Objective: Adequate decontamination of surgical instruments plays a role in preventing transmission of infection. In 20041 we showed 100% of patient-ready endoscopes were contaminated with biofilm either in their air-water or working channels. Since then new methods of decontaminating endoscopes have been developed. In this study we have evaluated patient-ready endoscopes for residual bacterial contamination.
Methods: 40 air-water and 23 working channels, including 12 gastroscopes and 11 colonoscopes, were examined. Live bacteria were isolated by culture and identified by 16s rDNA sequencing. Quantitative real-time PCR of 16s rRNA gene was used to quantify the total number of bacteria present. Bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) were used for molecularly profiling of bacterial communities. Live/dead viability staining in conjunction with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to visually confirm bacterial viability and biofilm presence respectively.
Results: 40% of air-water channels and 50% of working channels were bacterial culture positive. PCR demonstrated an average of 2.8x103 and up to 3.1x105 bacteria/cm contaminating air-water channels whilst an average of 1.6x103 and up to 4.6x104 bacteria/cm contaminated working channels. The bacterial load of 17 (42.5%) air-water and 11 (47.8%) working channels was greater than 1x103 bacteria/cm and 14 of these were sent for pyrosequencing. A broad range of bacteria species were identified including Escherichia coli, Klebsiella, Shigella, Staphylococcus, Pseudomonas, Rastonia, Methylobacterium, Blastomonas, Fusobacterium, Bacillus and Sphingomonas spp. The bacteria in these samples were visually confirmed to be present as a biofilm by SEM. Bacteria within the biofilm were shown to be viable by live/dead staining and CLSM.
Conclusion: The percentage of patient-ready endoscopes contaminated with biofilm has decreased since the 2004 study suggesting better decontamination procedures. However, viable biofilm containing pathogenic species was confirmed contaminating approximately half of patient-ready endoscopes showing that more needs to be done.