1. Amoxicillin works by inhibiting cell wall synthesis during the stage of active multiplication and is a broad spectrum drug. The organisms that we tested with Amoxicillin, both Gram + & - were all resistant to this drug. The Zone of Inhibition was 0mm for E. Coli, S. Aureus, P. aeruginosa, S. marcescens.
2. Ampicillin’s mode of action is to penetrate Gram + and some Gram – cells. It has an Amino group which helps it to penetrate the outer membrane of Gram- bacteria. It inhibits bacteria from making cell walls and leads to cell lysis and is a broad spectrum drug. All bacteria that we tested, Gram -and Gram + were resistant to this drug. E.Coli was resistant to this drug, its Zone of Inhibition was 0mm. S. Aureus was resistant to this drug, its Zone of Inhibition was 8mm. P.Aeruginosa was resistant to this bacteria, its Zone of Inhibition was 0mm. S.marcescens was resistant to this drug, its Zone of Inhibition was 0mm.
3. Cephalothin’s mode of action is to prevent cell wall synthesis and is narrow spectrum. E.coli was resistant to this drug. Its Zone of Inhibition was 11mm. S. aureus was sensitive to this drug. Its Zone of Inhibition was 34mm. P.aeruginosa was resistant to this drug. Its Zone of Inhibition was 0mm. S. marcescens was resistant to this drug. Its Zone of Inhibition was 0mm. Gram + bacteria: S.aureus was sensitive to this drug. Gram – bacteria: E.coli, P.aeruginosa, and S.marcescens were resistant to this drug.
4. Erythromycin’s mode of action is to inhibit protein synthesis by binding to 50s ribosomal subunits. This drug can be bactericidal or bacteriostatic depending on organism and drug concentration and is narrow spectrum. Gram - E.coli was resistant to this drug, its Zone of Inhibition was 8mm. Gram + S.aureus was sensitive to this drug, its Zone of Inhibition was 24mm. Gram - P.aeruginosa was resistant to this drug, its Zone of Inhibition was 0mm. Gram - S.marcescens had an Intermediate response to this drug, its Zone of Inhibition was 17mm.
5. Neomycin’s mode of action is to inhibit protein synthesis by binding to the 30s ribosomal subunit and is a broad spectrum drug. Gram negative E.coli had an Intermediate response to this drug, its Zone of Inhibition was 13mm. Gram positive S.aureus was resistant to this drug, its Zone of Inhibition was 12mm. Gram negative P.aeruginosa was resistant to this drug, its Zone of Inhibition was 8mm. Gram negative S.marcescens had an Intermediate response to this drug, its Zone of Inhibition was 16mm.
6. Streptomycin’s mode of action is to inhibit protein synthesis by binding to the 30s subunit. It inhibits both Gram + and Gram- bacteria. It is a broad spectrum antibiotic. Gram negative E.coli was sensitive to this drug, its Zone of Inhibition was 15mm. Gram positive S.aureus was sensitive to this drug, its Zone of Inhibition was 14mm. Gram negative P.aeruginosa was resistant to this drug, its Zone of Inhibition was 11mm. Gram negative S.marcescens was resistant to this drug, its Zone of Inhibition was 11mm.
7. Sulfamethoxazole’s mode of action is to inhibit nucleic acid replication. This drug is bacteriostatic and is broad spectrum. Gram negative E.coli was sensitive to this drug, its Zone of Inhibition was 18mm. Gram positive S.aureus was sensitive to this drug, its Zone of Inhibition was 17mm. Gram negative P.aeruginosa was resistant to this drug, its Zone of Inhibition was 0mm. Gram negative
