Penicillin and streptomycin are broad spectrum bacteriostatic and bacteriocidal agents effective against gram positive bacteria and gram negative bacteria. A sterile filtered antibiotic solution containing 10,000 units of penicillin and 5mg streptomycin per ml. Penicillin and streptomycin are broad spectrum bacteriostatic and bacteriocidal agents effective against gram positive bacteria and gram negative bacteria. Penicillin acts by inhibiting cell wall synthesis. Streptomycin blocks the initiation complex of protein synthesis by binding to the 30S subunit of bacterial 70S ribosome, thus interfering with the protein synthesis.