Rinsability of orthophthalaldehyde from endoscopes.

Orthophthalaldehyde high level disinfectants are contraindicated for use with urological instruments such as cystoscopes due to anaphylaxis-like allergic reactions during surveillance of bladder cancer patients. Allergic reactions and mucosal injuries have also been reported following colonoscopy, laryngoscopy, and transesophageal echocardiography with devices disinfected using orthophthalaldehyde. Possibly these endoscopes were not adequately rinsed after disinfection by orthophthalaldehyde. We examined this possibility by means of a zone-of-inhibition test, and also a test to extract residues of orthophthalaldehyde with acetonitrile, from sections of endoscope insertion tube materials, to measure the presence of alkaline glutaraldehyde, or glutaraldehyde plus 20% w/w isopropanol, or ortho-phthalaldehyde that remained on the endoscope materials after exposure to these disinfectants followed by a series of rinses in water, or by aeration overnight. Zones of any size indicated the disinfectant had not been rinsed away from the endoscope material. There were no zones of inhibition surrounding endoscope materials soaked in glutaraldehyde or glutaraldehyde plus isopropanol after three serial water rinses according to manufacturers' rinsing directions. The endoscope material soaked in orthophthalaldehyde produced zones of inhibition even after fifteen serial rinses with water. Orthophthalaldehyde was extracted from the rinsed endoscope material by acetonitrile. These data, and other information, indicate that the high level disinfectant orthophthalaldehyde, also known as 1,2-benzene dialdehyde, cannot be rinsed away from flexible endoscope material with any practical number of rinses with water, or by drying overnight.

Aldahol high-level disinfectant.

BACKGROUND: Glutaraldehyde and ortho-phthalaldehyde (OPA) are widely used as the active ingredients of high level disinfectants for heat-sensitive, semicritical medical instruments. However, both of these chemicals have limitations in their spectrum of antimicrobial activity. Glutaraldehyde disinfectants are poorly mycobactericidal, and require impractically long exposure times to kill spore-forming bacteria. OPA disinfectants kill many types of mycobacteria in practical exposure times, but require 32 hours to pass the Association of Official Analytical Chemists (AOAC) sporicidal test, and do not claim to be sterilants. These could be serious limitations that contribute to the formation of biofilms in endoscopes, after which the endoscopes are difficult to disinfect. The objective of our research was to discover a disinfectant formulation, based on aldehydes, that killed mycobacteria and spore-forming bacteria in a practical exposure time and temperature. METHODS: Solutions of glutaraldehyde or OPA were prepared with various concentrations of alcohols, sodium and potassium salts, chelating agents, and detergents at alkaline pH values, and tested against cultures of mycobacteria and spore-forming bacteria to find a formulation that would kill these bacteria in practical exposure times at 20 degrees C or 25 degrees C. RESULTS: Concentrations of < or =20% w/w isopropanol and < or =8% potassium acetate in combination with < or =3.5% w/w glutaraldehyde at alkaline pH values killed 6 log(10) of mycobacteria within 10 minutes at 20 degrees C. Similar combinations killed 6 log(10) of Bacillus subtilis in suspension within 30 minutes at 25 degrees C, and B subtilis within 60 minutes at 20 degrees C. The sporicidal activity of OPA was not increased by combination with isopropanol and potassium acetate salts. CONCLUSIONS: Aldahol high-level disinfectant (US FDA K041360), a formulation of 3.5% glutaraldehyde in combination with 20% w/w isopropanol and 8% potassium acetate, kills mycobacteria within 10 minutes at 20 degrees C and kills 6 log(10) of cultures of the spore-forming bacteria B subtilis within 60 minutes at 20 degrees C.

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.

Studies of polyester fiber as carrier for microbes in a quantitative test method for disinfectants.

Tests were conducted by a Task Force on Disinfectant Test Methods that was appointed to investigate controversies regarding the accuracy of AOAC test methods for disinfectants as presented in AOAC's Official Methods of Analysis, Chapter 6. The general principles for new and improved AOAC tests are discussed, and a disinfectant test using microbes labeled onto a polyester fiber surface is described. The quantitative test measures the survival of test microbes as a function of exposure time as well as the exposure conditions required to kill 6 log10 of the test microbes. The time required was similar to that for the kinetics of the kill of Bacillus subtilis-labeled cylinders as tested by methods of the AOAC Sporicidal Test 966.04.