What is the use of drugs to treat a disease?

Chemotherapy

What interferes with the growth of microbes within a host?

antimicrobial drugs

What is a substance produced by a microbe that, in small amounts, inhibits another microbe?

antibiotic

What is it called when a drug that kills harmful microbes without damaging the host?

selective toxicity

What is the source of more than half of the antibiotics?

Streptomyces, a filamentous soil bacterium, other from Bacillus and molds (fungi)

According to Table 20.1, which group microorganisms are most antibiotics derived from?

Actinomycetes

Which spectrum have the least side effects?

Narrow spectrum - it only impacts certain types of pathogens (penicillin affects primarily Gram positive)

Antibiotics only work to destroy...

bacteria

Which spectrum antibiotics have a small range of pathogens they are effective against?

Narrow

Which spectrum antibiotics have a broad range of pathogens they are effective against?

Broad (effect Gram negative or Gram positive)

What is the danger of broad spectrum antibiotics?

Normal microbial flora will also be destroyed and can lead to a superinfection (when a surviving organism overgrows like fungus)

What are the criteria for ideal antibiotics?

Selective toxicity

soluble in body fluid in (blood brain barrier)

Resists excretion (stays in the body long enough)

Shelf life

Doesn't lead to resistance

Cost not excessive

Hypoallergenic (natural or synthetic)

What are the actions of antimicrobial drugs?

Inhibition of cell wall synthesis (penicillins)

Inhibition of protein synthesis (erythromycin, tetracycline)

Inhibition of synthesis of essential metabolites *this makes an antimicrobial a "magic bullet" since bacteria has folic acid and we (humans) do not

Inhibition of nucleic acid replication and transcription (quinolones)

If an antimicrobial drug inhibits organelles that are 70s why is it not a "magic bullet" or in other words, why is it not an effective antimicrobial drug for humans?

In order for a drug to be a "magic bullet" it has to kill the pathogen but not hurt the host. Drugs that target organelles with 70s cannot be a magic bullet because mitochondria are also 70s and would be impacted by the drug.

Which drug is an example of an antibacterial antibiotic cell wall inhibitor?

Penicillin

What is the common core of penicillins?

B-lactam ring which is CH-CH-N-C and this prevents cell wall formation

What breaks the b-lactam ring?

Penicillinase

What is natural penicillin?

Natural from mold

Best use for streptococcus spp and most staphylococcus

What is semisynthetic penicillin?

More resistant to penicillinase

Methicillin-resistant - Staphylococcus aureus (MRSA)

The administration of penicillin: Penicillin G requires...

Injection because stomach acid destroys it

The administration of penicillin: Penicillin Y requires...

Either injection or orally

What are cephalosporins?

Narrow spectrum

Inhibits cell wall formation in gram positive pathogens

2nd generation- extended spectrum includes gram negative

3rd generation - includes pseudonomads, injected

4th generation - oral

What are some polypeptide antibiotics?

Bacitracin - topical application (less risk since not injected or consumed); works against gram positive

Vancomycin - glycopeptide, "last line" against antibiotic resistant S. aureus

What is the last line against antibiotic resistant S. aureus?

Vancomycin

Patient must be hospitalized

Drug will affect kidneys

Where is all antibiotic resistance?

In the plasmid

What are antimycobacterium antibiotics?

Isoniazid (INH) - inhibits mycolic acid synthesis

Ethambutol - inhibits incorporation of mycolic acid

Which antibacterial antibiotics inhibit protein synthesis?

chloramphenicol, erythromycin,streptomycin, tetracyclines

What are the side effects of streptomycin?

Can cause auditory nerve damage and possibly kidney damage

What are the side effects of tetracyclines?

Suppression of normal flora and cause superinfections; brownish discoloration of teeth in children; possible kidney damage in pregnant women

What is chloramphenicol?

simple structure, easily manufactured; broad spectrum and penetrates body well, but has some serious side effects. Used only when no suitable alternatives are available

What are macrolides?

Contain macrocyclic lactone ring (i.e. erythromycin - not able to penetrate most Gram negative cell walls, so limited spectrum - often alternative to penicillin)

Which drug is a broad spectrum drug that binds 50S subunit, inhibits peptide bond formation?

