The number of immunocompromised patients in hospitals has increased, resulting in a concomitant increase in the number of Aspergillus spp infections, with an exceedingly high death rate. From January 1995 through June 1996, 7 patients acquired invasive aspergillosis at a Maryland hospital (Hospital A). No cases had been detected in 1994.
To determine risk factors for infection, we conducted a case-control study and an environmental evaluation. A case was defined as histopathologic evidence of invasive Aspergillus spp infection in any Hospital A patient admitted from January 1994 through July 1996.
Of 7 case patients identified, 5 were rheumatology patients hospitalized on 2 wards. Rheumatology case patients were more likely than randomly selected rheumatology patients without invasive Aspergillus spp infection (controls) to die (p = 0.004), to have longer hospitalization both in current (p = 0.008) and prior (p = 0.001) admissions, to receive high doses of intravenous immunosuppressive agents (p = 0.03), or to receive immunosuppressive agents for a longer period of time (p = 0.001). The environmental evaluation showed that construction areas were neither sealed off from patient care areas nor under negative pressure relative to patient-care areas. The air flow from patients' rooms was not positive in relation to the hallway and had only 1.6 air changes per hour.
This investigation suggests that rheumatology patients, particularly those receiving high dose intravenous immunosuppressive agents, are at increased risk of invasive Aspergillus spp infection. A high index of suspicion for the diagnosis of nosocomial aspergillosis should be maintained in these patients and, when hospitalized, they should be assigned to rooms removed from or physically separated from construction activity.