Penicillin and streptomycin in ethanol mist against spore-forming Bacillus bacteria isolated from surfaces of historical objects

Abstract

The objective of the study was to investigate the antimicrobial efficacy of ethanol mist enriched with penicillin and/or streptomycin and to examine its effects on the surface properties of model and historical textile materials from the collections of the Auschwitz-Birkenau State Museum (ABSM) in Oświęcim (Poland). Bacillus bacteria, which inhabited historical textile objects in the ABSM, were inoculated onto samples of textiles. Then, penicillin and/or streptomycin suspended in water or ethanol were applied in the form of mist. Sensitivity of the bacterial strains to the antibiotics was tested with disk diffusion (vegetative forms) and agar imprint (spores) methods. After that, surface alterations were analysed using SEM, confocal microscopy and XPS techniques. Even though initial effectiveness of presented disinfection method was observed, both for cells and spores, it resulted only in a temporary inhibition of the growth of tested bacteria. Importantly, subsequent analyses revealed that this treatment did not induce any detectable alterations in the surface morphology or chemistry of the textile materials. The developed method of applying antibiotics together with ethanol mist to increase effectiveness of ethanol against spore-forming bacteria is non-destructive and preserves the original structural and chemical integrity of historical fabric. However, the method has a biostatic effect on spore-forming Bacillus, not biocidal, so the addition of tested antibiotics does not allow the desired effect to be achieved. Nevertheless, ethanol in the form of mist without additives is biocidally effective against a wide range of microorganisms.