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Antiobiotics
Microbiology Block
33
Medical
08/15/2010

Additional Medical Flashcards

 


 

Cards

Term

Amikacin

1. Mechanism of Action

2. Resistance

Definition

2. Antibiotic target site: ribosome. Mechanism of plasmid resistance: interference with transport into the cell. Plasmid product: enzyme for O-nucleotidylation, O-Phosphorylation or N-acetylation of antibiotic.

 

Term

Aminoglycoside

1. Mechanism of Action

2. What bacteria do they affect/not affect?

3. Resistance

4. Family Members

Definition

1. Ribsome/Translation inhibitors. Aminoglycosides interact with the 16S rRNA in the 30S subunit of the ribosome, preventing the binding of f-Met (formyl-methionine), which is the 1st amino acid of most bacterial proteins.

2. Affects gram negative and gram positives but they need to respire. Requires strong PMF to get transported. Intestinal tract flora not affected

3. Resistance: inactivated by N-acetylation, O-phosphorylation, O-adenylation

4. Amikacin, Tobamycin, Gentamicin, Netimicin, Neomycin, Streptomycin

Term

Carbapenems

1. Mechanism of Action

Definition

1. Interferes with cell wall synthesis - cell wall steps

Term

Cephalosporins

1. Mechanism of Action

2. Resistance

Definition

1. Interferes with cell wall synthesis - cell wall steps, transpeptidase reaction. Highly selective.

2. Antibiotic Target Site: Cell wall. Mechanism of Plasmid Resistance: Enzymatic hydrolysis. Plasmid Product: Beta lactamase

 

Term

Chloramphenicol

1. Mechanism of Action

2. Resistance

Definition

1. Ribsome/Translation inhibitors. Interact with the 50s subunit and block the formation of the peptide bond. Inhibit chain elongation.

2. Can be inactivated by acetylation

Term

Ciprofloxacin (Quinolone)

1. Mechanism of Action

Definition

 

1. Interfere with DNA replication - blocks DNA gyrase

 

Term

Clindamycin

1. Mechanism of Action

2. Resistance

Definition

1. Inhibit chain elongation, binds to 50s.

2. Resistance - Target site: Ribosome 50S. Mechanism of Resistance: Modification of 23S RNA Plasmid Product: Methylase

Term

D-cycloserine

1. Mechanism of Action

Definition

1. Interferes with cell wall synthesis - cytoplasmic steps. Blocks ala racemase.

Term

Erythromycin (Macroslides)

1. Mechanism of Action

2. Resistance

3. Family Members

Definition

1. Ribsome/Translation inhibitors. Interact with the 23S rRNA in the 50s subunit and cause the release of the growing peptide chain. 

2. Target site: Ribosome 50S. Mechanism of Resistance: Modification of 23S RNA Plasmid Product: Methylase. Methyltransferases do this.

3. Aithromycin, clarithromycin, ditrithromycin, troleandomycin

 

Term

Floroquinolones

(Sparfloxacin, ofloxacin, enoxacin, lomefloxacin, trovafloxacin, levofloxacin)

Definition
Spectrum: interfere with DNA replication - DNA gyrase
Term
Gentamicin
Definition

 

Resistance - Antibiotic target site: ribosome

Mechanism of plasmid resistance: interference with transport into the cell

Plasmid product: enzyme for O-nucleotidylation, O-Phosphorylation or N-acetylation of antibiotic

 

Term
Grepafloxacin
Definition

Mode of action: interfere with DNA replication - DNA gyrase

Term
Kanamycin
Definition

Resistance - Antibiotic target site: ribosome

Mechanism of plasmid resistance: interference with transport into the cell

Plasmid product: enzyme for O-nucleotidylation, O-Phosphorylation or N-acetylation of antibiotic

Term

Lincosamides

Ex: lincomycin, clindamycin, chloramphenicol

Definition

Spectrum: Ribsome/Translation inhibitors. Interact with the 50s subunit and block the formation of the peptide bond.

Resistance: methylation of subunits in the ribosome

Term

Metronidazole

1. Mechanism of Action

Definition

1. Inhibits DNA synthesis. It causes breaks in DNA

Term
Monobactams
Definition
Spectrum: Interferes with cell wall synthesis
Term
Oxazolidinones - Zyvox (Linezolid)
Definition
Spectrum: Ribsome/Translation inhibitors. Oxazolidinones prevent formation of f-met:mRNA:30s subunit tertiary complex. Active against MRSA, VRE and multiresistant S. Pneumoniae
Term

Penicillin

1. Mechanism of Action

2. Resistance

3. Solution to Resistance

Definition

1.Works by inhibiting PBP during cell wall synthesis - transpeptidase reaction. Bacteriocidal. Highly sellective. Lipophilic - can pass through gram - bacterial membrane. Procaine and bezathine, penicillin G are highly insoluble, they slowly diffuse into the blood and become Na Penicillin. This allow us to reach therapeutic level.

