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Acinetobacter and Long-term Acute Care
Long-term acute care hospitals (LTACHs) provide an important segment in the continuum of care for a small population (estimated 2 percent to 3 percent) of acute care patients.1 These patients are medically complex, and are dependent on life support systems such as ventilators, parenteral nutrition, respiratory and cardiac monitoring and dialysis. Typically, we receive our patients as transfers from acute care settings following lengthy stays in critical care units where most receive at least one round of antibiotic therapy. This common history provides a population uniquely susceptible to healthcare-acquired infections (HAIs).2 Consequently, LTACHs commonly treat patients with a variety of multidrug-resistant organisms (MDROs). Keeping the incidence of HAIs below national benchmarks requires a dynamic infectious disease control process and a vigilant staff. One organism that has provided a significant challenge is Acinetobacter.
According to the Centers for Disease Control and Prevention (CDC), Acinetobacter is a group of bacteria commonly found in soil and water. Acinetobacter baumannii accounts for 80 percent of reported infections from the Acinetobacter family. Further, Acinetobacter can be spread by person-to-person contact, contact with environmental surfaces, or by exposure to the organism in the environment. A study conducted in 2004 shows that Acinetobacter is responsible for only 1.5 percent of healthcare-related bloodstream infections, making it a well known but relatively uncommon cause of HAI. While the prevalence is still low compared to other resistant organisms, it is gaining prominence because of its increasing resistance to antibiotics, its environmental resilience, and an increase in the number of clinical cases. When studied in 1973, Acinetobacter was susceptible to most available antibiotics. Multi-drug resistant (MDR) Acinetobacter is currently sensitive to very few antibiotics, most of which are known to be nephrotoxic.
Currently, there are no new antibiotics in final stages of pharmaceutical development to which Acinetobacter is sensitive.
A 2006 study that focused in depth on the inanimate surface survival rates of nosocomial pathogens shows Acinetobacter to have a three to five-month surface survival capability – an environmental resilience that plays a critical role in efforts to reduce transmission.3 This is supported by a 2008 study demonstrating the impact of prior environmental contamination on increasing the risk of acquisition of vancomycin-resistant enterococci (VRE).4 VRE has a similar but shorter survival time on surfaces than Acinetobacter.
Many cases of Acinetobacter can be linked to military personnel traumatically injured in specific geographic areas. This is why the military has a special interest in Acinetobacter.5 During the Vietnam War it was noted to be the most-cultured bacillus in traumatic extremity injuries. In 2004 a study showed a significant increase in Acinetobacter blood infections associated with traumatic injuries in military personnel assigned to Iraq, Kuwait and Afghanistan. While the exact cause has yet to be determined, there has been a significant increase in the number of Acinetobacter cases in hospitals in Europe and the U.S. that treat injured soldiers from these specific theaters. The nosocomial spread to non-military patients treated in the same facilities is an important epidemiologic clue about the mechanism behind the increased incidence of MDR Acinetobacter in various regions of the United States.
The LTACH admitted two Acinetobacter-positive patients in December 2007. These were known infections transferred from ICUs in our service area. The number grew through additional admissions and transmissions until February 2008, when there was a population of six. As the challenge and concern of caring for a significant number of isolation patients increased, active steps were taken to identify and eliminate transmission opportunities.
Identifying an unknown source of HAIs, especially one with the characteristics of Acinetobacter, requires active participation from many departments. As efforts intensified, two focus groups were established. The leadership group, led by our infectious disease physicians, represented the decision-makers from various involved departments, including nursing, respiratory therapy, physical and occupational therapy, housekeeping and maintenance. This group increased in size with the passage of time and was charged with exploring transition possibilities and making process changes based on surveillance, audit, and observational input. Each respective professional discipline evaluated cleaning procedures, shared equipment movement, hand hygiene, PPE audit information and data from various surveillance cultures. Initial observations and negative cultures of reusable equipment allowed many variables to be evaluated, consistently readjusting its focus. Through initial observations, the leadership group was able to identify and eliminate moveable and reusable equipment as the sources of transmission. This was validated through surveillance cultures.
