Antibiotics Flashcards
Antibiotic
Chemical substance produced by a microorganism that inhibits growth of or kills other microorganisms
Ex. Streptomycin
Gentamicin
Antimicrobial Agent
Chemical substance derived rom a biological source or produced by chemical synthesis that kills or inhibits the growth or microorganism
Ex. Sulfonamide
Enrofloxacin
When do you use an antibiotic
- When the bodies normal defenses cannot prevent or overcome disease
- Antimicrobials must act without damaging the host cells
- Disinfectants and antiseptics act outside the host
Penicillin
Alexander Fleming-> Domagk->1935
Sulfonamides
Broad spectrum-> Domagk->1935
Natural (true antibiotics)
-Fungal and bacterial sources
Ex. Benzyl Penicillin, gentamicin, streptomycin, chlortetracycline
Semi-Synthetic antibiotics
-Chemically altered natural compound
Ex. Ampicillin, Amikacin
Synthetic antibiotics
-Chemically designed in the lab
Ex. Sulfonamide, enrofloxacin, marbofloxacin
Antibiotic Classifications
- Chemical family structure
- Mode of action
- Type of antimicrobial activity
- Spectrum of antibacterial activity
Mode of action
- Inhibitors cell wall synthesis
- Inhibitors of protein synthesis
- Inhibitors of nucleic acid synthesis
- Inhibitors of membrane function
- Anti-metabolites
Inhibitors of Cell wall synthesis
- Penicillins
- Cephalosporins
- Vancomycin
- Bacitracin
- Cycloserine
- Monobactums
- Carbapenems
Inhibitors of protein synthesis
- Chloramphenicol
- Erythromycin
- Tetracyclines
- Streptomycin
Inhibitors of nucleic acid synthesis
- Quinolones
- Rifampin
Inhibitors of plasma membrane
-Polymixin B
Inhibition of essential metabolite synthesis
- Sulfonamide
- Trimethoprim
Cell wall synthesis inhibitor antibiotics
Beta Lactam antibiotics
-Penicillin and Cephalosporins
-Inhibit peptidoglycan synthesis
-binds and inhibits penicillin binding proteins
Beta lactamase-enzymes present in bacteria with can please the beta lactam ring and inactivate penicillin
*cluvulanic acid- prevents degradation of penicillin by beta lactamase
Glycopeptides
Vancomycin and Daptomycin
Last drug of choice for some gram positive bacteria because of resistance.
Protein synthesis inhibitor antibiotics
Aminoglycosides Gentamicin, amikacin, kanamycin, streptomycin -Inhibits 30s subunit of bacterial ribosomes Tetracyclins Oxytetracyclin, Chlorotetracyclin -Inhibits 50s subunit of bacterial ribosomes Macrolides Erythromycin -Inhibits 50s subunit Lincosamides Clindamycin -Inhibits 50s subunit Phenocols Chloramphenicol -Inhibits 50s subunit
DNA synthesis inhibitor antibiotics
Quinolones Nalidixic acid, ciprofloxacin -Inhibits enzyme DNA gyrase Metranidazole Makes breaks in the DNA Rifampin -Inhibit RNA polymerase -Active against Mycobacterium tuberculosis Mupirocin -Inhibit tRNA synthetase -Commonly used for MRSA
Membrane function inhibitor antibiotics
Polymixins
Daptomycin
Folic acid synthesis inhibitor antibiotics (anti-metabolites)
Sulfonamides
Trimethoprim
competitive inhibitors
Bacteriostatic Activity
Inhibition of bacterial multiplication/growth
MIC
Minimal inhibitory concentration- Lowest drug concentration that completely INHIBITS bacterial growth
Bactericidal Activity
Killing effect on a bacterial population
MBC
Minimal bactericidal concentration -Lowest drug concentration that KILLS the population
Bactericidal Drugs
KILLS
- aminoglycosides
- Beta lactams
- clindamycin
- metranidazole
- quinolones
- Rifampin
- Sulfonomide/dipyrmidine
- Vancomycin
Bacteriostatic Drugs
INHIBITS GROWTH
- Chloramphenicol
- Clindamycin
- Lincosamides
- Macrolides
- Sulfonomides
- Tetracyclines
- Tylosin
Broad Spectrum Antibiotics
Antibiotics active against a wide variety of bacteria
Ex. Tetracycline
Narrow Spectrum Antibiotics
Only a narrow range
Ex. Penicillin
Susceptibility Results
S- High likelihood of therapeutic SUCCESS
I- Uncertain outcome
R- High likelihood of therapeutic FAILURE
Horizontal Gene Transfer
Lysogenic conversion -Bacteriophage DNA into a bacterial cell Transduction -Bcterial DNA into another bacteria via phage Conjugation (plasmids) Transformation (uptake of exogenous DNA)
Transposon
Chunks of DNA that can move through plasmid
-may contain virulence or resistance factors
Innate Resistance
Pre-exisitng property
Acquired Resistance
- New genetically encoded trait not representative of the species
- Mutations
- Horizontal gene transfer
Examples of natural resistance
- Enzymatic destruction or inactivation of drugs (beta lactamase)
- Prevention of penetration to target sites within microbe
- Alteration of drug target site
- Rapid efflux of antibiotics
