Heavy contamination of operating room air by Penicillium species: identification of the source and attempts at decontamination.

Increased rates of nosocomial infection caused by filamentous fungi in immunocompromised patients prompted microbiologic surveillance of the central air handling systems in our hospital. During a 4-year period, Penicillium species were isolated from 47 patients, including two with surgical wound infections caused by Penicillium. Counts of Penicillium in operating room air were much higher (195 colony-forming units [CFU]/m3) than in 95% filtered corridor air (14.6 CFU/m3; p less than 0.01). Ventilation ducts and terminal units lined with fiberglass in the operating room air handling system were heavily contaminated by Penicillium; the fiberglass was also contaminated with Aspergillus species. Corrective measures included filter replacement and decontamination of the ventilation system with aerosolized chlorine solution. Although operating room air remained free of filamentous fungi during the next 7 months, contamination eventually recurred and required repeated decontamination. We believe that certification guidelines are highly desirable for hospital ventilation systems, especially if the system serves immunocompromised patients.