Aspergillus outbreak in an oncology unit: Control measures. Case-control study, and molecular typing

C. L. Thio, D. Smith, G. Bova, C. Cooper, L. Gay, R. Gilpin, William G Merz, C. Miller, Trish M Perl

Research output: Contribution to journalArticlepeer-review


Aspergillus, a ubiquitous fungus, is the leading cause of nosocomial pneumonia in bone marrow transplant (BMT) and leukemic patients undergoing chemotherapy. Our routine surveillance uses standard criteria to define invasive fungal infections (IFI) in BMT and leukemic patients. In 1996, we detected 29 IFI cases, up from 9 in 1995, which were primarily clustered from January to March and September to November. Initial control measures included obtaining monthly air samples, reviewing the ventilation system and physical plant, changing the traffic pattern into the unit, and having patients wear N95 masks outside their rooms. Two of 9 room cultures and no air samples grew Aspergillus flavus (AF). Random amplified polymorphic DNA analysis revealed that one environmental and three patient isolates were identical suggesting a point source. Despite the control measures in place, additional cases developed. We matched 21 culture confirmed or probable (symptoms plus radiologie evidence) invasive AF cases to 20 control subjects without AF to determine risk factors for developing AF. Cases carried the diagnosis of cancer for a longer time (p=0.007, median 69 vs. 509 days) and were clustered on one side of the floor near a stairwell (p=0.054). The length of neutropenia, days of antibiotic therapy or parenteral nutrition, number of radiology visits, and chemotherapy protocol did not differ between the groups (p=NS). In the fall, additional cultures were obtained and 3 of 9 patient room cultures grew AF. Rooms, at patient discharge, were found to be inadequately cleaned, hence housekeeping standards were reinforced and the stairwell near the cluster of cases was closed. These control measures successfully stopped the outbreak. Molecular typing of these patient and room isolates is pending. A multidisciplinary effort is necessary to control aspergillus infections. Molecular typing may be a useful adjunct to determine a point source and to direct control measures.

Original languageEnglish (US)
Pages (from-to)417
Number of pages1
JournalClinical Infectious Diseases
Issue number2
StatePublished - 1997

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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