C9 - Antimicrobials Flashcards
chemical substances produced by microorganisms with the capacity to inhibit (bacteriostatic) or kill (bactericidal) other microorganisms
can also be synthesized by means of chemical procedures that are independent from microbial activity
ANTIBIOTICS
Antibiotics examples
Bacitracin
Polymyxin
Cephalosporins
Gentamicin
Penicillin
Erythromycin
Neomycin
Amphotericin B
Nystatin
Chloramphenicol
Source of Bacitracin
Bacillus subtilis
Source of Polymyxin
Bacillus polymyxa
Source of Cephalosporins
Cephalosporium
Source of Gentamicin
Micromonospora purpurea
Source of Erythromycin
Streptomyces erythraeus
Source of Penicillin
Penicillium notatum
Source of Amphotericin B
Streptomyces nodosus
Source of Nystatin
Streptomyces noursei
Source of Neomycin
Streptomyces fradiae
Source of Chloramphenicol
Streptomyces venezuelae
antimicrobial agents that inhibit bacterial
growth but generally do not kill the organism
BACTERIOSTATIC AGENTS
agents that usually kill target organisms
BACTERICIDAL AGENTS
Generally Bacteriostatic agents
Chloramphenicol
Erythromycin and other macrolides
Clindamycin
Sulfonamides
Trimethoprim
Tetracyclines
Tigecycline
Linezolid
Quinupristin/dalfopristin
Generally Bactericidal agents
Aminoglycosides
ẞ-lactams
Vancomycin
Daptomycin
Teicoplanin
Telavancin
Quinolones (e.g., ciprofloxacin, levofloxacin)
Rifampin
Metronidazole
effective against limited number of pathogens
Narrow-Spectrum
Narrow-Spectrum antimicrobials
bacitracin,
clindamycin,
dapsone,
erythromycin,
isoniazid,
penicillin,
polymyxin B and
vancomycin
destroys different kinds of organisms
Broad-Spectrum
Broad-Spectrum examples
ampicillin,
cephalosporins,
chloramphenicol,
ciprofloxacin,
rifampicin,
sulphonamides,
trimethoprim and
tetracyclin
Classification of Antibacterial Drugs
- Natural Drugs
- Semi-synthetic Drugs
- Synthetic Drugs
produced by bacteria and fungi
Natural Drugs
Natural Drugs examples
amphotericin B,
erythromycin,
kanamycin,
neomycin,
nystatin,
rifampicin,
streptomycin,
tetracyclin,
vancomycin,
bacitracin,
gentamicin,
polymyxin,
griseofulvin,
penicillin and
cephalosporin
modified natural drugs with added chemical group
Semi-synthetic Drugs
Semi-synthetic Drugs Examples
ampicillin,
carbenicillin and
methicillin
chemically produced drugs
Synthetic Drugs
Synthetic Drugs Examples
sulphonamides,
trimethoprim,
chloramphenicol,
ciprofloxacin and
dapson
MODE OF ACTION OF ANTIBACTERIAL AGENTS
A. Inhibitors of Cell Wall Synthesis
B. Protein Synthesis Inhibitors
C. Nucleic Acid Synthesis Inhibitors
D. Cell Membrane Inhibitors
E. Essential Metabolite Inhibitors
most selective with a high therapeutic index
inhibit the activity of the transpeptidase enzymes in which cell growth stops and death of the cell often follows
Inhibitors of Cell Wall Synthesis
Inhibitors of Cell Wall Synthesis examples
β-Lactam (Beta-Lactam)
Vancomycin
Bacitracin
Isoniazid
Cephalosporins
Penicillinase-resistant penicillin drugs
Carbenicillin
inhibits transpeptidation and cell wall synthesis
β-Lactam (Beta-Lactam)
β-Lactam (Beta-Lactam) examples
penicillins,
cephalosporins,
carbapenems and
monobactams
inhibits translocation and elongation of
peptidoglycan layer
Vancomycin
inhibits synthesis of peptidoglycan precursors
Bacitracin
acts only on growing cells and can either be bactericidal or bacteriostatic
Isoniazid
Cephalosporins examples
cephalothin,
cefoxitin,
ceftriaxone,
cephalexin,
cefixime and
cefoperazone
Penicillinase-resistant penicillin drugs examples
methicillin,
nafcillin and
oxacilin
binds with 30S subunit that results in the misreading of mRNA and thus interferes with aminoacyl-tRNA binding
also binds with 50S subunit that results in the inhibition of peptidyl transferase and peptide chain elongation
Protein Synthesis Inhibitors
Protein Synthesis Inhibitors Examples:
Binds to 30S
aminoglycosides(gentamicin),
kanamycin,
neomycin,
streptomycin,
tobramycin),
tetracyclins,
spectinomycin
mioglycosides
Protein Synthesis Inhibitors Examples:
Binds to 50S
chloramphenicol,
erythromycin,
lincomycin and
clindamycin
blocks the initial step in protein synthesis
Linezolid
C. Nucleic Acid Synthesis Inhibitors examples
Rifampicin
Quinolone
Metronidazole
inhibits RNA polymerase
Rifampicin
interferes with DNA gyrase and topoisomerase IV and highly effective for enteric bacteria (e.g, E.coli)
Quinolone
Quinolone examples
ciprofloxacin,
norfloxacin and
levofloxacin
disrupts DNA and effective against anaerobic bacteria
Metronidazole
D. Cell Membrane Inhibitors
Polymyxin B and E
for gram(-) bacteria (e.g., Pseudomonas aeruginosa) and as topical antibiotic
Polymyxin B and E
Essential Metabolite Inhibitors examples
Sulfamethoxazole (SMZ)
Trimethoprim (TMP)
Dapsone
Isoniazid
inhibits folic acid metabolism and has a high therapeutic index
Sulfamethoxazole (SMZ)
blocks tetrahydrofolate synthesis
Trimethoprim (TMP)
interferes with folic acid synthesis
Dapsone