Preliminarily Study On Biofilm Formation And Characteristics Of Brucella

Brucellosis, a zoonotic disease of global importance, is a chronic and natural focus infection disease which is caused by Brucella species. It is a potentially fatal infection that has detrimental effects on many organs. Brucellosis is widely distributed throughout the world, which often causes different extents of pandemic. The pandemic of Brucellosis not only inflicts damage on the development of animal husbandry, but also threatens human health. Biofilms are tightly packed communities of bacteria, that grow on living or inert surfaces and surround themselves with secreted polymers, which is a corresponding lifestyle of planktonic bacteria and can help bacteria adapt to adverse living enviromment. The formation of biofilm is a dynamic process, its main feature is the heterogeneity of the structure and physiology. Bacteria with biofilm can increase their resistance to external environment, hot and cold, disinfectants and antibiotics, cause persistent and repeated infection. Therefore, the basic research of biofilm has a very important clinical and practical significance.In this study, firstly, we quanified the formation of biofilm by using 96-well plates and determine the best incubation time of bacteria by dying crystal violet(CV). The results showed that it could form the more mature biofilm on the sixth day. Then we used the tube method, microscopy and scanning electron microscopy to observe Brucella biofilm. The results showed that:it can easily form biofilm in the interface of gas and liquid, and can be clearly seen by crystal violet staining; Biofilm structure could be observed under ordinary microscope; During adhension, the bacteria began to gather to form colonies, only a small amount of extracellular polymeric package were observed under electron microscopy, but no mature biofilms were found. With the growth of bacteria, large amounts of extracellular matrix was secretion and adhered closely, and the biofilm structure became thicher. Mature biofilm structure is more complex. Under scanning electron microscopy, we found that flakes or clustered colonies were wrapped together with mucus secreted by the bacteria themselves and formed a dense membrane-like structure. Between bacteria, nutrients, the flow moisture and structure of the exchange channel could be observed, and some mucus were also found.In addition, Minimum bacteriacidal concentration(MBC) of streptomycin sulfate, moxifloxacin, gentamycin and kanamycin was measured by use of antibiotic-sensitive of Brucella. First, we induced bacterial biofilm to form by using 96-well cell culture plate, and then measured MBC of antibiotic on biofilm state of bacteria. By comparison, the MBC of the four kinds of antibiotics moxifloxacin, planktonic bacteria states are the lowest, and streptomycin sulfate for two states of bacteria are the highest. In clinical, applicate these four kinds of drugs in the treatment infection of Brucella, it should be choice of moxifloxacin firstly. Four kinds of antibiotics on biofilm state of Brucella MBC were higher than that of planktonic state showed that the biofilm formation of Brucella was an important factor in its resistance...