Lecture 13: Chemotherapeutic Agents and Antibiotics

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chemotherapeutic agents: A chemical that has been sythesized by chemists in a lab or produced by a modification of a preexisting chemical that kills microorganisms.
antibiotics: a product of the metabolism of a microorganism
What is the objective of a selectively toxic drug?: to kill or inhibit a pathogen while damaging the host as little as possible
What three things does the degree of selective toxicity depend on?: - therapeutic dose
- toxic dose
- therapeutic index
Therapeutic dose: drug level required for clinical treatment of a particular infection

need enough of the drug to kill a pathogen so it can't establish disease
toxic dose: drug level when undesirable effects are produced

-make extremely sick
Therapeutic index: toxic dose/ therapeutic dose

higher therapeutic index, better chemotherapeutic agent
higher therapeutic index, _____ chemotherapeutic agent: better
____ drugs are narrow-spectrum, while ___ are broad-spectrum: most- narrow-spectrum
some- broad-spectrum
Most drugs are narrow-spectrum. They treat ____: only one type of microbe
ISONIAZID is good for tuberculosis. It won't work for something else like a sinus infection. Is it narrow or broad spectrum?: narrow
_____ is a narrow spectrum drug that is good for tuberculosis.: Isoniazid
Some drugs are broad-spectrum. Name three different broad-spectrum drugs.: Neomycin
Zeocin
Sulfonamides
Nemomycin is effective against what bacteria?: gram + and -
Zeocin is a broad-spectrum drug that is _____ AND ____: anti-bacterial and anti-fungal
Sulfonamides is a broad-spectrum drug that is _____, _____, and _____: anti-bacterial
anti-fungal
anti-protozoal
Bactericidal: kills target pathogen
Bacteriostatic: reversibly inhibits growth of pathogen
What is the difference between bactericidal and bacteriostatic?: bactericidal kills. bacteriostatic inhibits.
Antibiotics can be of what three types?: Natural
Synthetic
Semi-synthetic
Natural antibiotics are _____: produced by some living organism
Streptomyces is a living organism that makes what three natural antibiotics?: Streptomycin
chlortetracycline
erythromycin
Streptomycin, chlortetracycline, and erythromycin are natural antibiotics made by what living organism?: streptomyces

*Streptomyces is a bacterium
What living organism makes the natural antibiotic, penicillin?: penicillium

*penicillium is a fungus
*penicillin inhibits bacterial growth
Synthetic antibiotics are what?: manufactured from non-natural products. They are chemotherapeutic agents.
Give two examples of synthetic antibiotics.: sulfonamides
trimethoprim
Semi-synthetic antibiotics are what?: chemical modification of natural antibiotics
Give an example of semi-synthetic antibiotics: penicillin derivatives: ampicillin, carbenicillin, methicillin
Name three penicillin derivatives: ampicillin
carbenicillin
methicillin

* a lot of ppl are allergic to penicillin, so make penicillin derivatives in the lab
What are the 5 mechanisms of antimicrobial action?: - protein synthesis
- nucleic acid
- cell wall
- cell membrane
- metabolic reactions
There are 5 things you can target (protein synthesis, nucleic acid, cell wall, cell membrane, metabolic reactions), that kills microbes, but not ____: but not necessarily the host
What does polymyxin B disrupt?: Cell membrane

*cell membrane is the site of where to attack a microbacterium
Is polymyxin B natural, synthetic, or semi-synthetic?: natural
Polymyxin B is a natural antibiotic that comes from ____: Bacillus
What is polymyxin B effective against?: Gram - bacteria (P. aeruginosa)
Polymyxin B is effective against Gram- bacteria. Give an example: P. aeruginosa
What does polymyxin B do?: Binds cell membrane components, alters membrane permeability (causing cell leakage, death)
Polymyxin B can be found in ______ and _____: bacitracin (Gram +) and neomycin (broad spectrum)
Polymyxin B is only for topical use. If it is ingested, Polymyxin B can cause what?: numbness in the extremities, kidney damage, respiratory arrest
Sulfonamides are natural, synthetic, or semi-synthetic?: synthetic
Give one type of sulfonamide: Sulfanilimide
Sulfanilimide is a structural analog of ____: p-aminobenzoic acid (aka PABA)

