Block 9 - Week 2

Question 1

Amoxicillin

Answer 1

Beta -lactam antibiotic

Binds to PBP-1 inactivating it causing the prevention of cross linking of peptidoglycan strands inhibiting bacterial cell wall synthesis which can then cause cell lysis

Question 2

Methicillin

Answer 2

Transpeptidase inhibitor - narrow spectrum beta lactam antibiotic - inhibits bacterial cell wall synthesis via inhibiton of transpeptidase enzyme used by bacteria to cross link the peptide used in peptidoglycan synthesis in the cell wall of gram positive bacteria

Question 3

Cefuroxime

Answer 3

Transpeptidase inhibitor - bactericidal -effective against gram negative bacteria - mechanism similar to penicillin so it inhibits cell wall synthesis leading to bacterial cell lysis - cefuroxime can cross the blood brain barrier .

Question 4

Benzylpencillin

Answer 4

Transpeptidase inhibitor - Pencillin G - beta lactam antibiotic - gram papotibe organisms. - binding to Pencillin binding proteins and inhibiting bacterial cell wall synthesis . Also Inhibits bacterial autolysin inhibitor.

Question 5

Oxytetracycline

Answer 5

30s inhibitor - broad spectrum antibiotic - inhibition of bacterial cell growth by binding to the 30s ribosomal subunit which prevents amino acyl tRNA from binding to the A site of ribosomes inhibiting translation

Question 6

Erythromycin

Answer 6

Effective against only actively dividing organisms macrolide - reversible binds to the 50s S subunit of bacterial ribosomes at the donor binding site blocking translocation of peptides from the acceptor site to the donor site inhibiting protein synthesis.

Question 7

Gentamicin

Answer 7

30s/50s inhibitor - broad spectrum - gram negative bacteria - Aminoglycosides bind to the bacterial 30s ribosomal subunit inhibiting protein synthesis. - TB

Question 8

Rifampicin

Answer 8

Broad spectrum - inhibiton of DNA dependant RNA polymerase leading to a suppression of DNA synthesis and cell death. Treats mycobacterium infections

Question 9

Trimethoprim

Answer 9

Folate antagonist - treats UTI , bronchitis , binds to dihydrofolate reductase inhibiting the reduction of dyhyrdofolic acid to THF - this leads to bacterial DNA synthesis

Question 10

Sulfamethoxazole

Answer 10

Sulfonamide drug - competes with PABA in binding to dihydrofolate synthesase (inhibiton of this) and inhibiting synthesis of tetrahydrofolic acid (THF) synthesis - which is required for synthesis of purines and inhibitions inhibits bacterial growth

Question 11

Vancomycin

Answer 11

Peptidoglycan inhibitor - last resort drug -used only after other drugs have failed

Question 12

Colistin

Answer 12

Disrupts bacterial cell membrane , changing its permeability . In addition enters bacteria and precipitates cytoplasmic components mainly ribosomes - treats acute or chronic infections.

Question 13

Ciprofloxacin

Answer 13

Broad spectrum antibiotic - topoisomerase II inhibitor which is required for bacterial DNA replication , transcription , repair etc .

mechanism of action different from others hence those bacteria resistant to other antibiotics may be susceptible to these.

Question 14

Fusidic acid

Answer 14

Translocation inhibitor - used in creams and eye drops bacteriostatic antibiotic - inhibits translocation of EF-G from ribosome leading to inhibiton of protein synthesis . Also inhibits chloramphenicol acetlytranseferase enzymes