An increasing number of bacteria have been described as benefiting from interaction with free-living amoeba. The most common association between free-living amoeba and microorganisms is interaction of various non-pathogenic and pathogenic bacterial species with amoeba. Various pathogenic bacterial species have capacity to resist digestion by free-living amoeba, which has been observed by many researchers. Also, several of these pathogens are able to resist digestion by macrophages. In addition, free-living amoeba have been associated with several diseases in humans.