(-SO2NH2 vs. COOH)
Sulfonamides inhibits _____ production by competing with p-aminobenzoic acid for active site of dihydropterate synthase, an enzyme: folic acid
Sulfonamides inhibits folic acid production by competing with _____ for active site of dihydropterate synthase, an enzyme: p-aminobenzoic acid
Sulfonamides inhibits folic acid production by competing with --aminobenzoic acid for active site of _____, an enzyme: dihydropterate synthase
Folic acid is required for ____: nucleic acid production
bacteria make their own ____, but not humans: folic acid
Sulfonamides have a high ____, but about 5% of ppl are allergic: therapeutic index
*toxic dose/ therapeutic dose
higher therapeutic index, better chemotherapeutic agent
Give two examples of sulfonamides: sulfamethoxazole
sulfisoxazole
What two antibiotics inhibits DNA Synthesis?: Quinolones
Fluoroquinolones
Give an example of QUINOLONES, which disrupts prokaryotic DNA gyrase (inhibits DNA Synthesis): Nalidixic acid
Nalidixic acid selectively inhibits _____, an enzyme required for DNA replication: DNA gyrase
What is Nalidixic acid effective against?: only effective against certain types of urinary infections.

*most likely narrow-spectrum
Who is Nalidixic acid bad for? whY?: Bad for kids & pregnant women because it affects development of cartilage
Give two types of fluoroquinolones, which inhibits DNA Synthesis: Ciprofloxacin
norfloxacin
Fluoroquinolones were developed as improvements over nalidixic acid (an extra F added), because they ____ and ____: penetrate tissue better

more broad-spectrum (can treat urinary infections + anthrax + others)
What is a drug that inhibits RNA synthesis?: Rifampin
Is Rifampin natural, synthetic, or semi-synthetic?: semi-synthetic
Rifampin inhibits DNA-dependent ______ in bacteria: RNA polymerase, an enzyme
What three things is Rifampin used for?: Tuberculosis
Leprosy
Protection against bacterial meningitis
Rifampin turns bodily secretions ____: reddish orange
what four things inhibits cell wall synthesis?: Penicillins
Bacitracin
Cephalosporins
isoniazid
What do all penicillins have?: beta-lactam nucleus
Penicillins inhibit transpeptidation (linking of polymers w/ amino acid chains) and consequently _____: cell wall synthesis (results in osmotic lysis)
Penicillins inhibit _______(linking of polymers w/ amino acid chains) and consequently cell wall synthesis (results in osmotic lysis): transpeptidation
What is a semi-synthetic derivate of Penicillin?: ampicillin
What is good about ampicillin compared to penicillin?: more acid stable
What are two problems with penicillins?: allergic reactions
growing resistance
If you are allergic to penicillin, then you could take _____: Cephalosporins
What does Cephalosporins inhibit?: cell wall synthesis
Give two examples of cephalosporins: cephalexin (Keflex)
cephalothin (Keflin)
Are cephalosporins natural, synthetic, or semi-synthetic?: Natural, from fungus Cephalosporium
Cephalosporins are a natural antibiotic from the fungus _____: Cephalosporium
Cephalosporins are similar to penicillin in waht way?: beta-lactam ring
similar mechanism of action
Cephalosporins have a beta-lactam ring like penicillin, therefore cephalosporins have a similar _____: mechanism of action
Cephalosporins are a useful alternative to penicillin in case of ___ or ___: allergy or resistance
Bacitracin, another cell wall synthesis inhibitor, interferes with ____, a carrier that transports peptidoglycan subunits to the cell wall: bactoprenol
Give four antibiotics that inhibit Protein Synthesis.: Tetracyclines
Aminoglycosides
Macrolides
Chloramphenicol
Tetracyclines are narrow or braod-spectrum?: broad-spectrum (affects Gram - and +)
What makes up tetracyclines?: four benzene rings
Some tetracyclines are natural and are produced from ___: Streptomyces
Some tetracyclines are natural and produced from Streptomyces. Give two examples.: Chlortetracycline
Oxytetracycline
Some tetracyclines are semi-synthetic. Give four examples.: Tetracyline
Doxycycline
Methacycline
Minocycline
Tetracyclines all inhbibit protein synthesis by binding _______: 30S ribosomal unit
All inhibit protein synthesis by binding 30S ribosomal unit- inhibits binding of _____ to ____: tRNA to ribosome
Who are tetracyclines bad for? why?: Bad for kids and pregnant women- problems with bone formation (yellow teeth)
Tetracyclines is the drug of choice for _____ and _____ diseases: rickettsial and chlamydial diseases
Aminoglycosides inhibits protien synthesis. They are amino groups bound to ____: glycosides (carbohydrates)
What are glycosides?: carbohydrates
What three aminoglycosides comes from Streptomyces?: Streptomycin
Kanamycin
Neomycin
What aminoglycoside comes from Micromonospora purpurea?: Gentamicin
Aminoglycosides prevent reading of ____ by irreversibly binding to ribosome: mRNA
Aminoglycosides prevent reading of mRNA by _____: irreversibly binding to ribosome
Why are aminoglycosides toxic?: Deafness, renal damage, loss of balance
What are macrolides composed of?: 12-22 carbon lactone ring
Are macrolides broad-spectrum or narrow?: broad-spectrum
(Gram +/-, mycoplasma)
Give four examples of macrolides: erythromycin
clindamycin
azithromycin
zithromax
Macrolides inhibit ____: peptide chain elongation
(protein synthesis)
Legionnaire's Disease is transmitted by?: air

