Aspergillosis: A rare case of patient transmission
January 1, 2000 7 minutes read
Aspergillosis: A rare case of patient transmission
Construction dust an ongoing concern
(Editor’s note: We conclude our two-part series on infection control and the environment with an update on aspergillosis. In this story, we report the first case of apparent person-to-person spread of the fungal infection; highlight methods to prevent outbreaks during renovation; and underscore the legal liabilities of even a single case of transmission to a patient.)
Epidemiologists have identified the first reported case of apparent patient-to-patient transmission of Aspergillus fumigatus, a fungus that can cause severe infections in the immune-compromised but usually is traced back to sources in the hospital environment. Indeed, while infection control professionals are increasingly wary of dustborne aspergillosis infections during hospital renovations, there has been less concern that the patho gen could spread from patient to patient.
But the first report of probable person-to-person transmission of Aspergillus was linked to debriding and dressing a severe wound infection, which apparently resulted in aerosolization of spores and airborne transmission to at least one other patient. "This was an extensive wound that covered the entire surface of the patient’s abdomen," says David Pegues, MD, hospital epidemiologist at the University of California at Los Angeles Medical Center. "The results of the cultures that we did — including settle plates with fungal media around the index patient and an air sampling that was performed before and after dressing changes — demonstrated the aerosolization of viable infectious spores did take place. There was no evidence of any significant environmental source in the hospital."
While likely to be a rare event, there are take-home points for infection control professionals to note in preventing any recurrence with similar wound patients, he notes. "Disruptions such as changing the dressing, debriding the wound at the bedside, [or] performing any manipulation of the wound should be minimized," Pegues tells Hospital Infection Control. "If that situation is not practical because of the extent of the wound or the localized infection, we would place such a patient in an air-controlled negative-pressure room to minimize the risk of aerosolization of spores."
Aspergillus species, ubiquitous fungi that occur in soil, water, and decaying vegetation, are primarily a threat to severely immune-compromised patients such as those undergoing bone marrow or organ transplantation. Indeed, the index patient developed deep surgical site and organ space infection with A. fumigatus eight days after a second liver transplant in September 1998, Pegues reported recently in Philadelphia at the annual meeting of the Infectious Disease Society of America.1
The patient was transferred to an open cubicle in an 11-bed transplant intensive care unit, where the abdominal wound was debrided and wet-to-dry dressing changes were performed. Two other patients in the ICU were subsequently diagnosed with invasive pulmonary A. fumigatus infection. A. fumigatus tissue isolates from the index patient and a sputum isolate from one of the two other patients had an identical subtype. The index patient was moved to a private room and portable HEPA-filtration units were placed inside and outside the room. In settle plate testing, colonies of A. fumigatus went from zero prior to a dressing change to as high 34 after. Similarly, air samples outside the room showed A. fumigatus colonies increasing after a dressing change. The index patient was transferred from the ICU to a negative-pressure isolation room, where he died.
Patient was at increased risk
"The point that I would emphasize is that this was a patient who was at profoundly increased risk for developing aspergillosis," Pegues says. "We know it came from somewhere in the environment, as the result of the fact that he had at least four surgeries with a failed liver transplant during that hospital admission and a large open abdominal wound. So a single colony of Aspergillus from the environment could have been the source. As safe as we wish to make the hospital environment, I am not aware of anyone who can remove the risk of aspergillosis entirely. But there did not did appear to be an environmental source to explain the outbreak."
Indeed, most aspergillosis infections and outbreaks are traced to environmental sources, particularly dustborne fungi dispersed during construction and renovation.2 Such outbreaks threaten to increase with rising patient acuity and many hospitals trying to extend the life of aging facilities through renovations and expansions. The Centers for Disease Control and Prevention is updating infection control guidelines for aspergillosis, including recommendations for dust control and other prevention measures that are a major concern for ICPs during renovations. (See related story, above.)
For example, an ICP whose hospital was undergoing a major construction project knew aspergillosis would be a threat, so she developed a comprehensive program that featured interactive training for both construction workers and health care staff. Renovation and remodeling involved two different buildings, which were connected on several different floors. "We have a bone marrow transplant unit and we do heart and kidney transplants," says Joan Wideman, MT(ASCP), MS, CIC, infection control specialist at Henry Ford Hospital in Detroit. "We were very much concerned about making sure that the environment for our patients and our employees was going to remain as safe as we could make it."
