategies works best

So, Now What?

MRSA screening has resulted in significant benefit for other facilities, notably Scandinavian hospitals that have virtually eliminated nosocomial MRSA infection after implementing 100% screening upon admission. This new study is not enough justification for a wholesale discrediting of MRSA screening. It is, however, more evidence that IC is more like a web than a chain. Breaking one link of transmission rarely does the trick.

Echos in the media

It is encouraging to see response from the press over the recent report on hand washing and infection control. The argument that infection control is dynamic and environmental is being heard in the media, and from APIC! See the recent article from US News and World Reports:

Wringing Our Hands Over Infection Control

February 07, 2008 05:19 PM ET | Avery Comarow |
A number of thoughtful comments arrived concerning my January 23 hand-washing post, about a study showing that a much-increased rate of hand-washing is no guarantee that a hospital's infection rate will budge, let alone dive. A couple of correspondents (notably anesthesiologist-blogger Counting Sheep and hospital-CEO-blogger Paul Levy of "Running a Hospital") contributed thoughts that might prevent a few infections here and there.


The following came as a real letter, if also as an E-mail attachment, from Kathy Warye, another CEO. She runs the Association for Professionals in Infection Control and Epidemiology, whose obvious interest in this subject makes her note very welcome.


"Mr. Comarow makes a critical point that even the single most effective intervention (in this instance, hand hygiene) alone can't solve the problem of healthcare-associated infections. Certainly, even the best hand hygiene compliance only gets us so far.

Lessons learned from our 12,000 members who manage infection prevention programs in healthcare facilities around the world tell us that to reduce the risk of infection and protect people coming into hospitals means adopting a full range of strategies. The first step, from a facility-wide perspective, is conducting a proper risk assessment. Good infection prevention and control professionals don't just know their patients—they know their hospital, they know which areas are at high risk and where there may be hidden reservoirs of bacteria, be it the ER or the OR.


System-wide adoption of proper hand hygiene, contact precautions including use of gloves and gowns, and the "checklist" for device-related care that is receiving so much attention of late are among the tools known to be effective in preventing healthcare-associated infections."

Amen! The single largest source of untreated water in any hospital is its HVAC system. For Critical Care Units aerving the most immune compromised patients, we must eliminate the HVAC as a reservior for pathogens. While VIGILAIR is not a panacea, neither is washing hands. Our technology needs to complement other technologies and institutional efforts for infection control.

Hand washing just one part of infection control, medical experts say

An excellent common sense approach to the hype surrounding hand washing hygiene. This article is excerpted from the Grand Island Independent, a newspaper published in Nebraska:

"Widespread use of antibacterial hand gels has helped make it easier for healthcare workers to comply with hand hygiene policies, which is especially important during cold and flu season. The gels, which have been proven as effective at killing germs as soap and water, are also less drying to the skin an important quality for those who work in the medical field and may cleanse their hands up to 50 times per day. Recent studies and local experience have proven, however, that increasing compliance to hand-washing policies is not always enough to reduce the rates of hospital-acquired infections. A study published by the University of Nebraska Medical Center this month showed that while use of antibacterial hand gels in two UNMC adult intensive care units helped the units increase their hand-washing rate from 38 percent to 70 percent, there was no corresponding reduction in hospital-acquired infections. But a similar experiment at St. Francis Medical Center has had different results. At St. Francis, the use of hand sanitizer and the creation of a hand hygiene improvement committee has nearly doubled the rate of hand-washing policy compliance for the entire hospital, said Laura Mader, St. Francis infection control coordinator. The hospital's current 76 percent compliance rate is above the national average. It has also led to a decrease in St. Francis' incidence of hospital-acquired infections, Mader said. While UNMC and St. Francis had different results in similar experiments, officials from both facilities agree that hand washing, while highly important, is only one component of infection control. "There are many factors that influence the development of hospital-acquired infection," said Dr. Mark Rupp, professor of infectious diseases at UNMC. "It would be naive to think that a single, simple intervention would fix this problem." The lack of a correlation between increased hand hygiene and lower incidence of infections could be attributed to many factors, including UNMC's already low infection rate in the ICU."

Infection Control professionals fight disease transmission on many fronts. While hand washing has drawn much attention, it is merely one weapon in the arsenal. We believe that a comprehensive approach to infection control should include air disinfection, especially in critical care units.

Doctors as terrorists: A potential bio-threat?

All eight people arrested in connection with the recent terror attacks in London and Glasgow are medical professionals employed by the UK’s National Health Service (NHS). Seven of the eight are medical doctors or medical students and the final suspect is a lab technician. This sad chapter casts a cloud over Muslim MDs who are speaking out against the recent violence.

