Investigation of a Pseudomonas aeruginosa Outbreak Related to Upper Endoscopy Procedures

BACKGROUND: In August 2003, a possible outbreak was reported to Infection Control by the endoscopy suite. Two patients had Pseudomonas aeruginosa isolates with identical sensitivity patterns. One case (P) had a chronic pancreatic pseudocyst that was drained by endoscopic ultrasound (EUS) on August 15, 2003. A bacterial culture done from the pseudocyst aspirate obtained during the procedure grew P. aeruginosa. A second case (M), had EUS done on August 21, 2003. On September 11, 2003, she had another EUS exam and fine needle aspiration (FNA) for further investigation of a mass with an additional bacterial culture that grew P. aeruginosa. METHOD: A formal outbreak investigation was initiated to determine the source of contamination and to limit the progress of the outbreak. Microbiologic sampling of implicated endoscope, the automated endoscope reprocessor, and tap water indicated the scope as the most likely source of contamination. All upper endoscopic cases done with the implicated scope during June–August 2003 were reviewed for P. aeruginosa. No other cases were identified. Survey of protocols identified compliance with AER manufacturer manual for use; current education on reprocessing; appropriate precleaning, cleaning, rinsing, and drying with documentation. All quality checks were done and documented appropriately. The implicated endoscope was sent to an independent device examination firm. The scope was found to have several defects. Ribotyping of six patient and linear scope P. aeruginosa isolates, plus two nosocomial isolates unrelated to the outbreak isolates, were submitted for genetic studies. RESULTS: Patients P and M were identified to have P. aeruginosa following EUS/FNA. The implicated endoscope was cultured and grew P. aeruginosa of identical genetic type to the ones recovered from both patients. This endoscope was also found to have several defects by an independent investigator and was taken out of service when clustering was initially detected. A replacement scope was obtained. CONCLUSIONS: Per agreement of GUH, CDC, and third-party endoscope expert, it was highly unlikely that washers could have caused this outbreak. The problem appeared limited to one endoscope during a brief period in August 2003. The implicated scope was in use since June 2001, and a recommendation was made to have scopes changed preventively every 12–18 months. Infection Control is initiating a competency program throughout the hospital that will provide education, training, and documentation for proper cleaning and high-level disinfection/sterilization of instruments.