Chapter 14 Study Guide Flashcards
Selectively finding and destroying pathogens without damaging the host
Selective toxicity
The goal is to have antimicrobial agent attack unique features of the pathogen leaving the hosts cells unaffected
Selective toxicity
Why is it generally more difficult to develop anti microbials for eukaryotic and viral infections
Similarity to host cells
Intracellular nature of viruses
Fewer unique targets
High mutation rates
What was the first anti microbial to be developed
Penicillin
Is better called anti microbial because it targets a wide range of microbes, including bacteria.
Penicillin
What is the difference between a synthetic and a semi synthetic drug ?
Synthetic is made in a lab or not found in nature
Semi synthetic is chemically modified derivative of a natural antibiotic
The first true antibiotic discovered was _______. It was discovered by ______.
Penicillin
Alexander Fleming
Cause reverse inhibition of growth, with bacterial growth restarting after elimination of the drug.
Bacteriostatic
Drugs kill their target bacteria
Bactericidal
A ______ targets only specific subsets of bacterial pathogens.
If the pathogen causing an infection has been identified, it is best to use ________.
Narrow spectrum antimicrobial
A __________ targets a wide variety of bacterial pathogens, including both gram positive and gram negative.
Broad spectrum
The risk associated with using broad spectrum antimicrobials that they will also target a broad spectrum of the normal microbiota, increasing the risk of a _________, a secondary infection in a patient having a preexisting infection.
Superinfection
A _______ develops when the antibacterial intended for preexisting infection kills the protective microbiota, allowing another pathogen resistant to the antibacterial to proliferate and cause a secondary infection.
Superinfection
What are the 5 main mechanisms of actions of antibiotics
Inhibit cell wall synthesis
Inhibit protein synthesis
Disruption of cell membrane
Inhibit nucleic acid synthesis
Inhibit metabolic pathways
Which of the 5 mechanisms of actions does penicillin use ?
Inhibit cell wall synthesis
Have a broader spectrum of effectiveness compared to penicillin. They can target a wider range of bacteria, including some gram negative bacteria.
Ampicillin and amoxicillin
Is a semisynthetic penicillin that was developed to address the spread of enzymes that were inactivating the other penicillins
Methicillin
Why is penicillin called a B-lactam antibiotic ?
It contains a B lactam ring that interferes with enzymes that bacteria use to build their cell walls
Examples of B lactam antibiotics
Penicillins
Cephalosporins
Monobactams
Carbapenems
A _______ enzyme breaks down the B lactam ring in B lactam antibiotics, rendering them ineffective against bacteria that produce this enzyme
B lactamase
Tetracyclines and erythromycin kill microbes by
Inhibiting protein synthesis
These drugs target bacterial ribosomes that have 70s ribosomes
Tetracycline and erythromycin
Fluoroquinolones like ciproflaxin, use the mechanism of ________?
Inhibition of nucleic acids
Inhibit folic acid synthesis
Sulfonamides
Is effective against a wide range of bacteria, including gram positive organisms found on the skin, such as staphylococcus and streptococcus
Bacitracin
Is effective against a wide range of bacteria, including gram positive organisms found on the skin, such as staphylococcus and streptococcus
Bacitracin
Why is targeting ergosterol in fungi effective for these kinds of infections ?
Ergosterol is similar to cholesterol, it maintains cell membrane integrity and function
Do human cells have ergosterol ?
No, this makes ergosterol a unique target for anti fungal drugs allowing selective toxicity
Should only be used for life threatening fungal infections because it can also bind to cholesterol, potentially causing kidney damage
Amphotericin B
What are some of the primary targets for anti viral medications ?
Block the receptor ps on the host cell that bind to the virus
Block fusion of the virus and cell
Specifically target influenza viruses by blocking the activity of influenza virus neuraminidase, preventing the release of the virus from infected cells.
Tamiflu
Relentza
Rapivab
Which pathogen are antiretroviral drugs used for ?
HIV
Also interferes with anaerobic bacteria
Treats trichomonas, giardiasis, and amebic dysentery
Metronidazole
Is when bacteria evolve to survive exposure to antibiotics that would normally kill them or stop their growth
Antibiotic resistance
What are the 4 most common mechanisms of antibiotic resistance
Blocking entry
Inactivation by enzymes
Alteration of target molecule
Efflux of antibiotic
Three major ways to test for susceptibility to antimicrobials
Disk diffusion method
Broth dilution test
E-test
The ______ establishes the MIC, determining the lowest concentration of an antimicrobial that inhibits visible bacterial growth
Broth dilution test
Bacteria that are resistant to large number of antibiotics
Superbugs
Are colloquially known as “superbugs” and carry one or more resistance mechanisms, making them resistant to multiple antimicrobials
MDR multi drug resistant microbes
Why is there a concern ? Resistant to many common antibiotics, limiting treatment options
MRSA
Resistant to vancomycin, a last resort antibiotics
VRE and VRSA
Resistant to the most potent TB drugs, leading to longer, more complex treatments with a higher risk of failure.
MDR-TB and XDR-TB
What are some potential safety issues associated with antimicrobial drugs ?