But the attacks also illuminate the concern over the use of biological weapons by extremists. Physicians and those training to become physicians have access research facilities in hospitals and universities. While exotic pathogens such as anthrax and smallpox are difficult to obtain, healthcare professionals may have access to other 2^nd tier agents that can be used as, or refined into, a bio-weapon. The CDC enumerated some of these ‘B & C’ level threats:

Category B

Second highest priority agents include those that

• are moderately easy to disseminate;
• cause moderate morbidity and low mortality; and
• require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance.

Category B agents include

• Coxiella burnetti (Q fever);
• Brucella species (brucellosis);
• Burkholderia mallei (glanders);
• alphaviruses,
• Venezuelan encephalomyelitis,
• eastern and western equine encephalomyelitis;
• ricin toxin from Ricinus communis (castor beans);
• epsilon toxin of Clostridium perfringens; and
• Staphylococcus enterotoxin B.

A subset of List B agents includes pathogens that are food- or waterborne.
These pathogens include but are not limited to

• Salmonella species,
• Shigella dysenteriae,
• Escherichia coli O157:H7,
• Vibrio cholerae, and
• Cryptosporidium parvum.

Category C

Third highest priority agents include emerging pathogens that could be engineered for mass dissemination in the future because of

• availability;
• ease of production and dissemination; and
• potential for high morbidity and mortality and major health impact.

Category C agents include

• Nipah virus,
• hantaviruses,
• tickborne hemorrhagic fever viruses,
• tickborne encephalitis viruses,
• yellow fever, and
• multidrug-resistant tuberculosis.

Could doctors bent on jihad create and release a biological agent? While there are many technical hurdles inhibiting such attacks, physicians are among the few who can overcome these obstacles. The recent attacks in the UK indicate that terrorists have not surmounted the technical barriers to obtain, process and disseminate a biological agent. If they had such a weapon, they probably would’ve used it. The fact remains, however, that terrorist groups can recruit people who are highly educated and highly motivated to use whatever means available to kill Westerners.

Terror organizations have relied on scientists in the past. A Pakistani scientist with an advanced degree in microbiology is reported to have obtained anthrax spores under the guise of legitimate research. Papers uncovered by coalition forces in Afghanistan in December 2001 showed that the scientist corresponded directly to al-Qaeda's No. 2 commander, Ayman al-Zawahiri. Al-Zawahiri is a doctor by training, having worked as a surgeon.

More recent developments are also cause for concern as this NPR story notes:

“But a worrying, almost prophetic, story emerged Wednesday from Baghdad: a Church of England clergyman, Andrew White, who is president for the Foundation of Reconciliation in the Middle East, based in Iraq, said he was at a conference in Amman, Jordan in April when he was taken aside by a Sunni religious leader.

"I listened to him for 40 minutes, and he went on about how they were going to destroy Britons and Americans and how they were going to be doing more in the U.K. and U.S., and he finished by saying 'those who cure you will kill you,'" White said. “

Now is not the time for fear mongering. But we should be aware that terrorists are able to attract and radicalize even the most educated in the community. It’s a reminder that we must remain vigilant on many fronts in order to protect ourselves from threats of terrorists.

APIC’s MRSA Study: a good start

The Association for Professionals in Infections Control (APIC), has just released a comprehensive study that found MRSA rates may be much higher than earlier thought. Results showed that MRSA infection and/or colonization rates are at least 8 times greater than the results of previous studies. You can find the study on APIC’s web site here.

The study is significant because it surveyed a broader spectrum of hospitals and patients than any earlier study. So now that you know the prevalence of MRSA, what to do about it? APIC has some direction there as well. Health care workers can download the Guide to the Elimination of Methicillin-Resistant Staphylococcus aureus (MRSA) Transmission in Hospital Settings. This resource is another good start, although it only devotes 2 pages to environmental transmission of MRSA. A quick check of the text finds 62 mentions of the word ‘contact’, as in ‘contact transmission’. There are zero mentions of the term ‘airborne’, as in ‘airborne transmission’.

Why the omission? Could it be that there is no science to back-up the assertion that MRSA is spread via the air? Perhaps these studies were overlooked:

Significance of Airborne Transmission of Methicillin-Resistant Staphylococcus aureus in an Otolaryngology–Head and Neck Surgery Unit¹
In this 2001 study, Japanese doctors attempted to measure if MRSA could be found in the air of a surgical hospital ward. The rooms of three patients who acquired MRSA after surgery were monitored with air samplers and surface swabbing.
Results:
MRSA was detected in all three rooms in the air and on surfaces. 20% of the MRSA particles were within the respirable range, of less than 4 µm.
From the study:

“Methicillin-resistant S aureus was recirculated among the patients, the air, and the inamimate environments, especially when there was movement in the rooms. Airborne MRSA may play a role in MRSA colonization in the nasal cavity or in respiratory tract MRSA infections. Measures should be taken to prevent the spread of airborne MRSA to control nosocomial MRSA infection in hospitals.”

