Chapter 10 Flashcards
Who discovered the original penicillin in 1928? (a shot)
Alexander Flemming
A drug must be able to?
- easy to administer
- able to reach the infectious agents anywhere in the body
- selectively toxic
- remain in the body as long as needed, and can be safely and easily broken down and excreted
- very few drugs meet all these
absolutely toxic to the infectious agent and nontoxic to the host this is?
selectively toxic
Drugs from bacteria?
streptomyces and bacillus
Drugs from mold?
Penicillium and cephalopsporium
Before starting treatment what are the three factor you must know?
- nature of the microorganism
- degree of the microorganisms susceptibility (sensitivity) to various drugs.
- overall medical condition of the patient.
What test for drug susceptibility measures the zone of inhibition surrounding the discs is measured and compared with a standard for each drug?
Kirby-Bauer technique
What test for drug susceptibility is this?
-Antimicrobial is diluted
-Each tube is inoculated with a small uniform sample of pure culture
-Minimum inhibitory concentration
The test can be expanded to determine a MBC (Minimum bactericidal concentration
Tube dilution tests
What is the smallest concentration (highest dilution) of drug that visibly inhibits growth?
Minimum inhibitory concentration
What are the two tests that test drug susceptibility?
- Kirby-Bauer technique
- Tube dilution tests
What is the ratio of the dose of the drug that is toxic to humans as compared to its minimum effective (therapeutic) dose
Therapeutic index
1.1 is?
a risky choice for drug reactions.
Before prescribing an antibiotic a doctor should ask?
- Preexisting conditions
- History of allergy
- Underlying liver or kidney disease
- Infants, the elderly, and pregnant
Drug testing summary includes?
- Lab tests
- Animal tests
- Human Clinical Trials
Which phase is done in healthy young people (usually males) to test for toxicity
Phase I Clinical trial of Human Clinical Trials
Which phase is done in persons with the infection or disorder to see if the drug is effective
Phase II clinical trials of Human Clinical Trials
Which phase continues after phase II but compares the drug to any current treatments on the market
Phase III clinical trials of Human Clinical Trials
Which phase occurs after market studies
Phase IV of Human Clinical Trials
What are these?
- Inhibition of cell wall synthesis
- Inhibition of nucleic acid structure and function
- Inhibition of protein synthesis
- Interference with cell membrane structure and function
- Inhibition of a metabolic process
Modes of actions for Antimicrobial drugs
What targets peptidoglycan
Inhibition of cell wall synthesis
DNA or RNA structure or synthesis is?
DNA or RNA structure or synthesis is?
What targets the prokaryotic ribosome
Inhibition of protein synthesis
What targets the plasma membrane
Interference with cell membrane structure and function
What targets a metabolic process in the microbe that is different
Inhibition of a metabolic process
What is effective against more than one group of bacteria
- Advantage is that you don’t have to know the cause of the infection first
- Disadvantage is that you will kill normal flora and cause a superinfection
Broad-spectrum drugs
What targets a specific group?
- Advantage is that you will not kill normal flora (at least not as much)
- Disadvantage is that you must be reasonably sure of the cause of the infection
Narrow-spectrum drugs
Which are the microbes that were once small in number overgrow when normal resident biota are destroyed by broad-spectrum antimicrobials
Superinfection
A later version could be taken as a pill but had to be taken every 4 hours
Penicillin
Semisynthetic penicillins are?
altered, they work better.
What do biofilms do for bacteria?
protect them
What are the five Classes of Antimicrobials?
Antibacterial drugs Antifungal drugs Antiprotozoal drugs Antihelminthic drugs Antiviral drugs
Antibacterials that Target the cell wall are?
Penicillins Clavulanic acid Cephalosporins Carbepenems Bacitracin Vancomycin Isoniazid Ethambutol
What am i?
- Many semisynthetics available.
- Only problem in allergic reactions.
- Resistant microbes produce beta lactamase that break the central ring of the penicillin molecule (the beta lactam ring)
Penicillin
Who am i?
- Inhibits beta lactamase enzymes
- Added to penicillins to reduce resistance
- Example: Augmentin (clavulanic acid + amoxicillin)
Clavulanic acid
Who am i?
- Many generations available
- Good for people allergic to penicillin
- Can be affected by beta lactamase producing microbes
Cephalosporins
Who am i?
- Good for people allergic to penicillin
- Broad Spectrum
- Reserved for more serious infections
- Resistant to beta lactamase enzymes
Carbepenems
What is used topically against staph and strep. Found in triple antibiotic ointment?
Bacitracin
What is used for multidrug resistant staph or strep infections?
Vancomycin
What inhibits the synthesis of mycolic acid?
Also used in combination therapy to treat tuberculosis and leprosy.
Isoniazid
What prevents the encorporation of mycolic acid in the cell wall.
Also used in combination with isoniazid.
Ethambutol
Antibacterials that Target 70S ribosomes (protein synthesis) are?
- Streptomycin
- Neomycin
- Tetracycline
- Erythromycin
- Clindamycin
Who am i?
- first drug to treat Gram negative infection and tuberculosis
- Broad spectrum
- Can cause nephrotoxicity and ototoxicity
Streptomycin (1943)
Who am i?
- treats Gram negative infection
- Is nephrotoxic so is usually used topically (part of the triple antibiotic ointment
Neomycin
Who am i?
- Very broad spectrum
- Can stain growing teeth brown
- Causes superinfections
Tetracycline
Who am i?
- Family of antibiotics (includes the “Z pack”)
- Good for patients allergic to penicillin
- Used of respiratory, ear and skin infections
Erythromycin
Who am i?
- Used to treat drug resistant staph and stomach and intestinal infections that do not respond to other medications
- Good for anaerobic infections
Clindamycin
Antibacterials that microbial metabolism are?
Sulfonamides
Trimethoprim
Who am i?
-Inhibit the synthesis of folic acid
Sulfonamides
What is a sulfonamide and is used for UTI’s?
Trimethoprim
Antibacterials that target DNA or RNA are?
Fluoroquinolones
Rifamycin
- Inhibit bacterial topoisomerases or helicases (inhibit DNA synthesis)
- Used for serious infections like anthrax, kidney infections, pneumonia, etc.
Fluoroquinolones
- Inhibits RNA synthesis
- Used for tuberculosis (in combination with isoniazid and ethambutol)
- Also used for meningitis
Rifammycin
Folic acid is need to synthesize ___ and ___ nucleotides
DNA and RNA
We don’t make our own _______, we get it in our diet
folic acid
Antibacterials that target the Plasma Membrane
Polymyxin B
- Interacts with phospholipids and distorts the plasma membrane, making it leaky
- Most effective against Gram negative bacteria
- Usually used topically (part of the triple antibiotic ointment)
- Can be used against Pseudomonas
Polymyxin B
