Whole-genome sequencing establishes persistence of biofilm-associated Pseudomonas aeruginosa detected from microbiological surveillance of gastrointestinal endoscopes

BACKGROUND

An increased incidence of Pseudomonas aeruginosa in microbiological surveillance (MS) cultures from gastrointestinal endoscopes was detected between March 2020 and March 2023 in Tan Tock Seng Hospital Singapore.

AIM

To describe the use of whole-genome sequencing (WGS) in this investigation.

METHODS

WGS was performed for all P. aeruginosa isolates with pairwise comparison of isolates to assess for genomic linkage. Comprehensive review of reprocessing practices and environmental sampling was performed.

FINDINGS

Twenty-two P. aeruginosa isolates were detected from endoscopic MS cultures. Fifteen (68%) isolates were available for WGS. Eighteen pairwise comparisons of isolates were made, of which 10 were found to be genomically linked. One endoscope had P. aeruginosa repeatedly cultured from subsequent MS that were genomically linked and persistent despite repeat endoscopic reprocessing, establishing the persistence of biofilm that could not be eradicated with routine reprocessing. All P. aeruginosa isolates cultured from other different endoscopes were genetically distinct. Investigation into reprocessing practices revealed the use of air/water valves connected to endoscopes during clinical use. Inspection of these valves revealed the presences of cracks and tears. All other environmental samples were negative.

CONCLUSION

The WGS findings helped to deprioritize common source contamination and supported the hypothesis of biofilm build-up within endoscopes, leading to repeatedly positive MS cultures that were genomically linked. This was possibly related to incomplete reprocessing of the damaged air/water valves, resulting in biofilm build-up. All faulty valves were changed and subsequently cleaned separately with ultrasonic cleaning followed by sterilization which resolved this incident.

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.

Systematic Review and Cost-Consequence Analysis of Ambu aScope 5 Broncho Compared with Reusable Flexible Bronchoscopes: Insights from Two US University Hospitals and an Academic Institution

OBJECTIVE

The aim of this study was to perform a systematic review, meta-analysis and cost-consequence analysis of the single-use bronchoscope, Ambu aScope^TM 5 Broncho, in relation to reusable flexible bronchoscopes (RFB) available within three high procedure volume university hospitals and academic institutions in the USA.

METHODS

The primary outcome was incremental cost and the secondary outcome was incremental cross-infection risk of use for both the single-use flexible bronchoscope (SUFB) and RFBs. Cost estimates included capital, repair, and reprocessing costs derived from a prospective observational micro-costing approach within three large university hospitals and academic institutions. All costs were valued in 2022 US dollars (USD). A meta-analysis based on literature covering cross-contamination and infection from 2010 to 2020 investigated cross-infection risk following bronchoscopy procedures with RFBs. Capital costs were discounted at 3% over 5-8 years. All parameters were evaluated using both univariate deterministic and probabilistic sensitivity analyses.

RESULTS

In high-volume hospitals, RFBs were cost minimizing compared to SUFBs. Probabilistic sensitivity analysis showed that RFBs were cost saving in 88% of iterations. Univariate analyses illustrated sensitivity of the base-case result to the procedure volume. Data from sensitivity analyses suggest that the two interventions are cost neutral at a break-even point of 756 procedures per year or 46 procedures per bronchoscope per year.

CONCLUSION

Assuming equivalent clinical performance, single-use flexible bronchoscopes are not cost minimizing when including the costs associated with cross-infection in high-volume US university hospitals and academic institutions. Overall, the benefits of conversion from RFBs to SUFBs are dependent on the annual procedure volume of individual hospitals, expected cross-infection risk, and purchase price of the aScope 5 Broncho.

Cross-contamination rate of reusable flexible bronchoscopes: A systematic literature review and meta-analysis

Background

Bronchoscopy is generally a safe and efficient procedure. However, the risk of cross-contamination with reusable flexible bronchoscopes (RFB) has been detected in several outbreaks worldwide.

Aim

To estimate the average cross-contamination rate of patient-ready RFBs based on available published data.

Methods

We performed a systematic literature review in PubMed and Embase to investigate the cross-contamination rate of RFB. Included studies identified indicator organisms or colony forming units (CFU) levels, and total number of samples >10. The Contamination threshold was defined according to the European Society of Gastrointestinal Endoscopy and European Society of Gastrointestinal Endoscopy Nurse and Associates (ESGE-ESGENA) guidelines. To calculate the total contamination rate, a random effects model was applied. Heterogeneity was analysed via a Q-test and illustrated in a forest plot. Publication bias was analysed via the Egger’s regression test and illustrated in a funnel plot.

Results

Eight studies fulfilled our inclusion criteria. The random effects model included 2169 samples and 149 events (positive tests). The total RFB cross-contamination rate was 8.69% ± 1.86 (standard division [SD]) (95% confidence interval [CI]: 5.06–12.33%). The result showed significant heterogeneity of 90% and publication bias.

Discussion

Significant heterogeneity and publication bias is likely associated with varying methodology and aversion towards publishing negative findings, respectively. Based on the cross-contamination rate an infection control paradigm shift is needed to ensure patient safety. We recommend to follow the Spaulding classification and classify RFBs as critical items. Accordingly, infection control measures such as obligatory surveillance, and implementing single-use alternatives must be considered where feasible.

