Reduction of Acinetobacter baumannii biofilm formation by natural zeolite

Acinetobacter baumannii is an emerging human pathogen. Biofilm formation is an important virulence factor which contributes to the pathogenesis of A. baumannii, but data regarding the isolates recovered from the natural environment are missing. The biofilm formation at the solid-liquid/air-liquid interfaces of environmental isolates of A. baumannii, as well as the influence of natural zeolitizied tuff (NZ) on its formation was determined. In total, 24 environmental isolates of A. baumannii (14 multi-drug resistant, 10 sensitive to antibiotics) were recovered from different stages of the secondary type of municipal wastewater treatment plant. Isolates sensitive to antibiotics were statistically significantly more hydrophobic and formed stronger biofilm than multi-drug resistant isolates. Biofilm formation was significantly positive correlated with hydrophobicity of cells. Biofilm formation at solid-liquid interface was significantly inhibited by the addition of 1% of NZ into the growth medium due to the immobilization of bacterial cells onto the NZ particles. Biofilm formation at air-liquid interface was inhibited only by the addition of 10% of NZ. NZ could find application in control of the biofilm formation of this pathogen on abiotic surfaces.