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

Bronchoscopy-related outbreaks and pseudo-outbreaks: A systematic review

OBJECTIVE

To identify and report the pathogens and sources of contamination associated with bronchoscopy-related outbreaks and pseudo-outbreaks.

DESIGN

Systematic review.

SETTING

Inpatient and outpatient outbreaks and pseudo-outbreaks after bronchoscopy.

METHODS

PubMed/Medline databases were searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, using the search terms "bronchoscopy," "outbreak," and "pseudo-outbreak" from inception until December 31, 2022. From eligible publications, data were extracted regarding the type of event, pathogen involved, and source of contamination. Pearson correlation was used to identify correlations between variables.

RESULTS

In total, 74 studies describing 23 outbreaks and 52 pseudo-outbreaks were included in this review. The major pathogens identified in these studies were Pseudomonas aeruginosa, Mycobacterium tuberculosis, nontuberculous mycobacteria (NTM), Klebsiella pneumoniae, Serratia marcescens, Stenotrophomonas maltophilia, Legionella pneumophila, and fungi. The primary sources of contamination were the use of contaminated water or contaminated topical anesthetics, dysfunction and contamination of bronchoscopes or automatic endoscope reprocessors, and inadequate disinfection of the bronchoscopes following procedures. Correlations were identified between primary bronchoscope defects and the identification of P. aeruginosa (r = 0.351; P = .002) and K. pneumoniae (r = 0.346; P = .002), and between the presence of a contaminated water source and NTM (r = 0.331; P = .004) or L. pneumophila (r = 0.280; P = .015).

CONCLUSIONS

Continued vigilance in bronchoscopy disinfection practices remains essential because outbreaks and pseudo-outbreaks continue to pose a significant risk to patient care, emphasizing the importance of stringent disinfection and quality control measures.

A systematic review and cost effectiveness analysis of reusable vs. single-use flexible bronchoscopes

The cost effectiveness of reusable vs. single‐use flexible bronchoscopy in the peri‐operative setting has yet to be determined. We therefore aimed to determine this and hypothesised that single‐use flexible bronchoscopes are cost effective compared with reusable flexible bronchoscopes. We conducted a systematic review of the literature, seeking all reports of cross‐contamination or infection following reusable bronchoscope use in any clinical setting. We calculated the incidence of these outcomes and then determined the cost per patient of treating clinical consequences of bronchoscope‐induced infection. We also performed a micro‐costing analysis to quantify the economics of reusable flexible bronchoscopes in the peri‐operative setting from a high‐throughput tertiary centre. This produced an accurate estimate of the cost per use of reusable flexible bronchoscopes. We then performed a cost effectiveness analysis, combining the data obtained from the systematic review and micro‐costing analysis. We included 16 studies, with a reported incidence of cross‐contamination or infection of 2.8%. In the micro‐costing analysis, the total cost per use of a reusable flexible bronchoscope was calculated to be £249 sterling. The cost per use of a single‐use flexible bronchoscope was £220 sterling. The cost effectiveness analysis demonstrated that reusable flexible bronchoscopes have a cost per patient use of £511 sterling due to the costs of treatment of infection. The findings from this study suggest benefits from the use of single‐use flexible bronchoscopes in terms of cost effectiveness, cross‐contamination and resource utilisation.

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.

Hospital water filters as a source of Mycobacterium avium complex

Bronchoscopes and the filters used for washing them were found to yield high numbers of Mycobacterium avium isolates sharing the same repetitive sequence-based PCR (rep-PCR) fingerprint pattern as M. avium isolates recovered from patient samples collected by bronchoscopy. Water and biofilm samples collected from the bronchoscopy preparation laboratory yielded M. avium, Mycobacterium intracellulare, Mycobacterium malmoense and Mycobacterium gordonae. Several M. avium and M. intracellulare isolates from water samples in the bronchoscopy laboratory had rep-PCR patterns matching those of patient bronchoscopy isolates. Five of the 22 (23 %) M. avium patient bronchoscopy isolates and 42 of the 56 (75 %) M. intracellulare patient bronchoscopy isolates could have been due to contamination from the water supply.

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.