Treating cancerous large airway stenosis with staging radioactive particle implantation guided by computed tomography and fiber bronchoscopy: a clinical study

Background

The purpose of this study is to investigate the clinical effectiveness of staging radioactive particle implantation guided by computed tomography (CT) and fiber–optic bronchoscopy in treating cancerous large airway stenosis.

Methods

A total of 102 patients were included; 57 had undergone staging radioactive particle implantation guided by CT and fiber bronchoscopy and 45 did not. Patients were evaluated by CT and fiber–optic bronchoscopy to determine the feasibility of the implantation of radioactive seeds for the treatment of cancerous large airway stenosis. The treatment planning system (TPS) was used to plan the doses. Radioactive seeds were implanted using fiber–optic bronchoscopy. One week later, CT-guided implantation of radioactive seeds was performed.

Results

The clinical evaluation showed complete, partial, slight, and non-response in 38, 14, 5, and 0 patients, respectively. None of the patients were found with serious complications. The diameter of the affected airway, Karnofsky score, dyspnea index, survival, and quality of life of the patients in both groups was significantly higher and significantly different after the treatment (P < 0.05). The dyspnea index was significantly lower in the treatment group as compared with the control group (P < 0.001).

Conclusion

CT- and fiber bronchoscopy-guided staging radioactive particle implantation has definite treatment effectiveness in treating cancerous large airway stenosis. It should be widely used in clinical practices.

Outbreak of pulmonary Pseudomonas aeruginosa and Stenotrophomonas maltophilia infections related to contaminated bronchoscope suction valves, Lyon, France, 2014

In April 2014, pulmonary Pseudomonas aeruginosa and Stenotrophomonas maltophilia co-infections potentially related to bronchoscopic procedures were identified in the intensive care units of a university hospital in Lyon, France. A retrospective cohort of 157 patients exposed to bronchoscopes from 1 December 2013 to 17 June 2014 was analysed. Environmental samples of suspected endoscopes were cultured. Bronchoscope disinfection was reviewed. Ten cases of pulmonary P. aeruginosa/S. maltophilia co-infections were identified, including two patients with secondary pneumonia. Eight cases were linked to bronchoscope A1 and two to bronchoscope A2. Cultures deriving from suction valves were positive for P. aeruginosa/S. maltophilia. Exposure to bronchoscopes A1 and A2 was independently coupled with increased risk of co-infection (adjusted odds ratio (aOR) = 84.6; 95% confidence interval (CI): 9.3-771.6 and aOR = 11.8, 95% CI: 1.2-121.3). Isolates from suction valves and clinical samples presented identical pulsotypes. The audit detected deficiencies in endoscope disinfection. No further cases occurred after discontinuation of the implicated bronchoscopes and change in cleaning procedures. This outbreak of pulmonary P. aeruginosa/S. maltophilia co-infections was caused by suction valve contamination of two bronchoscopes of the same manufacturer. Our findings underscore the need to test suction valves, in addition to bronchoscope channels, for routine detection of bacteria.

Investigation of a Candida guilliermondii Pseudo-outbreak Reveals a Novel Source of Laboratory Contamination

Candida guilliermondii was isolated from sterile specimens with increasing frequency over a several-month period despite a paucity of clinical evidence suggesting true Candida infections. However, a health care-associated outbreak was strongly considered due to growth patterns in the microbiology laboratory that were more consistent with true infection than environmental contamination. Therefore, an extensive investigation was performed to identify its cause. With the exception of one case, patient clinical courses were not consistent with true invasive fungal infections. Furthermore, no epidemiologic link between patients was identified. Rather, extensive environmental sampling revealed C. guilliermondii in an anaerobic holding jar in the clinical microbiology laboratory, where anaerobic plates were prereduced and held before inoculating specimens. C. guilliermondii grows poorly under anaerobic conditions. Thus, we postulate that anaerobic plates became intermittently contaminated. Passaging from intermittently contaminated anaerobic plates to primary quadrants of aerobic media during specimen planting yielded a colonial growth pattern typical for true specimen infection, thus obscuring laboratory contamination. A molecular evaluation of the C. guilliermondii isolates confirmed a common source for pseudo-outbreak cases but not for the one true infection. In line with Reason's model of organizational accidents, active and latent errors coincided to contribute to the pseudo-outbreak. These included organism factors (lack of growth in anaerobic conditions obscuring plate contamination), human factors (lack of strict adherence to plating order, leading to only intermittent observation of aerobic plate positivity), and laboratory factors (novel equipment). All of these variables should be considered when evaluating possible laboratory-based pseudo-outbreaks.

Infectious diseases linked to cross-contamination of flexible endoscopes

Flexible endoscopes are widely used to examine, diagnose, and treat medical disorders. While the risk of endoscopy-related transmission of infection is estimated to be very low, more health care-associated infections are related to contaminated endoscopes than to any other medical device. Flexible endoscopes can get highly contaminated with microorganisms, secretions and blood during use. The narrow lumens and multiple internal channels make the cleaning of flexible endoscopes a complex and difficult task. Despite the availability of international, national and local endoscope reprocessing guidelines, contamination and transmission of microorganisms continue to occur. These transmissions are mostly related to the use of defective equipment, endoscope reprocessing failures, and noncompliance with recommended guidelines. This article presents an overview of publications about case reports and outbreaks related to contamination of flexible endoscopes.