Invasive Aspergillosis in a paediatric oncology unit possible environmental factors

E. Price1, A. Shankar1, D. Samuel1, M. Millar1, V. Saha1 & P. Hoffman2

Author address: 

1Depts of Microbiology & Paediatric Oncology, Royal London Hospital, E12ES; 2Health Protection Agency, Colindale, London NW9 5HT


Background In spite of many initiatives, there were 5 proven and 6 probable invasive aspergillosis cases in a paediatric oncology unit over 2 years, starting June 2001. Significant aspergillus exposure outside hospital was possible for at least 3 patients, possibly more. However, in the preceding 2 years there had only been one case. In the second time period, the unit had been closed twice for review, investigation and cleaning. Hypochlorite disinfection for recycling air-coolers, fans and taps had been introduced. Although these patients were moved around the unit, the majority were nursed predominantly in the non-HEPA filtered area & all had some exposure to it. This study reviews microbiological results & compares environmental changes with case detection dates. Results Environment Onset of case detection coincided with window closure, intended to provide protection from local building work. Direct cultures from possible sources, including air-coolers, did not show significant positive results. Water supply cultures were positive from 4 of 16 filtered samples (50mls). Aspergillus air counts were lower than in adjacent wards. Patients 6 patients were culture positive from respiratory samples (including one first admission sample) and 1 patient from an invasive skin lesion. Diagnosis in the remaining patients was made radiologically. Although more intensive chemotherapy was used in the second time period, this could have contributed to infection in no more than 3 of the patients. Conclusion Window closure was circumstantially related to case detection. It may have increased humidity, possibly influencing spore germination. A recent requirement to reduce window opening to 10 cm in all patient areas could have contributed. Intermittent release of spores and frequent cleaning, may account for lack of significant environment cultures. Possible sources include the humid bathroom area, air-coolers and external building work. As originally intended for this unit, presentday oncology units need to be fully HEPA filtered. The factors that predispose to colonization of patients in non-HEPA filtered hospital areas or in the home, remain problematic.

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Full conference title: 

Federation of Infection Societies conference
    • FIS (2007)