Aseptic preparation under compounding isolator: when detergent contaminates us.
15 October 2026
C. Mennecart 1, F. Kerouredan 1, M. Sangnier 2, C. Bataille 3, S. Bouchard-Cresto 4, C. Bervas 3, A. Berroneau 1, G. Bouguéon 1,51. Pharmaceutical Technology Department, Bordeaux University Hospital, Pessac, France
2. Pharmaceutical Technology Department, Hospital Group of Saintes-Saint-Jean-d’Angely, Saintes, France
3. Infection Prevention and Control Unit, Bordeaux University Hospital, Bordeaux, France
4. Environmental microbiology laboratory, Bordeaux University Hospital, Bordeaux, France
5. ARNA laboratory, ChemBioPharm, INSERM U1212, UMR 5320 CNRS, University of Bordeaux
Context and objectives
During renovation work carried out at our sterile drug preparation unit (SDPU), five consecutive daily instances of contamination by the bacterium Ralstonia insidiosa were detected in an aseptic compounding isolator (ACI). The aim of this study is to reconstruct the sequence of events retrospectively, to assess the appropriateness of the measures taken at the time and to highlight their limitations.
Materials and Methods
Our SDPU is equipped with four ACIs. The microbiological monitoring plan in place follows the recommendations of the 2023 Good Preparation Practices (GPP) (2 glove swabs and 2 sedimentation tests per ACI per day). A cleaning protocol combining the use of a detergent and a disinfectant (both in 1L spray bottles), applied twice daily, is used. A multidisciplinary team comprising the pharmacy and the environmental microbiology laboratory has reconstructed the sequence of events.
Results-Discussion
Ralstonia insidiosa was detected in 5 samples (1 sample per day) out of the 20 samples taken and scheduled in an ACI (2 glove swabs, 3 sedimentation agar plates). The investigation into the source of this waterborne bacterium, which was traced back to several possible sources (staff airlock, refrigerators, cleaning products) concluded after 15 days of investigation that a batch of detergent had been contaminated (positive samples found on both opened and unopened bottles).
The review of this event reveals the teams’ appropriate response. Immediate measures were taken before the strain responsible was identified: the contaminated ACI was taken out of use, general decontamination was carried out, cleaning procedures were stepped up, and monitoring of environmental samples was intensified. As soon as the detergent was suspected as the source of contamination, it was replaced with another batch free from contamination (internal checks carried out). Certain limitations should be highlighted: the delay in identifying the detergent as a potential source of contamination, and the lack of a contingency cleaning protocol in the event that the product is unavailable.
The investigations carried out by the manufacturer during this event revealed contamination in a single batch, which was withdrawn from the market seven weeks after the events began. This detergent is now sold in a radiosterilised form.
Conclusion
This incident confirms the need to put in place appropriate action plans in the event of microbiological contamination of ACIs. It also highlights the importance of not underestimating potential sources of contamination and of carrying out thorough and comprehensive investigations.
Key words: controlled environment, microbiology, disinfection