2. Antibiotic Target Site: Cell wall. Mechanism of Plasmid Resistance: Enzymatic hydrolysis. Plasmid Product: Beta Lactamase - inactivates penicillin by cleaving the beta lactam ring. Works in gram+ and - bacteria.

3. Inhibitors of beta lactamase can be administered with penicillin. Ex: Clavulanate-amoxicillin = augmentin, clauvenate-ticarcillin = timentin, sulbactam-ampicillin = unasyn, tazobactam-piperacillin = zocin

Problem: Extended spectrum beta lactamases: can cleave most drugs including methicillin

Term
Phosphonomycin (Fosfomycin)
Definition

 

Spectrum: Interferes with cell wall synthesis - cytoplasmic steps

Resistance: it is cleaved by fosfomycinases

 

Term

Polymycin

1. Mechanism of Action

2. Uses

Definition

1. Interferes with cell membrane. It's a polypeptide antibiotic that forms pores - bind to phosphatidyl ethanolamine rich areas of the membrane. It is highly toxic, especially in the kidney.

2. Mostly on skin

Term
Quinolones
Definition
Spectrum: Inhibits DNA synthesis. Inhibit DNA gyrase that prevents DNA relaxation for transcription
Term

Rifampin

1. Mechanism of Action

2. Resistance

Definition

1. Inhibits DNA synthesis. Binds RNA polymerase to prevent transcription

2. Changes in RNA polymererase prevent interaction of antibiotic with RNA

Term
Rifamycin and Rifampin
Definition
Spectrum: interfere with DNA dependent RNA polymerase
Term
Spectinomycin
Definition

 

Resistance - Antibiotic target site: ribosome

Mechanism of plasmid resistance: block transport into cell

Plasmid product: O nucleotidylation - adenylation or O-phosphorylation of antibiotic

 

Term
Streptogramins
Definition

Spectrum: Ribsome/Translation inhibitors. Bind 50s subunit and block translocation of the peptide chain to the E(P) site.

Resistance: methylation of the ribosomal subunit

Term

Streptomycin

1. Mechanism of Action

2. Resistance

Definition

1. Bind and block 30s subunit blocking protein synsthesis. Bactericidal.

2.  Antibiotic target site: ribosome. Mechanism of plasmid resistance: block transport into cell. Plasmid product: O nucleotidylation - adenylation or O-phosphorylation of antibiotic.

 

Term

Sulfonamides

1. Mechanism of Action

2. Resistance

3. Family Members

Definition

1. Inhibits DNA synthesis by inhibiting dihydropteorate synthetase. It ia a PABA analog that inhibits folic acid synthesis. (PABA binds to this enzyme). It is bacteriostatic.

2. Via metabolic bypass, the creation of new enzymes or mutation of existing enzymes (like the one above) that prevent antibiotic from working 

3. Trimethorprim: inhibits dihydrofolate reductase. Can be combined with Sulfonamide - ex: bactrim, it is now bactericidal. 

Term

Tetracycline

1. Mechanism of Action

2. Resistance

2. Family Members

Definition

1. Ribsome/Translation inhibitors. Interact with the 16srRNA portion of the 30s ribosomal subunit and block the transfer of tRNA into the acceptor site. Bacteriostatic.

2. Mechanism of plasmid resistance: pumps antibiotic out. Plasmid product: inducible membrane proteins

3. Oxytetracycline, Deocycycline, Demeclocycline

Term
Tobramycin
Definition

 

Resistance - Antibiotic target site: ribosome

Mechanism of plasmid resistance: interference with transport into the cell

Plasmid product: enzyme for O-nucleotidylation, O-Phosphorylation or N-acetylation of antibiotic

 

Term

Trimethoprim

1. Mechanism of Action

2. Resistance

Definition

1. Inhibits DNA synthesis. Inhibits dihydrofolate reductase, therefore inhibitting folic acid synthesis. Bacteriostatic. Bactericidal when combined with sulfonamides.

2. Via metabolic bypass, that is the creation of new enzyme or mutation on existing enzymes (like the one above), prevent antibiotic from working

Term

Vancomycin (glycopeptide)

1. Mechanism of Action

2. Resistance

Definition

1. Interferes with bacterial cell wall formation - wall steps, bind to D-Ala-D-Ala

2. Vancomycin resistant enterococci (VRE) - Modifies D-Ala to either D-Ser or D-Lac so that vancomycin is cannot bind here.

Term

Bacitracin

1. Mechanism of Action

Definition

1. Block early steps in cell wall synthesis

Term

Neomycin

1. Mechanism of Action

Definition

1. Binds to 30s subunit preventing protein synthesis