Wideman pulled together a collaborative team that included contractors, who constructed dust-tight temporary partitions and plastic barriers to ensure airborne fungi released during renovation would not find their way to vulnerable patients. An environment and air contamination checklist was developed so a "roving patrol" could routinely check that barriers were intact, traffic and air flow were appropriate, and construction debris was being safely removed. (See checklist, p. 9.) In addition, air sampling was done to check for increase in fungal spore counts, particularly near critical areas like surgical suites. "They knew if it went above a certain [threshold] to stop the project and check all of the seals," she says. A key to the success of the entire program was the education of construction workers and health care staff, she says.
"The bottom line with education was getting the workers involved," she says. "We took pictures of the workers in action at various levels, including some we [staged] to show things being done the wrong way." The technique reinforced the use of correct infection control measures, as workers identified unsealed barriers and other simulated breaches, she notes. "We had a two-pronged approach with the education," she says. "[First], we showed them what we expected of them, augmenting the policy with the photos. Then we had them view slide after slide and tell us what was right or wrong with the situation [depicted.] Having them analyze the situation is where we really made the change in their behavior. They had to dissect it and sometimes they would miss a few things. We would take that opportunity if no one had any further suggestions to point out [other breaches]."
Overall, nearly 300 construction workers and health care staff attended the training, and one result was that medical staff would be more likely to identify any hazards related to the construction. "That extended our ability to patrol by having the [health care workers] who were working at and near the sites as our eyes and ears," she says. Wideman estimates that the barriers, education, and other prevention efforts added about 10% to the cost of the project.
While such additional spending may seem expensive in an era of cost containment and cutbacks, it is well to remember that a single case of nosocomial aspergillosis can cost hundreds of thousands of dollars if a patient prevails in court, notes Andrew Streifel, MPH, REHS, hospital environment specialist at the University of Minnesota in Minneapolis. "We put on a construction management course every year, and one of the things we really try to stress is that this is becoming a standard of care," he says. "It will be judged. It’s much more definable, and I think there are some precedents now being set in the legal issues. There are regulators in the United States other than government, and that’s lawyers and insurance companies."
Streifel cites a case of a recently reported out-of-court settlement totaling $717,000 that began when a 55-year-old patient underwent surgery in a western Massachusetts hospital to repair herniated discs. During the surgical procedure, airborne A. fumigatus contaminated the surgical site, resulting in a disc space infection, according to a report on the settlement by the Massachusetts Lawyers Weekly.3 The patient had nine hospitalizations with two additional surgeries in the following year, spending a total of 115 days in the hospital. The patient eventually brought claims against a general contractor, an environmental testing company, and medical staff that included the chair of the infection control committee and the hospital ICP.
Records point finger at air ducts
"Hospital records suggested that water in the air handling ducts was a likely source of the fungus," the report stated. ". . . The plaintiff contended that the medical defendants were responsible for his infection because they failed to: find and eliminate the source of the fungus; appreciate the risk of cross-contamination; and do comprehensive testing in the individual operating rooms." After more than four years of litigation, the contractors settled for $117,000; the environmental testing company for $150,000; and the medical staff for a total of $450,000.
"The real bad news for them was that the person infected was a retired microbiologist," says Streifel, a frequent hospital consultant on environmental issues. "He knew this was odd." Similar cases likely go undetected, particularly those that result in death, because aspergillosis may not be suspected or detected postmortem, he adds. "We are not detecting these diseases as well as we should, simply because we are not autopsying the dead like we used to," he says. "That’s too expensive, if you will, and so the doctors’ doctors, the pathologists, are not seeing as much aspergillosis. Perhaps that’s due to the fact that they’re simply just not autopsying. We’re burying those mistakes."
References
1. Pegues DA, McNeil MM, Lasker BA, et al. Aspergillosis in a transplant ICU: Possible person-to-person airborne transmission. Abstract 19. Presented at the Infectious Disease Society of America Conference. Philadelphia; Nov. 18-21, 1999.
2. Carter CD, Barr BA. Infection control issues in construction and renovation. Infection Control Hosp Epidemiol 1997; 18:587-596.
3. Verdicts and settlements: Medical malpractice: Infection at Surgery Site — Fungus. Massachusetts Lawyers Weekly 1999; 27:2,674.
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