Acid-fast bacillus contamination of a bronchoscope washing machine

Endoscope drying and its pitfalls

Inadequate drying of endoscope channels is a possible cause of replication and survival of remaining pathogens during storage. The presence during storage of potentially contaminated water in endoscope channels may promote bacterial proliferation and biofilm formation. An incomplete drying procedure or lack of drying and not storing in a vertical position are the most usual problems identified during drying and endoscope storage. Inadequate drying and storage procedures, together with inadequate cleaning and disinfection, are the most important sources of endoscope contamination and post-endoscopic infection. Flexible endoscopes may be dried in automated endoscope reprocessors (AERs), manually, or in drying/storage cabinets. Flushing of the endoscope channels with 70-90% ethyl or isopropyl alcohol followed by forced air drying is recommended by several guidelines. Current guidelines recommend that flexible endoscopes are stored in a vertical position in a closed, ventilated cupboard. Drying and storage cabinets have a drying system that circulates and forces the dry filtered air through the endoscope channels. Endoscope reprocessing guidelines are inconsistent with one another or give no exact recommendations about drying and storage of flexible endoscopes. There is no conclusive evidence on the length of time endoscopes can be safely stored before requiring re-disinfection and before they pose a contamination risk. To minimize the risk of disease transmission and nosocomial infection, modification and revision of guidelines are recommended as required to be consistent with one another.

Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy

Flexible endoscopy is a widely used diagnostic and therapeutic procedure. Contaminated endoscopes are the medical devices frequently associated with outbreaks of health care-associated infections. Accurate reprocessing of flexible endoscopes involves cleaning and high-level disinfection followed by rinsing and drying before storage. Most contemporary flexible endoscopes cannot be heat sterilized and are designed with multiple channels, which are difficult to clean and disinfect. The ability of bacteria to form biofilms on the inner channel surfaces can contribute to failure of the decontamination process. Implementation of microbiological surveillance of endoscope reprocessing is appropriate to detect early colonization and biofilm formation in the endoscope and to prevent contamination and infection in patients after endoscopic procedures. This review presents an overview of the infections and cross-contaminations related to flexible gastrointestinal endoscopy and bronchoscopy and illustrates the impact of biofilm on endoscope reprocessing and postendoscopic infection.

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.

Infection control in the bronchoscopy suite. A review

Bronchoscopy can occasionally transmit disease. Infection control in the bronchoscopy suite is especially important because of the risk of transmitting HIV or tuberculosis. Many case reports, patient series, and small studies have been published, but little comprehensive guidance is available for clinicians who wish to learn more about the problem and prevent it. We review the literature and describe three ways in which bronchoscopy can cause disease: by transmitting infections between patients, by transferring microorganisms within a patient, and by triggering coughing that can cause airborne infection of patients or health-care workers. Recommendations for infection control are listed; they include installing powerful air filters, using disposable bronchoscope suction valves, manually cleaning all equipment before disinfection, controlling patient coughing, and in some cases, giving patients prophylactic antibiotics.

Eradication of contaminating Mycobacterium chelonae from bronchofibrescopes and an automated bronchoscope disinfection machine

The results of a follow-up study concerning the decontamination of Mycobacterium chelonae subspecies abscessus from the bronchofibrescopes and the automated bronchoscope disinfection machine are described in this paper. After modification of the methods for disinfecting the bronchofibrescopes (adding a disinfection procedure with 70% alcohol before using the automated bronchoscope disinfection machine, increasing glutaraldehyde concentration to 3%, and changing the glutaraldehyde solution once a week), and the automated bronchoscope disinfection machine (recirculating used disinfectant), M. chelonae has not been detected from either the bronchofibrescopes or the automated bronchoscope disinfection machine (examined every 6 months for 4 yr by microscopy and cultures). Moreover, no M. chelonae has been clinically detected from bronchial washings for 4 yr.

Mycobacterial contamination of fibreoptic bronchoscopes

Because of the increasing numbers of immunosuppressed patients and the general resurgence of mycobacterial infection, diagnostic bronchoalveolar lavage (BAL) using a fibreoptic bronchoscope is an important and frequent procedure. A contaminated bronchoscope may introduce spurious mycobacteria into specimens causing diagnostic confusion, infect the patient with mycobacteria, or be a vehicle for cross-infection. Bronchoscopes are difficult to disinfect adequately if they are not properly cleaned (which may include stripping down channel valves) or are damaged. Bronchoscope washers have also contributed to the problem when glutaraldehyde becomes too dilute or they become heavily contaminated with environmental mycobacteria. Future solutions to prevent contamination include the regular maintenance of bronchoscopes and washers, having adequate cleaning and disinfection protocols and ensuring that they are adhered to, improving bronchoscope and washer design, and developing alternative disinfectants or new ways of using current ones. All these will probably have considerable cost implications for hospitals.

Audit of bronchoscope disinfection: a survey of procedures in England and Wales and incidents of mycobacterial contamination

Procedures used for cleaning/disinfection of fibreoptic bronchoscopes and incidents of mycobacterial contamination were assessed by postal questionnaire. Information supplied by the Infection Control Doctor in 129 of 198 hospitals (65.2%) was used to audit local practice for compliance with national guidelines. Discrepancies between recommended and local practice included lack of specification of detergent/cleaning agent (57%), inadequate contact time for chemical disinfection (40%) and the use of tap water rather than sterile water for rinsing the disinfected bronchoscope (39.7%). Other procedural anomalies associated with mycobacterial contamination included failure to adhere to manufacturers' instructions to dismantle valves prior to cleaning and to autoclave valves/accessories. The association of mycobacterial incidents with the use of automatic washer/disinfectors (17 of 18 incidents) together with Department of Health warnings of build-up of biofilm within these chemical-process machines gives further cause for concern.

Mycobacterial contamination of fibreoptic bronchoscopes

Contamination of bronchoalveolar lavage specimens by environmental mycobacteria in hospital water supplies may lead to diagnostic confusion, particularly in immunocompromised patients. Mycobacteria may become concentrated in the tubing of bronchoscope disinfecting machines. It is very difficult to eradicate these organisms once contamination has occurred.