Allergy
Therapeutic index
Reactions of antibiotics with other drugs
Damage to organs
Risk to fetus
The effect of two drugs together is greater than the effect of either alone
Synergism
The effect of two drugs together is less than the effect of either alone
Antagonism
The lowest concentration of drug that inhibits visible bacterial growth
MIC minimal inhibitory concentration
The broth dilution test and the E test can determine the
MIC minimal inhibitory concentration
Reports that record susceptibility of organisms encountered clinically
Antibiograms
A substance produced by a microbe that, in small amounts, inhibits another microbe.
Antibiotic
Synthetic substances that interfere with the growth of microbes
Antimicrobial
The _______ antibacterials block the cross linking of pepetide chains during the biosynthesis of new peptidoglycan in the bacterial cell wall
B lactam drug
Penicillins, cephalosporins, monobactams, and carbapenems all contain a B lactam ring, the site of attack by inactivating _________
B lactamase enzymes
The use of chemicals to treat a disease
Chemotherapy
Are a class of antibiotics used to treat various bacterial infections. They work by inhibiting bacterial DNA synthesis, effectively killing the bacteria.
Ex. Ciproflaxin and Levoflaxin
Fluoroquinolone
Produced by viral infected cells to inhibit further spread of infection
Interferons
Prevent the synthesis of peptidoglycan
Penicillins
A scientist discovers that a soil bacterium he has
been studying produces an antimicrobial that
kills gram-negative bacteria. She isolates and
purifies the antimicrobial compound, then
chemically converts a chemical side chain to a
hydroxyl group. When she tests the antimicrobial
properties of this new version, she finds that this
antimicrobial drug can now also kill gram
positive bacteria. The new antimicrobial drug
with broad-spectrum activity is considered to be
which of the following?
semisynthetic
Which of the following antimicrobial drugs is
synthetic?
sulfanilamide
Which of the following combinations would most
likely contribute to the development of a
superinfection?
Long-term use of broad-spectrum antimicrobials
Which of the following routes of administration
would be appropriate and convenient for home
administration of an antimicrobial to treat a
systemic infection?
oral
Which clinical situation would be appropriate for
treatment with a narrow-spectrum antimicrobial
drug?
Treatment of strep throat caused by culture-identified Streptococcus pyogenes
Which of the following terms refers to the ability
of an antimicrobial drug to harm the target
microbe without harming the host?
selective toxicity
Which of the following is not a type of β-lactam
antimicrobial?
Glycopeptides
Which of the following does not bind to the 50S
ribosomal subunit?
Tetracyclines
Which of the following is not an appropriate
target for antifungal drugs?
cholesterol
Which of the following drug classes specifically
inhibits neuronal transmission in helminths?
avermectins
In the Kirby-Bauer disk diffusion test, the
_______ of the zone of inhibition is measured
and used for interpretation.
diameter
Which of the following techniques cannot be used to determine the minimum inhibitory
concentration of an antimicrobial drug against a
particular microbe?
kirby bauer disk
The utility of an antibiogram is that it shows
antimicrobial susceptibility trends
In a localized population.
An ______ is used to show antimicrobial susceptibility trends in a specific, localized population, such as a hospital or community, helping guide empirical therapy and monitor resistance patterns within that area.
antibiogram
Which of the following has yielded compounds
with the most antimicrobial activity?
soil
Narrow-spectrum antimicrobials are commonly
used for prophylaxis following surgery.
false
β-lactamases can degrade vancomycin.
false
Echinocandins, known as “penicillin for fungi,”
target β(1→3) glucan in fungal cell walls.
true
The rate of discovery of antimicrobial drugs has
decreased significantly in recent decades.
true
If drug A produces a larger zone of inhibition
than drug B on the Kirby-Bauer disk diffusion
test, drug A should always be prescribed.
false
The bacterium known for causing
pseudomembranous colitis, a potentially deadly
superinfection, is ________.
c. diff
Selective toxicity antimicrobials are easier to
develop against bacteria because they are
________ cells, whereas human cells are
eukaryotic.
prokaryotic
Antiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by
preventing viral escape from host cells are called
neuraminidase inhibitors.
Staphylococcus aureus, including MRSA strains,
may commonly be carried as a normal member
of the ________ microbiota in some people.
nasal microbiota
The method that can determine the MICs of
multiple antimicrobial drugs against a microbial
strain using a single agar plate is called the
________.
E test
Where do antimicrobials come from naturally?
Why?
bacteria and fungi;
How does the biology of HIV necessitate the
need to treat HIV infections with multiple drugs?
high mutation rate
What bacterial structural target would make an
antibacterial drug selective for gram-negative
bacteria? Provide one example of an
antimicrobial compound that targets this
structure.
The outer membrane of gram-negative bacteria is a key structural target for selective antibacterial drugs. An example of an antimicrobial compound that targets this structure is polymyxin B.
inhibiting cell wall synthesis _____ prevent the synthesis of peptidoglycan
penicillin
inhibiting protein synthesis– Target bacterial 70S ribosomes
Chloramphenicol, erythromycin, streptomycin,
tetracyclines
