Clinical Medicine with Complete
Solutions
What type of antibiotic is good for bloodstream infections - bacteriostatic or
bacteriocidal? - correct answer-Bacteriocidal
T/F? Penicillin is a broad spectrum antibiotic? - correct answer-False, it is narrow
spectrum
What broad classes of bacteria does penicillin cover? - correct answer-- Gram +
- Anaerobes
What are the 2 classes of cell wall synthesis inhibitors? - correct answer-1. Beta-
Lactams: these bind to and blocks transpeptidase (a penicillin binding protein) and
prevent formation of the cross-links in peptidoglycan
2. Glycopeptides: bind to the terminal amino acid of tetrapeptide and blocks
transpeptidase from acting
What does penicillin-binding protein do? - correct answer-It forms the 1,4 cross links
between NAMS and UMP on the exterior of the bacterial cell for completion of
peptidoglycan synthesis
- inhibited by penicillin
What does transpeptidase (a penicillin binding protein) do? - correct answer-- Forms
peptide cross links between glycan chains to make peptidoglycan layers
T/F? Beta-lactams and glycopeptides are bacteriostatic? - correct answer-False, they
are all bactericidal
Name the 4 classes of beta-lactams. - correct answer-1. Penicillin
2. Cephalosporins
3. Carbapenems
4. Monobactams
Describe penicillins. - correct answer-- Original was only used in gram + bacteria
(modifications now used against both gram + and gram -)
- Penicillins are sensitive to beta-lactamase that is secreted by the bacteria and cause
it to be ineffective
Name the modifications of penicillins. - correct answer-1. Ampicillin
2. Amoxicillin
,3. Methicillin
What are cephalosporins? - correct answer-- Structure: Beta-Lactam ring attached to a
6-member ring
- Beta-Lactamase resistant
- Classified according to each generation: each generation corresponds to a
modification that improves absorption and increases spectrum (classes 1-5)
What generations of Cephalosporins are resistant against both gram - and gram +
bacteria? - correct answer-4 and 5
Describe carbapenems. - correct answer-- Newly made in the 1990s
- Broadest spectrum
- Resistant to beta lactamase
- Can only be given thru IV in a hospital
- Useful against gram - bacteria that are resistant to many other drugs
Which beta-lactams are resistant to beta-lactamase? - correct answer-- Methicillin (only
1 derivative of penicillin)
- Cephalosporins
- Carbapenems
- Monobactams
What are the two types of glycopeptide antibiotics available? - correct answer--
Vancomycin
- Teichoplanin
Describe Vancomycin and Teichoplanin. - correct answer-- Bind to the terminal amino
acid, alanine, of the tetrapeptide chain and prevent transpeptidase from making cross-
links between the peptidoglycans
- Lipophilic
- Only used against gram + bacteria
- Administered via IV
- Drug of choice for hospital acquired MRSA
(Pneumonic - In the hospital watch a lot of TV which is positive - so the Teichoplanin
and Vancomycins are given for hospital acquired MRSA and useful against gram + only)
What are the 6 types of protein synthesis inhibitors? - correct answer-1.
Aminoglycosides (A)
2. Tetracyclines (T)
3. Erythromycin (E)
4. Chloramphenicol (C)
5. Clindamycin
6. Oxazolidonones
7. Macrolides
ATECCOM
,Which, if any, of the protein synthesis inhibitor antibiotics are bactericidal? - correct
answer-Aminoglycosides
What antibacterial agents are useful against hospital acquired and regular MRSA
(separately)? - correct answer-- Hospital acquired: Vancomycin and Teichoplanin
- Regular MRSA: Oxazolidones
What are the 4 categories of drugs that inhibit nucleic acid synthesis? - correct answer-
1. Quinolones
2. Folate synthesis
3. Methonidazole
4. Rifampin
Describe the quinolones. - correct answer-- Bacteriocidal
- Inhibit DNA gyrase (a topoisomerase 1)
- Broad spectrum, effective against intracellular microbes (viruses)
- Administered orally
- Well tolerated/mild on host
- The examples Ciprofloxacin and Levoquin have a fluorine derivative added for
improved absorption that can cause tendon rupture and peripheral neuropathy
Describe Rifampin. - correct answer-- Bacteriocidal
- Binds to the beta subunit of RNA polymerase and makes it non functional; so inhibits
transcription and translation
- Use is restricted to treatment of mycobacterium tuberculosis (an opportunistic
infection associated with HIV) or prophylactic for meningities
How do mycobacterium tuberculosis become resistant to Rifampin? - correct answer--
When using, mycobacterium replicates VERY slowly, slower than eukaryotic cells, so
these drugs must be given for long time periods (6 months to a year).
