Lecture 10 Flashcards
What drug is known as the last resort antibiotic?
-Colistin
-Used to treat infections caused by multi-drug resistant Gram negative bacteria
Potential issues with drug therapy?
-Drug delivery
-Drug retention
-Correct activity spectrum
-Toxic side effects
-Development of resistance
What is antimicrobial chemotherapy?
It is the drug treatment of parasitic infections in which the parasite are destroyed or removed without injuring the host.
Who developed antimicrobial chemotherapy
Paul Ehrlich (1854-1915)
What is penicillin
-A B-lactan antibiotic that inhibits the formation of peptidoglycan cross-links in the bacterial cell wall
-Discovered by Alexander Fleming (1928)
Problems with antimicrobial drugs:
-Opportunistic infection
-Allergic reactions
-Treatment failure
Relationship between human and microorganism is affected by what factors?
-Natural distribution of microorganism
-Microbial pathogenicity
-Susceptibility to infection
Difference between bacteriostatic and bactericidal
Bacteriostatic- stop the growth of bacteria e.g Chloramphenicol
Bactericidal- kill bacteria e.g penicillin
Different sites in target organism and the drug that affect them
Cell wall-penicillin
Cytoplasmic membrane-Polynenes
Protein synthesis- Choramphenical
Nucleic acid metabolism- Rifampicin
Spectrum of antimicrobial activity:
Narrow spectrum drug- penicillin
Broad spectrum drug- tetracyclines
What is Penicillin G?
-Also known as Benzyl-penicillin
-Obtained from mold fungi Penicillium notatum
-Disrupts cell wall synthesis by inhibiting Transpeptidase
Disadvantages of Penicillin G:
-Cleaves B-lacran ring by gastric acid
-Cleaves B-lactan ring by bacterial enzymes (beta-lactamases)
-Narrow anti-bacterial spectrum
Other penicillin derivatives
-Penicillin V (has resistance to acid)
-Oxacillin ( penicillinase resistance)
-Amoxicillin (extends activity spectrum)
Methods used to determine the level of antimicrobial activity:
- Mueller- Hinton broth dilution susceptibility assay
- Kirby Bauer Fisk diffusion assay
