First generation cephalosporins have activity against staphylococcus and streptococcus, along with Proteus, E. coli, and Klebsiella. In addition to the above mentioned organisms, the second generation cephalosporins also have H. influenza activity, while the third generations have greatly expanded gram negative coverage. Note the diminished gram positive coverage as gram negative ability improves with each successive generation of cephalosporins. Because of this relationship, first generation cephalosporins are useful in treating skin and urinary infections but arenít used routinely in the treatment of AOM. Go to Generations for a breakdown of commonly prescribed cephalosporins.