Effect of novel bismuth hydroxide gel presentations on surfaces contaminated with verotoxigenic Escherichia coli

Abstract

Verotoxigenic Escherichia coli (VTEC) are emerging pathogens associated with cases of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS). Contaminated food, cattle or contact with their environment are some of the problems that especially affect the food industry, the hospital and domestic environment. Because there is no specific treatment against HUS, the prevention measures and control strategies are the key tools to reduce the transmission of this pathogen. Currently, Bismuth hydroxide has been widely used as antidiarrheal but little is known about its bactericidal activity on contaminated abiotic surfaces.The aim of this work was to evaluate the effects on the viability of VTEC O157 and non-O157 strains on glass surfaces with two types of novel Bismuth hydroxide presentations, emulsion spray and aerosol.MethodsThree VTEC strains (serotypes O157:H7, O91:H21 and O26:H11) were grown in LB broth and scattered on sterile glass plates. The strains were sprayed independently with both presentations of Bismuth hydroxide gel and the effects were determined by swabbing and counting CFU on MacConkey agar plates at different times: 4 h and 24 h.ResultsAfter 4 h of incubation at room temperature, following counts were obtained in strains controls (without treatment with Bismuth): 120 CFU (O157:H7), 190 CFU (O91:H21) and 140 CFU (O26:H11). No growth was observed in plates treated with spray, while in those treated with aerosol 80 CFU were observed only in O91:H21 strain. After 24 h, following counts were obtained in strains controls: 2 CFU (O157:H7), 6 CFU (O91:H21) and no growth (O26:H11). No growth was observed in plates treated with both presentations. ConclusionsAll the strains were affected in their growth after the application of both Bismuth presentations, although the spray showed more efficiency than the aerosol at 4 h. Since that contaminated surfaces represent a risk in the food industry, Bismuth Hydroxide gel in these novel presentations is promising as disinfectant on inert surfaces.