antibacterial chemotherapy

[blank_start]Chemotherapeutics[blank_end] prepared synthetically in the lab

Antibiotics are [blank_start]by-products[blank_end] of [blank_start]metabolic activity[blank_end] of bacteria and fungi

Classification of antibacterial agents A- According to spectrum: 1- [blank_start]Narrow[blank_end] spectrum 2- [blank_start]Broad[blank_end] spectrum

Classification of antibacterial agents B- According to the antibacterial effect 1- [blank_start]Bacteriostatic[blank_end] 2- [blank_start]Bactericidal[blank_end]

Classification of antibacterial agents C- According to mechanism of action: 1- Inhibition of [blank_start]cell wall synthesis[blank_end] 2- Inhibition of [blank_start]cell membrane function[blank_end] 3- Inhibition of [blank_start]protein synthesis[blank_end] 4- Inhibition of [blank_start]nucleic acid synthesis[blank_end] 5- Inhibition of [blank_start]bacterial metabolism[blank_end]

Target receptor for Inhibition of cell wall synthesis

2 groups for Inhibition of cell wall synthesis 1. [blank_start]B lactam[blank_end] drugs 2. [blank_start]Vancomycin[blank_end] & [blank_start]bacitracin[blank_end]

β Lactam drugs

Penicillins & cephalosporins inhibit early precursors in transpeptidation

[blank_start]Vancomycin[blank_end] & [blank_start]bacitracin[blank_end] inhibit early precursors in transpeptidation

advantage of β Lactam drugs

bacitracin act only on growing cells

Inhibition of cell membrane function drugs

Advantages of polymyxins & polyenes 1. [blank_start]Bactericidal[blank_end] 2. [blank_start]can act on non growing cells[blank_end] Disadvantage of polymyxins & polyenes 1. [blank_start]Toxic effects on kidney & CNS[blank_end]

Drugs acting on the 30S ribosomal subunit

Aminoglycosides 1.[blank_start]Amikacin[blank_end] 2. [blank_start]Gentamicin[blank_end]

Tetracyclines effective in treatment of Chlamydophila

oleandomycin is effective in treatment of intracellular bacteria

Tetracyclines: Effective in treatment of intracellular bacteria e.g. [blank_start]Chlamydophila[blank_end] & [blank_start]Brucella[blank_end]

Aminoglycosides are [blank_start]Bactericidal[blank_end]

Tetracyclines are [blank_start]Bacteriostatic[blank_end]

Drugs acting on the 50S ribosomal subunit except

Drugs acting on the 50S ribosomal subunit are [blank_start]Bacteriostatic[blank_end]

Macrolides 1. [blank_start]Erythromycin[blank_end] 2. [blank_start]oleandomycin[blank_end]

Inhibition of nucleic acid synthesis 1. [blank_start]Rifampin[blank_end] 2. [blank_start]Quinolones[blank_end]

Rifampin: inhibit [blank_start]DNA dependent RNA polymerase[blank_end]

Quinolones: inhibit [blank_start]DNA gyrase[blank_end]

[blank_start]Rifampin[blank_end]: inhibit DNA dependent RNA polymerase

Inhibition of bacterial metabolism 1. [blank_start]Sulphonamides[blank_end] 2. [blank_start]Trimethoprim[blank_end]

Sulphonamides: inhibit [blank_start]DHFA synthetase[blank_end]

Trimethoprim: inhibits [blank_start]DHFA reductase[blank_end]

Trimethoprim: inhibits DHFA synthetase

Bacterial Resistance to chemotherapeutic agents 1. [blank_start]Non genetic origin[blank_end] (natural/inherent) 2. [blank_start]Genetic origin[blank_end] (acquired)

Genetic origin ([blank_start]acquired[blank_end]) is [blank_start]Unpredictable[blank_end]

Genetic origin ([blank_start]acquired[blank_end]) [blank_start]Unpredictable[blank_end] 1- [blank_start]Chromosomal[blank_end] ([blank_start]Mutation[blank_end]=change in [blank_start]receptor[blank_end]) 2- [blank_start]Extrachromosomal[blank_end] ([blank_start]R factor[blank_end] carrying destroying enzymes

Non genetic origin ([blank_start]natural[blank_end]/inherent) [blank_start]Innate[blank_end], [blank_start]predictable[blank_end] 1- Absence of cell wall ([blank_start]Mycoplasma[blank_end]) 2- Permeability barrier in cell envelope ([blank_start]Pseudomonas[blank_end]) 3- Non multiplying ([blank_start]TB[blank_end])

Mechanisms of Resistance 1. [blank_start]Drug Inactivation[blank_end] 2. [blank_start]Change of Permeability[blank_end] 3. [blank_start]Alter Target Structure[blank_end] e.g.[blank_start]PBP[blank_end]s, [blank_start]30S[blank_end], [blank_start]50S[blank_end] 4. [blank_start]Alter Metabolic Pathway[blank_end] ([blank_start]utilize preformed FA[blank_end])

[blank_start]Cross Resistance[blank_end] Bacteria resistant to a drug may be resistant to a [blank_start]chemically related[blank_end] one.

Antibacterial Drug Combinations 1- [blank_start]Indifference[blank_end] ( 1 + 1= 1 ) 2- [blank_start]Addition[blank_end] (1 + 1 = 2 ) 3- [blank_start]Synergism[blank_end] ( 1 + 1= 3 ) 4- [blank_start]Antagonism[blank_end] ( 1 + 1= 0 )

Synergism [blank_start]Penicillin[blank_end] + [blank_start]aminoglycoside[blank_end] [blank_start]Carbenicillin[blank_end] + aminoglycoside [blank_start]Ampicillin[blank_end] + [blank_start]Metronidazole[blank_end]

Control of Drug Resistance 1- Give only when [blank_start]indicated[blank_end] 2- Proper choice (according to [blank_start]susceptibility[blank_end]) 3- Give in the proper [blank_start]dose[blank_end] for proper [blank_start]time[blank_end] (To prevent [blank_start]selection pressure[blank_end]) 4- Use drug [blank_start]combinations[blank_end] (simultaneous use of 2 drugs) 5- Avoid [blank_start]abuse[blank_end] of [blank_start]valuable[blank_end] drugs