The present invention provides a method for the treatment and/or prevention of bacterial infection caused by Enterobacteriaceae bacteria in central nervous system and/or peripheral blood circulation in a mammal by administering effective amount of outer membrane protein A (OmpA) or its derivatives to a mammal. Also provided are a method for vaccinating a mammal to produce an antibody against bacterial infection caused by Enterobacteriaceae family in central nervous system and/or peripheral blood circulation and a method of detecting or diagnosing bacterial infections caused by Enterobacteriaceae family in central nervous system and/or peripheral blood circulation in a mammal. An antibody and a kit on the basis of the vaccinating method and detecting/diagnosing method are also provided.