Resistance of Gram Negative Bacteria

Question 1

About

Answer 1

• Many strains are multi drug resistant
• Can have more than one resistance mechanism
• Requires use of older antibiotics because of toxicity issues

Question 2

XDR strains

Answer 2

• Extreme drug resistance like polymyxins

Question 3

Resistance due to beta lactamases

Answer 3

Ancient enzymes: main defense mechanism for gram negative nbecteria against beta lactam antibiotics: enzymes with serine in active site, and metal enzymes

Carbapanemases resistance can inactivate all types of beta lactam antibiotics and are not inhibited by clauivanic acid

Question 4

Treatment- Carapenems

Answer 4

• gram -be bacteria capable of resisting beta lactamases
• Beta lactam antibiotic
• Structure similar to penicillin

Question 5

Colistin

Answer 5

• gram negative bacteria capable of expressing carbapenemases
• Polymyxin antibiotic
• peptide antibiotic
  mixture of 2 cyclic peptides (colistin a and b) produced by fermentation of bacillus polymyxa
• that is a gram positive bacteria

limited use due to nephrotoxicity
last resort antibiotic

Question 6

Tigecycline

Answer 6

• gram negativ bacteria capable of expressing carbapenemases
• novel tetracycline class
  characterized by additional glyclamido substituent
  Overcome resistance to earlier tetracycline
  Inhibitpr bacteria protein synthesis bu binding to 30 s ribosomal subunit blocking entry to tRNAs
  it is a broad spectrum antibiotics