The patient was initiated on IV Ceftriaxone, a

third-generation cephalosporin, which provides robust coverage against

Streptococcus pneumoniae. Based on the structure-activity relationship (SAR) of

cephalosporins, what specific functional groups on the C-7 side chain

characterize third- generation agents like ceftriaxone, and how do these

chemical features ensure therapeutic efficacy in severe respiratory infections?