air conditioners
humidifiers
the spray of jacuzzi tubs
What are Macrolides used to treat?: Legionnaire's Disease
Chloramphenicol binds ____ and blocks ______ to inhibit protein synthesis: ribosome
peptide bond formation
Is Chloramphenicol natural, synthetic, or semi-synthetic?: natural, from Streptomyces
Where is Chloramphenicol produced from?: Streptomyces
Is Chloramphenicol narrow or broad-spectrum?: broad-spectrum (bacteria, small bacteria, fungi)
Chloramphenicol has a low ____: used only in life-threatening situations: therapeutic index
Chloramphenicol can cause _____ by preventing hemoglobin from being incorporated into RBC (red blood cell): aplastic anemia
Besides aplastic anemia, what else can chloramphenicol cause?: gray syndrome
Gray syndrome is a toxic reaction to chloramphenicol. It is the breakdown of the ___: cardiovascular system
What are the two bad side effects of chloramphenicol?: Aplastic anemia
Gray syndrome
What are the 6 things that affect bacteria?: cell wall
cell membrane
metabolism (folic acid)
DNA synthesis
RNA synthesis
protein synthesis
What are the four mechanisms of resistance?: Modification of target
Prevent entrance of drug
prump drug out of cell
chemical modification
Modification of target. Resistance to ______ develops when bacteria alter structure of enzymes used to synthesize folic acid: sulfonamides
Resistance to _____ develops when bacteria alter structure of ribosomes: streptomycin
Prevent entrance of drug. Mycobacterium has _____ in cell wall: mycolic acid
Mycobacterium has mycolic acid in cell wall. Mycolic acid is _____ to most drugs: impermeable
Pump drug out of cell. Enzymes such as plasma membrane _____ pumps drugs out of cell.: translocase
Pump drug out of cell. Some microbes have ___: multi-drug resistance pumps
Inactivation through Chemical Modification. Penicillinase (beta-lactamase) can effect ______- inactivating antibiotic: hydrolysis of beta-lactam ring
_________ (beta-lactamse) can effect hydrolysis of beta-lactam ring- inactivating antibiotic: Penicillinase
Inactivation through Chemical Modification. Penicillinase (Beta-lactamase) can effect hydrolysis of beta-lactam ring- inactiving antibiotic. This type of resistance can be encoded by ____: plasmids.
transferred by conjugation and transformation
Give two reasons as to why microbial drug resistance is increasing: indiscriminate use of chemotherapeutics

transmission of R factors among microbes
R factors transferred between _____ through conjugation: unrelated strains
What is indiscriminate use? (3 pts): Prescription of antibiotics for viral infections

Low-level use of antibiotics for prevention of infection

inclusion of antibiotics in animal feed
By the process of natural selection, microorganisms that are resistant to a particular drug gradually become ____: predominant in a population
What does PPNG stand for?: penicillinase-producing Neisseria gonorrhoeae

*No PPNG strains before 1976

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