Efficacy of various disinfectants in killing a resistant strain of Pseudomonas aeruginosa by comparing zones of inhibition : Implications for endoscopic equipment reprocessing

• Published in: The American journal of gastroenterology Vol. 93; no. 11; pp. 2057 - 2059
• Main Authors: KOVACS, B. J, APRECIO, R. M, KETTERING, J. D, CHEN, Y. K
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing 01.11.1998
• Subjects: 2-Propanol - pharmacology; Agar; Biological and medical sciences; Cresols - pharmacology; Disinfectants - pharmacology; Drug Resistance, Microbial; Endoscopes; Endoscopes, Gastrointestinal; Endoscopy; Ethanol - pharmacology; Glutaral - pharmacology; Investigative techniques, diagnostic techniques (general aspects); Iodine - pharmacology; Medical sciences; Microbial Sensitivity Tests; Miscellaneous. Technology; Phenols - pharmacology; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Sodium Hypochlorite - pharmacology; Pseudomonadales; Human; Biomedical equipment; Digestive system; Disinfection; Glutaral; Gastrointestinal; Endoscope; Alcohol copolymer; Microorganism resistance; Repeated use; Efficiency; Bacteria; Pseudomonadaceae; Pseudomonas aeruginosa; Endoscopy; Disinfecting agent; Comparative study
• ISSN: 0002-9270; 1572-0241
• DOI: 10.1111/j.1572-0241.1998.00591.x

Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I.C. Spray and Virahol had the largest mean zones of inhibition (11.33 vs 20.60 and 20.55 mm; p = 0.0001). The hypochlorite compounds Chlorox (1:10 dilution) and Dispatch had mean zones of inhibition similar to that of Cidex (11.08 and 11.25 mm vs 11.33 mm; p = not significant). The phenolic compounds OMNI II and Lysol had mean zones of inhibition smaller than that of Cidex (10.50 and 10.35 mm vs 11.33 mm; p < 0.006), and the phosphoric acid and iodine-containing IodoFive had the smallest mean zone of inhibition (9.70 vs 11.33 mm; p = 0.0001). The alcohol-containing disinfectants had the largest zones of inhibition against resistant P. aeruginosa. These compounds may be more effective than glutaraldehyde for endoscopic equipment reprocessing.