<prompt> Answer this question truthfullyWhat are the names of the first generation cephalosporins that can be used to treat skin and soft tissue infections caused by Staphylococcus and Streptococcus?  <response>: <reason> Cephalexin and cefazolin are the first generation cephalosporins that can be used to treat skin and soft tissue infections caused by Staphylococcus and Streptococcus. 