Reduction in MRSA environmental contamination with a portable HEPA-filtration unit.²

In 2006 microbiology researchers in the UK wanted to know if filtering the air in a hospital would lead to a decrease in MRSA found on horizontal surfaces. Ward rooms housing “…heavy MRSA dispensers…” were supplied with portable HEPA filtration units.
Results:
95% of settle plates placed in the wards showed MRSA contamination. Plates were placed in a variety of locations, mostly along the perimeter of the room. When HEPA filtration was introduced, measurable MRSA decreased between 73%-95%. This study makes a direct link between air and the dispersion of viable MRSA.

From the study:

“Although this cannot replace standard infection control measures (e.g. isolation, hand hygiene, protective clothing and cleaning), it is likely to reduce cross-infection risks significantly and could provide a relatively cost effective method for enhancing MRSA control.”

The relationship between airborne colonization and nosocomial infections in the intensive care unit.³
In 2005 Turkish researchers used more than 900 data points to measure airborne pathogens and the colonization of those pathogens in hospital patients. The study tracked 179 patients and found that MRSA is definitely airborne.
Results:
Researchers proved that MRSA was airborne through the use of air samplers. The two most common airborne pathogens were MRSA and Acinetobacter baumannii. Furthermore, the study says there is a link between the concentration of these airborne pathogens and colonization in patients.
From the study:

“It can be concluded that, total number of airborne viable particles in the critical areas such as operating theatres and intensive care units, seems to be a significant risk factor for the development of nosocomial infections in immuno-compromised patients.”

An outbreak of Serratia marcescens infection in a special-care baby unit of a community hospital in United Arab Emirates: the importance of the air conditioner duct as a nosocomial reservoir.⁴

A deadly outbreak of S. marcescens vexed the staff members of a NICU located in the United Arab Emirates (UAE). In total 36 infants were infected, leading to the death of five babies. Concerned healthcare workers desperately worked to find the source of the outbreak.

Results:

Researchers determined that the reservoir of the deadly pathogen was the air conditioning system that fed the NICU. Despite many typical infection control interventions such as staff education, environmental cultures, isolation of colonized patients, compliance with aggressive infection control measures and recognition of the role of cross contamination the colonization of infants grew. When environmental sampling suggested that contamination was emanating from the air conditioning system, the hospital thoroughly sanitized the system. After this measure the 20 week outbreak ended.

From the study:

“…the growth of serratia from airflow samples suggested that the primary source of
this outbreak was the AC duct.”
“In conclusion, we have documented in this report the results of extensive surveillance and the importance of the AC duct site as a reservoir of nosocomial pathogens in the SCBU of a community hospital. The possibility of airborne transmission in nosocomial spread should not be underestimated.”

Although there is ample evidence that MRSA and other pathogens are transmitted via the air, most infection control measures focus on contact precautions. Data indicate that contact transmission predominates, so the emphasis on contact precautions is warranted.

It is reasonable, however, to also address other environmental contributors to infection. As we’ve learned recently in reducing VAP, a bundling approach yielded impressive infection rate reductions. Bundling recognizes that infection control is multifaceted and requires new thinking and new strategies. Bundling’s success proves that infection control is achieved through a system of evidence based measures.

Instead of thinking about infection control as breaking a single link in the ‘chain of transmission’, consider infection as a web with many avenues of opportunity. One of those avenues, the airborne route, deserves greater attention.

References

1. Significance of Airborne Transmission of Methicillin-Resistant Staphylococcus aureus in an Otolaryngology–Head and Neck Surgery Unit
Teruo Shiomori, MD, PhD; Hiroshi Miyamoto, MD, PhD; Kazumi Makishima, MD, PhD
Arch Otolaryngol Head Neck Surg. 2001;127:644-648.

2. Reduction in MRSA environmental contamination with a portable HEPA-filtration unit
TC Boswell; PC Fox
Journal of Hospital Infection 2006 May;63(1):47-54

3. The relationship between airborne colonization and nosocomial infections in the intensive care unit
G Dürmaz, et al
Mikrobiyol Bul. October 2005 (article in Turkish)

4. An outbreak of Serratia marcescens infection in a special-care baby unit of a community hospital in United Arab Emirates: the importance of the air conditioner duct as a nosocomial reservoir
S. A. Uduman, et al
Journal of Hospital Infection (2002) 52: 175±180