The second group was led by the system’s chief nursing officer and was made up of representatives from employee groups having significant contact with patients in the LTACH. This group consisted of nurses, nursing assistants and respiratory therapists. Their efforts concentrated on changes that would impact the care of isolated patients and identification of deviations from technique that may contribute to transmission. As a result, a number of recommendations were made which improved the process of caring for isolated patients. The most significant contribution came in the form of a Staff Commitment Statement which outlines our commitment to isolated patients and describes the steps staff should take when they observe their peers deviating from (or breaking) isolation protocol. It also describes the process for dealing with accidental or emergent staff contamination. This proactive commitment to peer performance brought to light person-to-person transmission possibilities which could then easily be addressed with anticipated consequence.
Prevalence culturing was a critical tool in determining the sources and methods of colonization and transmission. The following methodology was used during the intense investigatory phases. Patients who were residents during increased Acinetobacter activity were cultured from three sites: sputum, skin/wounds and groin. These patients’ rooms were also cultured in what was determined to be high-touch areas, including call bells, side rails and bedside stands. Additionally, 93 randomly selected environmental cultures were obtained from inanimate objects outside of these patients’ rooms. Finally, in order to provide a complete picture, the entire patient population was cultured from the three aforementioned sites.
The results of the patient cultures identified two additional asymptomatic patients with sputum colonization. It should be noted that all affected patients had tracheostomies, which is a common colonization site given the Acinetobacter preference for a moist environment. Of the 93 random environmental cultures, eight tested positive for Acinetobacter; seven of which were found in rooms of infected patients, and one on a medication cart.
With the discovery of two colonized patients, our Acinetobacter population increased by two to a high of eight in March 2008. The evidence of ongoing transmission resulted in the decision to engage a new technology in room sterilization from STERIS Corporation. The technology creates a dry gas of vaporized hydrogen peroxide which sterilizes all of the exposed surfaces in the room. While this technology has been adapted for other sectors, including governmental and pharmaceutical applications, we provided one of the first applications in a hospital based clinical setting.
The VaproSure® Sterilizer uses U.S. EPA registered Vaprox® Sterilant (EPA#587794) to create a dry sterilant vapor. It is an environmentally friendly, broad-spectrum (sporicidal, bactericidal, fungicidal and virucidal), rapid antimicrobial agent for the sterilization of all pre-cleaned, dry and exposed porous and non-porous surfaces within an enclosed space. The only by-products of the dry sterilization process are water vapor and oxygen. The technology has been used in the pharmaceutical and research industries for more than a decade. It was used primarily for routine sterilization of enclosed environments and surfaces during drug production and laboratory operations. The system is currently in the clinical testing phase in several North American healthcare facilities.
The LTACH unit needing sterilization consisted of 20 patient rooms. Due to our regional demand for ventilator weaning and respiratory management beds, a key factor in establishing our process was the need for rapid and effective sterilization of rooms. In order to determine the effectiveness of our sterilization process, we used six biological as well as six chemical indicators, placed in various locations throughout each room.*
In addition to the VaproSure equipment, four oscillating fans were used to achieve more effective vapor circulation in remote areas such as corners and bathrooms. Sterilization occurs when the desired vapor concentration is maintained for a pre-specified period of time. We chose 250 ppm for 90 minutes to optimize our room turnover rate.
Each room to be sterilized was terminally cleaned by the housekeeping staff before sterilization. Most porous materials were removed from the room. Windows, doors, and vents were sealed to prevent vapor leakage. The sterilizer was controlled and managed using a laptop computer that was placed outside the room. Appropriate warning signs were also placed outside the room before initiating the process.
The VaproSure Sterilizer operates in four stages. The first phase of the process is known as dehumidification. During this phase, dried air is injected into the enclosure and moisture is removed. During the second phase, known as conditioning, the VaproSure system converts Vaprox sterilant into a dry vapor, which is rapidly injected into the room to raise sterilant levels to effective concentrations. During the sterilization phase, the vapor concentration is maintained at the target levels to deliver a sterilization dose. During the final phase, called aeration, the injection of Vaprox sterilant is stopped and the sterilant breaks down into water vapor and oxygen. Aeration continues until sterilant presence is reduced to an acceptable level, or 1 part per million (ppm).
During the conditioning, sterilization and aeration phases in the LTACH, adjacent areas were monitored for leakage using a hand-held H2O2 sensor. Although not required, our hospital policy mandates that a trained, certified operator be in attendance during the first three phases of the process, which typically took four to five hours to complete. Although the VaproSure system can help break down the sterilant on its own, our aeration efforts were accelerated by exhausting the sterilant to the atmosphere through windows opened from outside the first-floor building. ** This allowed the Aeration phase to be completed in approximately seven to eight hours, or approximately half the time it would have taken had the open window method not been used.