Novel algorithm identifies species in a polymycobacterial sample by fluorescence capillary electrophoresis-based single-strand conformation polymorphism analysis

An algorithm to directly identify multiple mycobacterial species in a sample by using fluorescence capillary electrophoresis (FCE)-based single-strand conformation polymorphism (SSCP) analysis was developed. Part of the 16S-23S ribosomal DNA internal transcribed spacer (ITS) region in 37 reference strains and 73 clinical isolates representing 19 mycobacterial species and Mycobacterium tuberculosis complex was PCR amplified with a fluorescence-labeled mycobacterium-specific primer, 6-carboxyfluorescein-labeled primer Sp1f, and 5-hexachlorofluorescein-tagged Sp2r. FCE-SSCP analysis was applied to both undigested PCR products and the corresponding HaeIII-digested restriction fragments (RF) from each strain. The 23 resultant SSCP patterns distinguished all 19 species and M. tuberculosis complex. The technique is applicable for the detection of multiple mycobacterial species in a sample. It was demonstrated by analyzing two model mycobacterial communities consisting of five species with both rapidly and slowly growing species (model A) and four species commonly encountered in clinical practice (model B). The sensitivity study with spiked sputum samples with different amounts of M. tuberculosis H37Rv, M. avium, and M. intracellulare cells indicated that up to 25% of the amount of each mycobacterium could be detected relative to the two other species. Fifty-one sputum specimens analyzed by FCE-RF-SSCP were compared with the Amplicor assay (Roche Diagnostics GmbH). Species identified by both assays were always the same. Moreover, FCE-RF-SSCP could identify M. abscessus and M. kansasii, which are not targeted by Amplicor. FCE-RF-SSCP of sputum obtained from a patient with mixed M. avium and M. intracellulare infection gave SSCP patterns corresponding to these two species.

Nontuberculous mycobacteria in the environment

It is likely that the incidence of infection by environmental opportunistic mycobacteria will continue to rise. Part of the rise will be caused by the increased awareness of these microbes as human pathogens and improvements in methods of detection and culture. Clinicians and microbiologists will continue to be challenged by the introduction of new species to the already long list of mycobacterial opportunists (see Table 3). The incidence of infection will also rise because an increasing proportion of the population is aging or subject to some type of immunosuppression. A second reason for an increase in the incidence of environmental mycobacterial infection is that these microbes are everywhere. They are present in water, biofilms, soil, and aerosols. They are natural inhabitants of the human environment, especially drinking water distribution systems. Thus, it is likely that everyone is exposed on a daily basis. It is likely that certain human activities can lead to selection of mycobacteria. Important lessons have been taught by study of cases of hypersensitivity pneumonitis associated with exposure to metalworking fluid. First, the implicated metalworking fluids contained water, the likely source of the mycobacteria. Second, the metalworking fluids contain hydrocarbons (e.g., pine oils) and biocides (e.g., morpholine) both of which are substrates for the growth of mycobacteria [53,193]. Third, outbreak of disease followed disinfection of the metalworking fluid [136,137]. Although the metalworking fluid was contaminated with microorganisms, it was only after disinfection that symptoms developed in the workers. Because mycobacteria are resistant to disinfectants, it is likely that the recovery of the mycobacteria from the metalworking fluid [137] was caused by their selection. Disinfection may also contribute, in part, to the persistence of M avium and M intracellulare in drinking water distribution systems [33,89,240]. M avium and M intracellulare are many times more resistant to chlorine, chloramine, chlorine dioxide, and ozone than are other water-borne microorganisms [141,236]. Consequently, disinfection of drinking water results in selection of mycobacteria. In the absence of competitors, even the slowly growing mycobacteria can grow in the distribution system [33]. It is likely that hypersensitivity pneumonitis in lifeguards and therapy pool attendants [139] is caused by a similar scenario.

Efficacy of peroxygen compounds against glutaraldehyde-resistant mycobacteria

BACKGROUND

To prevent cross-infection of patients, semicritical devices must be high-level disinfected by a product capable of destroying mycobacteria. Glutaraldehyde is commonly used; however, recent studies showed that glutaraldehyde-resistant mycobacteria could survive treatment with this chemical for extended exposure times. Our study tested hydrogen peroxide, peracetic acid, and a germicide (Cidex PA, Advanced Sterilization Products, Irvine, Calif) containing a mixture of the 2 peroxygen compounds for their ability to kill both glutaraldehyde-resistant and nonresistant (control) mycobacteria.

METHODS

Bacterial suspensions were exposed to the test chemicals for various periods followed by neutralization and enumeration of survivors.

RESULTS

Hydrogen peroxide at 10% and acidified hydrogen peroxide at 6% had low activity (<4 log reduction in 60 minutes exposure) against glutaraldehyde-resistant strains and slightly higher activity (4 log to 6 log reduction in 60 minutes) against the control strains. Peracetic acid at 0.07% had low to moderate activity (0.6 log to 6 log reduction in 60 minutes) against the resistant organisms and moderate to high activity (4 log to 6 log reduction in 10 minutes) against the control strains. Cidex PA, which contains a mixture of 0.07% peracetic acid and 1% hydrogen peroxide, had high activity (6 log reduction in 10 minutes) against all organisms. Efficacy of 0.8% phenol, a standard reference solution, did not correlate with efficacy of the peroxygen compounds.

CONCLUSIONS

Hydrogen peroxide and peracetic acid had much higher activity toward mycobacteria when combined as a synergistic mixture than when evaluated individually.

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.