Persistent residual contamination in endoscope channels; a fluorescence epimicroscopy study.

BACKGROUND AND STUDY AIMS: The increasing demand for endoscopic procedures poses new contamination challenges, given developing antimicrobial resistance worldwide and potential viral or prion diseases in populations at risk. We examined working channels from reusable luminal endoscopes used in recent years. METHODS: Very sensitive fluorescence epimicroscopy was used to examine working channels from 6 decommissioned and 6 factory-new channels, as received, or following spiking and washing in the laboratory. RESULTS: After a single contamination and wash test cycle, new channels retained approximately 75 pg/mm(2) of proteins; through 7 subsequent cycles residual proteins fluctuated between 25 and 75 pg/mm(2). Decommissioned channels harbored 1 - 4 µg of proteins each, except in one gastroscope (33 µg), including up to 2 % amyloid proteins except in one gastroscope and one sigmoidoscope (with over 80 %); lumens showed wearing with established abraded biofilms in 3 cases. After spiking with scrapie-infected blood components and washing, residual protein levels in new channels varied following standard (17.23 pg/mm(2)), duplicated (2.39 pg/mm(2)) or extended (11.3 pg/mm(2)) washing; no changes were measured among the long-established contamination in old channels. CONCLUSIONS: Our observations suggest that wear effects in endoscope lumens may contribute to the adsorption of proteins, thus facilitating retention and survival of bacteria. As demonstrated by recent outbreaks worldwide despite recommended reprocessing, the development of antimicrobial-resistant bacterial strains, and the estimated prevalence of variant Creutzfeldt-Jakob disease (vCJD) in the UK particularly, combined with increasing demand for endoscopic procedures, call for sustained precautions and improved methods for the reprocessing of nonautoclavable, reusable surgical instruments.

Rigid sigmoidoscopy: a potential hazard for cross-contamination.

BACKGROUND: Rigid sigmoidoscopy using a disposable or nondisposable sigmoidoscope is a common outpatient procedure. It has been assumed that the nondisposable bellows and light head of the sigmoidoscope remain free from enteric organisms so that the procedure is sterile if a disposable or nondisposable (metal) sigmoidoscope shaft is used. The aim of this study was to identify the presence of organisms within the bellows or light head of the sigmoidoscope. METHODS: Of 21 patients undergoing rigid sigmoidoscopy with a disposable instrument, bacterial cultures were taken from the inside of sterile Jackson-Pratt bulbs in 12 patients, with the bulbs being used to simulate the nondisposable insufflation bellows. In an additional nine patients, swabs were taken for culture from the inside of the nondisposable light head. RESULTS: Enteric gram-negative Escherichia coli and mixed anaerobic organisms were cultured from the Jackson-Pratt bulbs in two cases, and gram-positive organisms were cultured in another case. Gram-negative organisms, including Bacillus, Proteus mirabilis, Klebsiella, and Enterococcus faecalis, were cultured from the inside of the light head in two cases. CONCLUSION: Sigmoidoscopy using a disposable instrument is not a sterile procedure and may pose a risk of patient-to-patient cross-contamination by potentially harboring organisms in the bellows or light head.

Quality control in colorectal cancer screening: systematic microbiological investigation of endoscopes used in the NORCCAP (Norwegian Colorectal Cancer Prevention) trial.

BACKGROUND: Endoscopic colorectal cancer (CRC) screening is currently implemented in many countries. Since endoscopes cannot be sterilised, the transmission of infectious agents through endoscopes has been a matter of concern. We report on a continuous quality control programme in a large-scale randomised controlled trial on flexible sigmoidoscopy screening of an average-risk population. Continuously, throughout a two-year screening period, series of microbiological samples were taken from cleaned ready-to-use endoscopes and cultured for bacterial growth. RESULTS: 8573 endoscopies were performed during the trial period. Altogether, 178 microbiological samples (2%) were taken from the biopsy channels and surfaces from the endoscopes. One sample (0.5%) showed faecal contamination (Enterobacter cloacae), and 25 samples (14%) showed growth of environmental bacteria. CONCLUSIONS: Growth of bacteria occurs in a clinical significant number of samples from ready-to-use endoscopes. Pathogenic bacteria, however, were found only in one sample. Improvement of equipment design and cleaning procedures are desirable and continuous microbiological surveillance of endoscopes used in CRC screening is recommended.