Chloramphenicol

Which drug is a broad spectrum drug that changes the shape of 30S subunit?

Aminoglycosides (streptomycin, neomycin, gentamycin)

Which drug is a broad spectrum drug that interferes with tRNA attachment?

Tetracyclines

Which drug affects Gram-positive; binds 50S, prevents translocation?

Erythromycin and macrolides

Which drug affects Gram positives, binds 50S, prevents translocation?

Erythromycin and macrolides

Which drug affects Gram positives, binds 50S subunit, inhibits translation?

Streptogramins and synercid

Which drug affects Gram positives, binds 50S subunit, prevents formation of 70S ribosome?

Oxazolidinones (Linezolid)

Occurs when the effect of two drugs together is greater than the effect of either alone. When combination of drugs provides the same effect at a fraction of the concentration of either alone

Synergism

Occurs when the effect of two drugs together is less than the effect of either alone.

Antagonism

List ways in which antibiotics are misused

Using outdated, weakened antibiotics

Using antibiotics for the common cold and other inappropriate conditions

Use of antibiotics in animal feed

Failure to complete the prescribed regimen

Using someone else's leftover prescription

Can determine MIC and also minimal bactericidal concentration (MBC)

broth dilution

What percentage of Americans get a viral disease per year?

90%

Are very limited in which groups they are effective against and most have been developed in response to HIV (AIDS)

anitviral drugs

synthetic nucleosides which interfere with DNA and RNA synthesis

Nucleosides analogs

Inactivates reverse transcriptase (needed to make DNA from RNA viral genome)

enzyme inhibitors

Any drug ending -zole is which type of drug?

Antifungal drug

Interferes with sterol synthesis

imidazoles and triazoles

interferes with mitosis and thus inhibits fungal reproduction. Useful against infections of fungi in hair and nails

griseofulvin

Produced by Streptomyces, combine with sterols in the fungal plasma membrane and make the membrane excessively permeable which kills the cell

polyenes

Why are fungi harder to attack?

Because fungi are also eukaryotic

What is a broad spectrum drug that binds to 50S subunit, inhibits peptide bond formation

Chloramphenicol

Contain macrocyclic lactone ring (ex. erythromycin) and not able to penetrate most Gram negative cell walls, so limited spectrum - often alternative to penicillin

Macrolides

Which drug has a simple structure, easily manufactured (more cheaply than isolating from Streptomyces). Broad spectrum and penetrates body well, but has some serious side effects. Used only when no suitable alternatives are available

Chloramphenicol

Which bactericidal can cause auditory nerve damage and possibly kidney damage?

Streptomycin

What broad spectrum drug produced by Streptomyces penetrates body tissues well and are effective against intracellular rickettsias and chlamydias

Tetracyclines

Can suppress the normal flora and cause superinfections. Not advised for children due to brownish discoloration of teeth or for pregnant women (possible liver damage)

Tetracyclines

What glycopeptide is the important "last line" against antibiotic resistant S. aureus

Vancomycin

All antibiotic resistance is though the ______

Plasmid - double stranded DNA in the plasma

Which type of penicillin can only be injected because it is destroyed by stomach acid?

Penicillin G

Which type of penicillin can be administered orally or by injection?

Penicillin V

Which are the natural penicillin?

Penicillin G and V

What advantage does semisynthetic penicillin have over natural penicillin?

It is resistant to penicillinase and has an extended spectrum

Which is natural from mold and is the choice for Streptococcus and Staphylococcus spp?

Natural penicillin

Which is more resistant to penicillinase and Methicillin resistant - Staphylococcus aureus (MRSA)

Semisynthetic penicillin

What does the b lactam ring do?

prevents cell wall making

What does penicillinase do?

breaks the ring and makes penicillin inactive

What is the common core of penicillin

b lactam ring

What are the same as b lactinase inhibitors?

carbapenems and monobactam

what are the inhibitors of cell wall synthesis?

Penicillin - penicillinase-resistant penicillins

extended spectrum penicillins

penicillins - b lactamase inhibitors

carbapenems

monobactam