Infection control failures lead to high body counts

High mortality outbreaks traced to lax measures

Infection control may not be a revenue-generating department, but the cost of forgetting its importance too often will be measured in lives rather than dollars. Case in point: Fifteen patients died last year in two outbreaks that were unrelated except for the poor infection-prevention efforts documented in each. Both outbreaks were reported recently in Atlanta at the annual meeting of the Epidemic Intelligence Service (EIS), the frontline medical detectives who investigate outbreaks at the Centers for Disease Control and Prevention (CDC).

In one case, the CDC recommended numerous infection-control measures after four patients died in an outbreak of invasive aspergillosis last year at a Los Angeles transplant center.1 However, the hospital did not adopt all of the recommendations, particularly one to treat high-risk patients with a chemoprophylaxis during an ongoing construction project at the facility. As a result, two more fatal infections occurred after the first outbreak. The hospital only had one case of aspergillosis in 1999 and two in 2000, so there may have been a perception — even in the wake of the initial outbreak — that all of the measures were unnecessary, reported Anil Panackal, MD, EIS officer at the CDC.

"The transplant surgeons at this hospital run the hospital essentially," he said. "They tended to be kind of stubborn about wanting to follow our recommendations. One reason possibly is that this hospital does a tremendous number of renal transplants a year — one of the highest in the country, if not the world. I think they became quite complacent about following recommendations from outsiders."

In the first phase of the investigation, the EIS officers conducted a retrospective cohort study among all renal transplant patients hospitalized from Jan. 1 to Feb. 5, 2001. Meanwhile, an environmental investigation was being done to assess ongoing construction activities and the adequacy of the hospital ventilation system. Clinical and environmental specimens were analyzed using DNA fingerprinting, and active surveillance for further cases was established.

Four cases of invasive aspergillosis were detected among 40 renal transplant patients identified during the period. "Unfortunately, all of them died within 11 days of diagnostic culture collection," Panackal said.

May have sprung from rain-soaked site

Factors associated with increased risk of invasive aspergillosis were: undergoing hemodialysis for more than four years prior to transplant; receiving corticosteroids more than 40 days; and receiving sirolimus, a new immunosuppressant. The use of sirolimus with mycophenolate (another immunosuppressant) was also associated with greater risk of infection.

"During January and February, heavy rainfall caused water damage to several areas of the hospital, including the renal transplant ward," he said. "Construction activity and remodeling were ongoing."

But the environmental barriers were limited to a fire door and a plastic sheet. In addition, the presence of health worker lockers in the area increased traffic to and from the work site and patient areas. The CDC recommended the creation of appropriate barriers between construction and patient care areas, and said immunosuppressed patients should wear protective respirators if they were being transported in the facility. Staff lockers should be relocated outside the construction site, and one service elevator should be used exclusively for the removal of construction debris. In addition, portable HEPA (high-efficiency particulate air) filters should be placed in the rooms of those at high risk. Finally, antifungal chemoprophylaxis was recommended for the high-risk patients.

"Unfortunately, these recommendations were not fully implemented by the transplant team," Panackal said. "Three additional renal transplant recipients developed invasive aspergillosis in the subsequent three months following our investigation. Two of those died."

Both outbreaks were likely a result of exposure to dust-borne Aspergillus, a well-known phenomenon during hospital construction.

"Similar DNA fingerprints between two clinical isolates suggested that the infecting organisms may have been acquired from a common source, most likely the hospital, although other environmental sources could not be excluded," he concluded. "Lack of adequate barriers between the construction site and immunosuppressed patients may have increased exposure to aspergillus species."

In another outbreak with even higher mortality, investigators concluded that plain old poor hand-washing compliance was a major contributor. Another fungal pathogen — Candida parapsilosis — caused nine fatal vascular catheter-associated bloodstream infections at a large Mississippi community hospital.2 To determine risk factors for infection and recommend control measures, the CDC conducted a case-control study and an environmental investigation.

Cases included all inpatients during the study period (April 1-Oct. 31, 2001) with a positive C. parapsilosis blood culture obtained at least 48 hours after admission. Two controls per case were matched by age group, primary service, and length of hospitalization prior to the case culture. Investi-gators identified a total of 22 cases, including 13 confirmed and seven possible.

"All had indwelling vascular catheters, and 41% [nine] died," said Thomas Clark, MD, a CDC EIS officer.

Factors associated with infection on univariate analysis included: severity of illness by APACHE II scores, mechanical ventilation, multiple catheters, dialysis catheters, and total parenteral nutrition (TPN). "Controlling for severity of illness, prolonged ventilation, [and] receiving TPN were independently associated with increased risk of C. parapsilosis BSI," he said.

Investigators cultured health care worker hands and observed their hand hygiene practices using a standardized data collection form. A hand hygiene opportunity was defined as the time from entrance into a patient room until departure, with washing indicated if the worker had direct contact with the patient.

"Before direct patient contact, nurses performed appropriate hand hygiene during 39% of observed opportunities and physicians during 18% of opportunities," Clark said.

Meanwhile, the fungal cultures were being obtained from the hands of workers, central-line housing, and insertion sites. C. parapsilosis grew from 18 of 69 pairs of worker hands. But its presence in the environment was limited to a blood pressure cuff; as catheter insertion sites, ports, and devices cultured were negative. Preliminary subtyping revealed some similar DNA fingerprints among patient blood and worker hands.

"No procedural irregularities were noted in TPN preparation and administration, central-line care, or in dialysis," Clark said.

It is possible TPN solutions became contaminated, but no evidence was found, he said. "I’m not sure where it came from [originally]. I was very concerned that we were missing an environmental reservoir. We did targeted culturing based on our epidemiology, looking very hard at anything that was common to nurses and multiple patients."

Epidemiologic, observational, and molecular data suggest colonized worker hands and poor hand hygiene compliance led to catheter colonization and subsequent blood infection in the severely ill patients.

"Our data support the hypothesis that C. parapsilosis was acquired exogenously from the hands of health care workers," Clark explained. "We found that one-quarter of health care workers carried the organism on their hands." A hand hygiene improvement plan was established that included promoting use of alcohol-based waterless rubs. In addition, a system for measuring and feeding back hand hygiene compliance results to workers caring for high-risk patients was set up.

References

1. Panackal AA, Dahlman A, Keil K, et al. Outbreak of invasive aspergillosis among renal transplant recipients — Los Angeles, 2001. Presented at the Epidemic Intelligence Conference. Atlanta; April 22-26, 2002.

2. Clark TA, Morgan J, Brandt M, et al. Hospital outbreak of Candida parapsilosis bloodstream infections — Mississippi, 2001. Presented at the Epidemic Intelligence Conference. Atlanta; April 22-26, 2002.