<prompt> Answer this question truthfullyWhich gram-negative bacterial species are targeted by 2nd generation cephalosporins?  <response>: <reason> 2nd generation cephalosporins are effective against a range of gram-negative bacterial species including H. influenzae, Enterobacter aerogenes, Neisseria spp., Serratia marcescens HENS as well as Proteus mirabilis, E. coli, and Klebsiella pneumoniae PEcK. 