Mechanisms Of Resistance To Antibiotics

Question 1

Mechanism of resistance to Penicillins

Answer 1

Bacterial penicillinase (β-lactamase) cleaves β-lactam ring

Question 2

Mechanism of resistance to cephalosporins

Answer 2

Changes to penicillin-binding-proteins (PBPs), which are types of transpeptidases

transpeptidases are enzymes produced by bacteria that cross-links Peptidoglycan chains to form rigid cell walls

Question 3

Mechanism of resistance to Macrolides

Answer 3

Post-transcriptional methylation of the 23S bacterial ribosomal RNA

Question 4

Mechanism of resistance to Fluroquinolones

Answer 4

Mutations to DNA gyrase (bacterial enzyme), efflux pumps which reduce intracellular quinolone concentration

Question 5

Mechanism of resistance to Tetracyclins

Answer 5

Increased efflux of the bacteria. Y plasmid-encoded transport pumps, ribosomal protection

Question 6

Mechanism of resistance to Aminoglycosides

Answer 6

Plasmid-encoded genes for acetyltransferases, adenyltransferases and phosphotransferases

Question 7

Mechanism of resistance to Sulfonamides

Answer 7

Bacteria increase synthesis of PABA, mutation to gene encoding dihydripteroate synthetase

Question 8

Mechanism of resistance to Vancomycin

Answer 8

Alteration to the terminal amino acid residues of the NAM/NAG-peptide subunits (normally alanyl-D-alanine) to which the antibiotic binds

Question 9

Mechanism of resistance to Rifampicin

Answer 9

Mutations altering residues of the rifampicin binding site on the RNA polymerase

Question 10

Mechanism of resistance to Isoniazid

Answer 10

Mutations in the KatG gene resulting reducing the ability of the catalase-peroxidase to activate the pro-drug

Question 11

Mechanism of resistance to Pyrazinamide

Answer 11

Mutations in the pncA gene encoding PZase, reducing conversion of the pro-drug