Environmental samplings in the hospital: when, how and where?

Nolard, Nicole & Suzanne Heinemann

Author address: 

Mycology section - Scientific Institute of Public Health, Brussels, Belgium Email: [email protected]

Abstract: 

Background: Environmental samplings in hospitals should be adapted to different objectives. In care units where high risk patients are protected in laminar air flow rooms, environmental sampling is considered as quality control of the protective equipments and of precaution measures. In case of outbreak, sampling is often necessary to define the fungal source( s) and/or reservoirs, and to follow up the situation till complete remediation. Fungal analyses in hospital environments are also useful in order to check isolation measures in case of construction or renovation work or to control cleaning procedures. If in all cases, sampling methods are similar, the places to sample should be adapted and the results interpreted taking into account the context. Results: We have been monitoring Aspergillus in hospitals for 10 years and we will illustrate our experience with 3 situations. Surfaces were controlled with contact plates method, air was sampled with MAS device from Merck-Belgolabo (200 liters, 2 minutes); in both cases, we used medium Malt Extract Agar with Chloramphenicol. Lecture with identification to species level was performed after 2 and 3 days of incubation at 37°C. Situation 1: Routine surveys have been performed for 10 years in a haematological unit (sterile unit) composed of 6 laminar air flow rooms and 6 rooms without any air conditioning system. Two or three sets of samplings were realized each year in different patient's rooms and in all other types of areas of the unit. At the beginning of the survey, some results of surface analyses induced the revision of cleaning procedures and led to a higher motivation of the cleaning staff. Situation 2: Following an Aspergillus flavus sternitis outbreak after cardiac surgery, environmental samplings were performed in the whole operating suite and in other areas of the hospital. This survey allowed to point out a massive contamination of air and surfaces by A. flavus, and to localize the spore source in a non-medical area of the operating suite. The contamination level was followed-up during several months till normalisation. The clonal single-source of the contamination and the nosocomial origin of the aspergillosis cases were ascertained by molecular typing. Situation 3: Four clustered cases of aspergillosis due to A. fumigatus occurred within a week in the same unit of a small hospital specialized in long term treatment of chronic obstructive pulmonary patients. Environmental samplings performed didn't reveal high levels of contamination; based on our experience, it was our belief that this level of contamination could not explain the outbreak. Moreover there was no further case observed and it was assumed that the outbreak was due to a temporary contamination, perhaps linked to the huge amount of potted plants given to the nurses for New Year and placed for 2 or 3 weeks all along the unit corridor. Conclusion: Routine surveys should follow a well defined sampling plan, but, in case of outbreak it is essential to analyse precisely the situation, to imagine as much as possible the potential sources of fungal spores and to elaborate the sampling plan in order to check all these hypotheses. Therefore, it is sometimes necessary to sample non-medical areas or areas outside the concerned unit.
2000

abstract No: 

NULL

Full conference title: 

6th Congress of the European Confederation of Medical Mycology Societies
    • ECMM 6th (2000)