Mechanism of action of common antibiotics

Betalactams (e.g. penicillins and cephalosporins): Inhibit cell wall synthesis.

Fluoroquinolones (e.g. ciprofloxacin and nalidixic acid): Bind to bacterial DNA gyrase and topoisomerase IV, interfering with bacterial DNA synthesis.

Tetracyclines: Bind to the bacterial 30S ribosome, inhibiting bacterial protein synthesis.
Aminoglycosides (e.g. gentamicin): Bind to 30S ribosome unit as well.

Macrolides (e.g. azithromycin): Reversibly bind to the 50S ribosomal subunit.

Sulfonamides (e.g. sulfamethoxazole): Inhibit steps in bacterial folic acid synthesis.

This stuff is high yield for Step 1.