Sporicidal activity of disinfectants as one possible cause for bacteria in patient-ready endoscopes.

Four endoscopes were cleaned by an experienced endoscopy technician using an enzyme detergent solution with brushing, rinsing with tap water, and then high-level disinfection in an automatic endoscope reprocessing machine using CIDEX orthophthalaldehyde solution (CIDEX OPA). After disinfection, the channels of these patient-ready endoscopes were flushed with sterile neutralizing medium, brushed with a sterile brush, and then flushed again with sterile medium. The effluent from each flush was collected in sterile bottles, immediately returned on ice to a laboratory, and tested for the presence of bacteria. An average of about 200 colony-forming units of bacteria were recovered from each endoscope. Upon staining and microscopic examination, 3 of these colonies were spore-forming bacteria, and 7 colonies were nonspore-forming bacteria. These results suggest that the endoscopes might have been contaminated with a biofilm. Bacterial biofilms have been speculated to commonly occur in endoscopes as a result of the many possible inadequacies of cleaning, disinfecting, rinsing, drying, storage, and other functions associated with the difficulties of reprocessing endoscopes. As one possible cause for a biofilm, three high-level disinfectants (CIDEX activated dialdehyde solution, CIDEX OPA, and Aldahol high-level disinfectant) were tested for their sporicidal activity against high-protein or low-protein cultures of spore-forming bacteria in suspension. The potential importance of killing spore-forming bacteria within a practical exposure time in order to prevent the formation of biofilms is discussed.

Comparative sensitivity of 13 species of pathogenic bacteria to seven chemical germicides.

BACKGROUND: The relative resistance of diverse human bacterial pathogens to commonly used germicidal agents has not been established. METHODS: We measured by titration the survival of thirteen different bacteria after exposure to glutaraldehyde, formaldehyde, hydrogen peroxide, peracetic acid, cupric ascorbate, sodium hypochlorite, or phenol. RESULTS: Our comparative experiments allowed classification of the organisms' survival into four groups: (a) Pseudomonas aeruginosa and Staphylococcus aureus showed the most resistance, (b) Clostridium perfringens, Salmonella typhimurium, Staphylococcus epidermidis, and Escherichia coli O157:H7 showed intermediate resistance, (c) Listeria monocytogenes, Shigella sonnei, and Vibrio parahaemolyticus survived some treatments with chemical agents only in the presence of protecting protein (serum albumin), and (d) Vibrio cholerae, Vibrio vulnificus, Bacillus cereus, and Yersinia enterocolitica did not survive any of the treatments applied. CONCLUSION: We found species that more frequently survived exposure to germicidal agents were also those most commonly reported in association with hospital infections. Our findings suggest that resistance to disinfectants may be more important than pathogenicity in determining the relative prominence of an organism as an agent responsible for nosocomial infections.

Evaluation of the efficacy of a 3.2% glutaraldehyde product for disinfection of fibreoptic endoscopes with an automatic machine.

The efficacy of 'Cidex Plus' 3.2% alkaline glutaraldehyde was evaluated for the disinfection of fibreoptic endoscopes. The glutaraldehyde concentration in 'Cidex Plus', stored in an automatic machine (Olympus EW-20), remained higher than 2% (2.21%) even after a total of 102 disinfection cycles during 28 consecutive days. The results of the in-vitro study on antimicrobial activity showed that this alkaline glutaraldehyde product had a greater activity against 20 test organisms, including vegetative bacteria, bacterial spores, mycobacteria, and fungi, than 2% glutaraldehyde alone. The presence of 10 or 30% human serum did not appear to affect the activity of glutaraldehyde adversely. Instrument samples made from a variety of materials such as stainless steel, glass, teflon, etc. were not damaged after 168 h of immersion in alkaline glutaraldehyde, although it contained approximately 1.7 times more glutaraldehyde than 2% glutaraldehyde alone. Based on these results, 3.2% alkaline glutaraldehyde is considered to be a more effective disinfectant for fibreoptic endoscopes, with the use of an automatic machine, than 2% glutaraldehyde.