Antibiotics

Bacteriostatic

STop growth/reproduction but no cell killing

Bacteriocidal

Stop growth/reproduction with cell killing

Bacteriolytic

Stop growth/reproduction AND cell killing / destruction.

Antibiotic

Derived from Microorganisms used to inhibit other microorganisms

Gram Negative Bacteria

Thin Peptioglycan layer, has outer envelope

Gram Positive

Thick peptidoglycan layer, no outer envelope

Inhibits Cell Wall Synthesis

B-Lactam covalently bond to active site on Penicillin Binding Protein. Binding inhibits peptidoglycan synthesis

Antibiotic Type that inhibits cell wall synthesis

Penicillins and Cephalosporins

Alteration in Cell Membrane integrity

Alters membrane by allowing stuff in and out to kill. Ca2+ inserts into membrane, many combine to make a channel for K to leave = cell death.

Alteration in Cell Membrane integrity Drug

Daptomycin

Inhibit Ribosomes

Bind to ribosomes and inhibit them so that you cannot make proteins = vital for life.

Drugs that bind to 50s Subunit

Macrolides, Erythromycin

Drugs that bind to 30s Subunit

Tetracycline

Inhihition of Nucleic Acid Synthesis

Block DNA gyrase so that DNA cannot be replicated

Drug that inihibits DNA synthesis

Fluoroquinolones

Inhibition of Folic Acid (Vit B9 synthesis)

Inhibit folic acid synthesis which is needed for DNA synthesis.

Drugs that Block Metabolic Pathways

Sulfonamides, Trimethoprim

Resistance Method: Enzyme inactivation

Very common, B-lactamase hydrolyzes penicillins and cephalosporins

Resistance Method: Alteration of Target Site

Ribosomal Mutations, altered DNA Gyrase and Topoisomerase, modified PBPs

Resistance Method: Alter cell wall membrane permeability

Limits access of antibiotic to the receptor, low level of resistance (must be combined with another)

Resistance Method: Use of Efflux Pumps

Proteins altered to eliminate anitbiotics as fast as they enter.

Resistance Method: Alternative Metabolic Growth Requirements

Bacteria develop alternative metabolic growth requirements to evade destruction (Auxotrophy)

Resistance Method: Overproduction of Targets

PABA: Sulfonamide Resistance, B-lactamase resistant to B-lactam antibiotics

Tolerance

Antibiotic no longer kills microorganism, only inhibits growth or multiplication

Resistance

Multiplication in the presence of the antibiotic

Cause of Tolerance

Loss of Autolysin Activity

Cause of Resistance

Most likely occurs with sub-therapeutic doses

Transduction

DNA from one bacterium to another through a bacteriophage intermeidate

Conjugation

Self Transfer, ex. physical contact

Transformation

DNA from environment put into genome.

Cardiac adverse effect from antibiotics

Prolonged QTC interval

Antibiotic effects on Oral contraceptives

Decreases efficacy

Antibiotic effects on Anti-coagulants

Increase effect of Warfarin by decreasing Vit. K

Can you use tetracyclines during pregnancy?

No, MCAT Not safe during pregnancy

-illin suffix

Penicillin

Cef- Prefix

Cephalosporins

First Gen cephalosporins attack what?

Gram Positive

Future generation cephalosporins attack what?

Gram Negative

Drug interactions for Cephalosporin

Loop diuretics can cause nephrotoxicity, alcohol create a disulfiram like reaction

-thromycin suffix

Macrolides

Macrolides most common side effect

Epigastric pain

-cycline suffix

Tetracycline

Tetracyclines attach to what subunit of ribosome

30s, reversibly

Oral adverse effect of Tetracycline

Permanent teeth and bone staining

What can inhibit tetracycline?

Chelation / Dairy

Aminoglycosides bind how and where?

Irreversibly to 30s

3 Types of Aminoglycosides

Gentamicin, Tobramycin, Amikacin

-floxin suffix

Fluoroquinolones

“First antibiotics”

Sulfonamides (Sulfa drugs)

Chloramphenicol Mechanism of action

inhibit peptide bond on 50s subunit

Vancomycin Mechanism of action

Inhibit cell wall synthesis

Two Topical antibiotics

Neosporin and Mupirocin (Bactroban)