The Identification of Stenotrophomonas maltophilia Contamination in Ultrasound Endoscopes and Reproduction of Decontamination Failure by Deliberate Soiling Tests

Abstract

Background: An outbreak of Stenotrophomonas maltophilia was observed in the cultures of bronchial aspirations. After systematic culturing of the scopes and reprocessing the equipment, it turned out to be a pseudo-outbreak caused by a failure of the disinfector to sterilize ultrasound scopes, subsequently resulting in cross infection of the bronchoscopes via the connecting tubes in the dryer. Objectives: To support the above-mentioned findings and to show how different variables influence the decontamination process. Methods: The ultrasound scopes were deliberately contaminated with test soil and subsequently disinfected with peracetic acid (PAA), glutaraldehyde (GA) and hot water. Cultures were taken immediately after disinfection and after 4 days in the drying cabinet. Results: After disinfection with PAA, persistent contamination was observed in the endobronchial ultrasound scope, and after disinfection with PAA and prolonged storage in the drying cabinet, contamination of the endoscopic ultrasound scope persisted. All ultrasound scopes were effectively disinfected with GA. Conclusion: It is concluded that disinfection with PAA fails to decontaminate the small channels of the ultrasound scopes. Prolonged storage in humid conditions seems to enhance the outgrowth of microorganisms. By reassignment of all endoscopes to fixed locations in the drying cabinet, by using disposable connector tubes for the balloon channels, and by using GA instead of PAA, the reprocessing procedure in our hospital was corrected effectively.