To emphasize the impact of porous material on room turnover time, consider that to complete an average uncarpeted room requires approximately 12 hours, whereas a carpeted room requires approximately 30 hours. The next step in the process was to review the chemical indicators for saturation and to place the biological indicators into a tabletop incubator for processing and validation of sterilization.
We discovered that Acinetobacter was very resilient on environmental surfaces and that positive cultures were possible even after usual terminal cleaning. All rooms that were sterilized had cultures that were negative for all organisms. Because of this evidence, we have altered our routine practices to provide for sterilization of rooms that may harbor MDRO post-discharge. Further, our preventive program requires that each room be sterilized at least once a year. Since the beginning of our sterilization process, we have reduced our acquired infection rate to a point below national benchmarks, and have taken our infection control process to a new level of performance.
Cultures of high-touch areas were obtained from the rooms after the terminal cleaning but before the sterilization process, and then again after the sterilization process was completed. Cultures from rooms of patients confirmed Acinetobacter-positive taken after the terminal cleaning consistently tested positive while those taken after the sterilization process came back negative. Room sterilization was able to do what our cleaning techniques could not — eliminate positive cultures of Acinetobacter from environmental surfaces in the treated rooms.
The room-cleaning techniques were critically reviewed and cleaning solutions were sent to an independent lab along with cultures of Acinetobacter stains from our facility. The results indicated that our cleaning solutions were not sufficiently effective against the resident strain of Acinetobacter. We changed our cleaning solutions to a more aggressive agent and saw immediate changes in the room culture profile. Rooms were testing negative at the pre-sterilization phase. We have changed our approach to patients infected or colonized with MDROs as well. Changes in policy include:
1. At-risk patients are cultured on admission and placed in isolation until results are available.
2. All rooms with known Acinetobacter-infected patients, or those with similar profiles, are sterilized with the VaproSure Sterilizer at the time of patient discharge.
3. All new employees go through expanded orientation for caring for patients with MDROs.
4. All new employees sign the staff commitment pledge.
Following our changes in procedure and cleaning products, there have been no new reported transmissions of Acinetobacter. The determination to improve technique, pursue questions, and willingness to try new technology has improved our understanding of how to combat environmentally resilient MDROs.
*Note from the manufacturer: The use of biological indicators is not required when treating rooms at or under 4000 cubic feet with pre-validated application conditions such as 250 ppm (of Vaprox) for 90 minutes.
** Note from the manufacturer: Proper personal protective equipment and a respirator are necessary when entering treated rooms with levels of hydrogen peroxide above OSHA-specified limits.
Linton Sharpnack, RN, BS, MBA, is the chief nursing officer at University Hospitals Extended Care Campus in Cleveland, Ohio. He holds a master of business administration from Case Western Reserve University, Cleveland, Ohio. He received the Kepro Commitment to Quality Star award in 2007.
Lisa Samples, RN, serves as manager of the long-term acute care hospital (LTACH) for University Hospitals Health System, Cleveland, Ohio.
Patricia Sharpnack, RN, BSN, MSN, serves on the nursing faculty at The Breen School of Nursing at Ursuline College in Pepper Pike, Ohio. She is also the faculty advisor to the Student Nurses of Ursuline College (SNUC). Sharpnack is currently a candidate for the Doctor of Nursing Practice at Frances Payne Bolton School of Nursing of Case Western Reserve University in Cleveland, Ohio.
1. Murer C. In abeyance: The status of LTACH. Rehab Management. April 2008. Accessed at: http://www.rehabpub.lcom/issues/articles/2008-04_08.asp.
2. Cunha BA. Acinetobacter. eMedicine. May 8, 2007. Accessed at: http://www.emedicine.com/MED/topic3456.htm.
3 Kramer Axel, et. al. How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. Biomed Central, BMC Infections Diseases. 2006, 6:130. Accessed at: http://www.biomedcentral.com/1471-2334/6/130.
4 Drees Marci, et al. Prior environmental contamination increases the risk of acquisition of vancomycin-resistant enterococci. Clinical Infectious Diseases. 2008; 46:678-85.
5 Scott, PT et al. Acinetobacter baumannii infections among patients at military medical facilities treating injured U.S. service members, 2002-2004. Centers for Disease Control. Morbidity and Mortality Weekly Report, 18 Nov 2007. Accessed at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5345a1.htm.