29 Antibiotic Medications

What are three criteria that bacteria can be classified on?

1. Aerobic vs anaerobic

2. Shaped (rod, spheres, or spirals)

3. Cell wall components (gram negative or gram positive)

What are the two types of cell walls bacteria can have?

Gram-positive and gram-negative

What makes a bacterium gram-positive?

Possesses a thick cell wall with many layers of peptidoglycan

What makes a bacteria gram negative?

Posses a relatively thin cell wall with few layer of peptidoglycan, surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins.

What type of cell wall is most common for bacteria?

Gram-negative

What is peptidoglycan?

Polysaccharide chains

What are bacterial cell walls made of?

Peptidoglycan, polysaccharide chains.

What is the polymerase responsible for creating GlcNAc and MurNAc strands in peptidoglycan?

Glycosyltransferase (GT)

What id the general name for the strands in peptidoglycan?

Glycan

What two types of glycan strands alternate in peptidoglycan?

N-acetylglucosamine (GLcNAc) and N-acetylmuramic acid (MurNAc)

What is the purpose of the cell membrane in bacterium?

Contribute to the overall structure and shape of bacterium.

What enzyme is responsible for cross linking the glycan strands in peptidoglycan?

Transpeptidase (TP)

What is normal flora?

Microbial species covering humans that do not causes trouble unless the immune systems are weakened or gain access to normally sterile part of the body.

Define Pathogens

Bacteria that do not require the host to be immunocompromised or injured. They enter the host’s cellular and biochemical barriers for survival and multipication.

What are four types of diseases caused by pathogenic bacteria?

Food Borne illnesses, STDs, skin infections, and highly infectious diseases.

What is the strict definition of antibiotics?

Compounds produced and release by microorganisms that inhibit the growth of or kill other microorganisms.

What has the definition of antibiotics been expanded to include?

Synthetically of semi-synthetically produces antimicrobial agents.

What terms can be used to describe antibiotic efficacy and potency?

Spectrum of activity, bacterial sensitivity, therapeutic index, and ability to penetrate.

How does ‘spectrum of activity’ describe antibiotic efficacy and potency?

Can be narrow or broad spectrum, describes the number of different bacterial species against which they are useful.

How does ‘bacterial sensitivity’ describe antibiotic efficacy and potency?

The ability of the bacterial strain to replicate after antibiotic exposure.

What is bactericidal activity?

Leads to the permanent loss of bacterial replicative ability.

What is bacteriostatic activity?

Leads to temporary loss of bacterial growth and replication that returns following the removal of antibiotics.

How does ‘therapeutic index’ describe antibiotic efficacy and potency?

Ration of the minimum concentration to produce and adverse effect to minimum concentration for desired effect. (TD50/ED50)

How does ‘ability to penetrate’ describe antibiotic efficacy and potency?

Ability of the antibiotic to be delivered to the site of infection (most difficult challenge of antibiotic distribution kinetics)

What are the classes of antibiotics?

• Cell wall inhibitors

• Folic Acid

• DNA synthesis inhibitors

• Protein synthesis inhibitors

What are 2 cell wall inhibitors?

Vancomycin, cephalosporins and penicillin.

What is an alternate name for penicillins and cephalosporins?

Beta lactams

What is the mechanism of beta lactams (penicillins and cephalosporins)?

They inhibit DD-transpeptidase, interrupting cell wall synthesis.

Are beta lactams bactericidal or bacteriostatic?

Bactericidal

What is an alternate name for DD transpeptidase?

Penicillin binding protein.

What group of bacteria are beta lactams most effective against?

Gram positive

What kind of beta lactam has increased activity against gram negative bacteria?

Cephalosporins.

What is the name of a cell wall inhibitor that is not a beta lactam?

Vancomycin.

How does vancomycin work?

Inhibits peptidoglycan cross linking.

What antibiotic is produced by Amycolatopsis orientalist, an actinobacteria species?

Vancomycin

What is folic acid used for in bacteria?

Synthesis of nucleic acids that make up their DNA.

What is para-aminobenzoic acid (PABA)?

Nutrient obtained from the environment, the precursor for folate in bacteria.

What class of drug are sulfonamides and trimethoprim?

Folic acid inhibitors.

What are two examples of folic acid inhibitors?

Sulfonamides and trimethoprim.

Are sulfonamides and trimethoprim bacteriostatic or bactericidal?

Bacteriostatic.

What is the mechanism of sulfonamides and trimethoprim?

Resemble PABA and dihydrofolic acid (respectively). They interfere with PABA metabolic pathways. They are usually used together.

What is the bacterial 70s ribosomal complex?

Where bacteria make protein from mRNA.

What is transpeptidation? What is responsible for it?

Amino acid transfer to the growing amino acid chain, tRNA.

What is the mechanism of chloramphenicol and macrolides?

They bind to the 50s subunit and block transpeptidation.

What is the mechanism of tetracyclines?

Bind to the 30s subunit and prevent the binding of incoming tRNA.

What are examples of protein synthesis inhibitors?

Chloaramphenicol, Macrolides, tetracyclines, and aminoglycosides.

What is the mechanism of aminoglycosides?

Bind to the 30s ribosomal subunit, blocking initiation complex, cause misreading of the mRNA, and inhibit translocation.

What makes antibiotics selective to protein synthesis in bacteria?

Humans and microorganisms have differences in their enzymes used. (E.g. mammalian cells do not synthesize folic acid from PABA).

What is the main side effect from antibiotics?

Gastrointestinal distress.

How does antibiotic therapy cause GI distress?

Causes the loss of normal intestinal flora.

What can be used to treat GI distress causes from antibiotic therapy?

Probiotic products, including active culture yogurt.

What is a secondary side effect to antibiotic therapy?

Adverse skin reactions / photosensitivity.

What are rare conditions from adverse skin reaction as a result of antibiotic therapy?

Steven’s-Johnson syndrome and toxic epidermal necrolysis. (Skin detaches from underlying tissue).

What are 4 ways that antibiotic resistance in formed?

1. Drug inactivation or modification

2. Alteration of binding site

3. Alteration of metabolic pathways

4. Reduced drug accumulation (liver and kidney).