Susceptibility of Pseudomonas aeruginosa and Acinetobacter baumannii biofilms grown on denture acrylic to denture-cleaning agents and sonication

BackgroundDentures can act as reservoirs for microorganisms that cause local and systemic diseases, including opportunistic pathogens Pseudomonas aeruginosa and Acinetobacter spp, leading causes of hospital-acquired pneumonia. ObjectivesTo determine the efficacy of a brief cleaning protocol with four commonly used denture cleaning agents combined with ultra-sonic cleaning on P. aeruginosa and A. baumannii biofilms grown on denture acrylic. The effectiveness of a commercial sonicator on bacterial biofilm reduction was also evaluated. Materials and MethodsP. aeruginosa and A. baumannii 48 h biofilms were grown in artificial saliva on polymethyl methacrylate (PMMA) discs, exposed to four disinfectants, with or without ultra-sonication, for 1 min and the number of viable bacteria post-exposure to the treatment determined. P. aeruginosa biofilms were exposed for one or five mins to two disinfectants plus a commercial sonicator. ResultsUltra-sonication alone reduced total viable biofilm from 67.3% (A. baumannii) to 94.8% (P. aeruginosa). Without ultra-sonication, 0.012% sodium hypochlorite, Steradent(R) Active Plus and Ecolab(R) 0.2% chlorhexidine reduced P. aeruginosa and A. baumannii biofilms viable counts by between 99.3% and >99.99%. Sonication further reduced 99.3% kill to undetectable levels (>99.99% kill). Colgate(R)Total Pro-Gum Health Daily mouthwash reduced P. aeruginosa by 17% and A. baumannii biofilms by 2.1 log. These number were further reduced by >99.99% with sonication (p=<0.001). Domestic sonicators, such as those for cleaning jewellery at home, were effective when used in conjunction with denture cleaning agents. ConclusionRapid reduction of P. aeruginosa and A. baumannii biofilms on denture acrylic is possible with denture-cleaning agents and sonication HighlightsO_LIFour antimicrobial agents tested against P. aeruginosa and A. baumannii biofilms C_LIO_LI0.012% NaOCl and Steradent Active Plus were the most effective agents tested C_LIO_LISonication improved chlorhexidine and cetylpyridinium chloride-based agents C_LI