Lessons from outbreaks associated with bronchoscopy.

Bronchoscopy is currently the most commonly employed invasive procedure in the practice of pulmonary medicine.1 An estimated 497,000 bronchoscopy procedures were performed in the United States in 1996.2 Current and new applications include bronchoscopic ultrasound, laser therapy, brachytherapy, electrocautery, cryotherapy, placement of airway stents, and balloon dilatation to relieve airway obstruction caused by airway lesions.3 Flexible endoscopes also are widely used in other medical disciplines. For example, more than 10,000,000 gastrointestinal endoscopies are performed each year.4 Endoscopes represent the medical devices most commonly linked to nosocomial outbreaks and pseudooutbreaks.5 Flexible endoscopes present a challenge for low-temperature sterilization or high-level disinfection, because they have long narrow lumens, cross-connections, mated surfaces, sharp angles, springs and valves, occluded dead ends, absorbent material, and rough or pitted surfaces.6,7 Failure to eradicate contamination that occurred during use may lead to person-to-person transmission of pathogens (eg, Mycobacterium tuberculosis); failure to prevent contamination during disinfection or storage may lead to outbreaks or pseudo-outbreaks from environmental microbes (eg, nontuberculous mycobacteria, or Rhodotorula rubra). In this issue, Sorin and colleagues8 describe the nosocomial transmission of an imipenemresistant strain of Pseudomonas aeruginosa, and Kressel and Kidd9 describe a pseudo-outbreak involving organisms relatively resistant to glutaraldehyde (ie, Mycobacterium chelonae and Methylobacterium mesophilicum) associated with the use of contaminated bronchoscopes. Prevention of endoscope-related infections requires strict adherence to current guidelines for cleaning and disinfection. Guidelines for disinfection of flexible endoscopes, including bronchoscopes, have been published by the Association for Professionals in Infection Control and Epidemiology, Inc.10,11 To date, nosocomial outbreaks have not been reported in which all current recommendations were followed scrupulously. These guidelines are based on sound scientific principles generated from several sources of data: first, studies on the natural bioburden of endoscopes and efficacy of cleaning; second, studies on the in vitro efficacy of recommended high-level disinfectants and low-temperature sterilization methods; third, studies of disinfection of simulated endoscopes or experimentally inoculated endoscopes; fourth, studies of the effectiveness of current high-level disinfection and sterilization methods in actual practice; and finally, lessons learned from outbreaks and pseudo-outbreaks involving endoscopes. Only limited data are available on the bioburden present on bronchoscopes following use. Alfa and Sitter reported the average load on bronchoscopes before cleaning was 6.4 104 colony-forming units (CFUs)/mL, with streptococci and normal upper respiratory flora being reported.12 The bioburden on used gastrointestinal endoscopes is higher, ranging from 106 to 107 CFUs for upper gastrointestinal endoscopes and 108 to 1010 CFUs for colonoscopes.13 Cleaning has been demonstrated to reduce the bioburden on endoscopes in most studies by more than 4 logs.13 Cleaning also removes organic and inorganic debris that may compromise the disinfection and sterilization process. For example, Alfa and colleagues tested several low-temperature sterilization methods (ie, ethylene