Evidence-based spectrum of antimicrobial activity for disinfection of bronchoscopes

SUMMARY: Processing of bronchoscopes after a physical examination has to eliminate all micro-organisms that could have contaminated the endoscope and that may harm the following patient. The aim of this analysis is to define those micro-organisms that may contaminate the bronchoscope during the examination and that may cause disease in other patients. METHODS: Research of literature and analysis of laboratory data. RESULTS: During the passage of the respiratory tract the bronchoscope will be contaminated by the physiological flora of oral cavity, nasopharynx, trachea, bronchi, and pulmonary tissues. Whilst the oral cavity, the nasopharynx and the pharynx are the habitat for a great variety of bacteria the lower respiratory tract is virtually free of micro-organisms. However, in ventilated patients trachea and bronchi can become colonized as the result of bypassing the cleansing effect of the ciliated epithelium. In addition all agents that can cause bronchitis or pneumonia in immunocompromised or otherwise healthy individuals are potential contaminants of bronchoscopes. These microorganisms include bacteria, mycobacteria, yeasts and moulds, enveloped and non-enveloped viruses and rarely parasites. The bronchoscopic procedure can result in epithelial injury with subsequent bleeding. Therefore, all blood-borne pathogens, e.g. HIV or HBV are also potential contaminants of the bronchoscope. There are several reports of transmission of micro-organisms due to incomplete or faulty cleaning and disinfection procedures of bronchoscopes. These incidents include nearly all classes of micro-organisms but not parasites or viruses. However, the incubation period of viruses can be long and the association between bronchoscopy and infection may be obscure. Endospore forming micro-organisms and parasites are not part of the normal flora of the respiratory tract and may rarely cause disease, usually only in severely immunocompromised patients, but transmission of such organisms by bronchoscopy has never been reported. CONCLUSION: The antimicrobial activity of the disinfection process, including chemical disinfectants for endoscopes has to include bacteria, fungi and viruses. Sporicidal activity may be only warranted in specific patient populations, i.e. after bronchoscopy of suspected anthrax patients or before examination of severely immunocompromised patients.