Identification of Nosocomial Aspergillus fumigatus Using Virtual Surveillance

BACKGROUND: In February 2003, data-mining (DM) surveillance revealed a 190% (p=0.004) increase from baseline of A. fumigatus respiratory isolates for a total of eight. Upon review of locations, it was found that four of eight isolates had been cultured from two units served by the same air handler. METHODS: Line listings provided by DM confirmed that isolates were hospital-acquired. Lab was consulted to rule out possible contamination of specimens in the laboratory. Since HVAC systems are often suspect in cases of hospital-acquired Aspergillus, the air handlers were examined. Fungal cultures were obtained from the final filters of the suspect HVAC. Cultures grew out A. fumigatus. Physical inspection of the filters revealed that they had not been seated properly, allowing some passage of unfiltered air. The filters were replaced and seated properly. Cultures were repeated and were negative for A. fumigatus. In addition to replacing the filters, engineering staff was reeducated on installation of final filters. RESULTS: Surveillance for hospital-acquired A. fumigatus has been continued. DM confirmed an 80% decrease (p =0.034). CONCLUSION: Proper installation of HVAC final filters is essential for prevention of hospital-acquired Aspergillus. DM is beneficial in early identification of potentially serious clusters of isolates and provides enhanced surveillance, which will help organizations meet 2005 JCAHO standards.