- Over time the virus develops resistance, via changing their RNA polymerase. So
Rifampin is used in combination with another drug
Decribe folate inhibitors. - correct answer-- Bacteriostatic
- Bacteria make folate to make the deoxyribonucleotides for DNA synthesis (humans
get folate from diet, while bacteria make it)
- Folate synthesis pathway is an absolute selective pathway
- Resistance to the sulfonamids became common because it was used so much
Describe sulfonamides. - correct answer-- Earliest folate synthesis inhibitor
- Is a structural analog of paramino benzoic acid (PABA), so it blocks folate synthesis
by binding to the dihydropteroic acid
- Resistance to the sulfonamides (e.g., Sulfamethoxazole) became so common place
that now the drugs have to be given in combination with Trimethoprim which will block
the dihydrofolate reducatase so that tetrahydrofolate is not made
, How are bacteria resistant to sulfonilamides? - correct answer-- By altering their
dihydrofolate reducatses
- By altering their dihydropteroate synthase
Describe the cell membrane disrupter antimicrobials. - correct answer-- Called
Polymixins
- Highly toxic to the brain and kidney by binding to membranes rich in
phosphatidylethanolamine
- Act as a detergent
- Used in 3rd world countries; not used in the US
- Disrupt membrane integrity of bacteria cells and our cells
Describe the mechanism for enzymatic inactivation of beta-lactam antibiotics. - correct
answer-- Penicillin resistance: Penicillin normally binds to transpeptidase and prevents
cross-linking
- Some gram + bacteria make beta-lactamase which cleaves the beta lactam ring
making the penicillin inactive; peptide crosslinks occur and bacteria live
What drug is used to inhibit beta-lactamase? - correct answer-- Clavulanic acid, alone it
has minimal bactericidal activity. Used in combination with other beta lactam antibiotics,
the clavulanic acid acts as a suicide inhibitor.
- It is cleaved by the beta lactamase and then binds to beta lactamase and makes it
inactive, its cleavage allows the beta lactam antibiotic to remain functional
What are a few indications for penicillin use? - correct answer-- Steptococcus pyogenes
cellulitis, dental infections, etc.
What are the symptoms of Strep. Pyogenes cellulitis? - correct answer-Spread of group
A streptococcus pyogenes to the subcutaneous layer of the skin causes a red, painful
rash that may be swollen
T/F? Penicillin inhibits cell wall synthesis? - correct answer-True
Would you give 2 or more beta-lactams at the same time? - correct answer-False
Which Penicillin provides coverage for MRSA? - correct answer-Ceftaroline
T/F? When someone comes into the hospital you would start them on penicillin right
away? - correct answer-False, you don't give penicillin right away because it has too
narrow of a spectrum
Why were semisynthetic penicillins developed? - correct answer-Because penicillins
became inhibited by beta lactamase
Solutions
What type of antibiotic is good for bloodstream infections - bacteriostatic or
bacteriocidal? - correct answer-Bacteriocidal
T/F? Penicillin is a broad spectrum antibiotic? - correct answer-False, it is narrow
spectrum
What broad classes of bacteria does penicillin cover? - correct answer-- Gram +
- Anaerobes
What are the 2 classes of cell wall synthesis inhibitors? - correct answer-1. Beta-
Lactams: these bind to and blocks transpeptidase (a penicillin binding protein) and
prevent formation of the cross-links in peptidoglycan
2. Glycopeptides: bind to the terminal amino acid of tetrapeptide and blocks
transpeptidase from acting
What does penicillin-binding protein do? - correct answer-It forms the 1,4 cross links
between NAMS and UMP on the exterior of the bacterial cell for completion of
peptidoglycan synthesis
- inhibited by penicillin
What does transpeptidase (a penicillin binding protein) do? - correct answer-- Forms
peptide cross links between glycan chains to make peptidoglycan layers
T/F? Beta-lactams and glycopeptides are bacteriostatic? - correct answer-False, they
are all bactericidal
Name the 4 classes of beta-lactams. - correct answer-1. Penicillin
2. Cephalosporins
3. Carbapenems
4. Monobactams
Describe penicillins. - correct answer-- Original was only used in gram + bacteria
(modifications now used against both gram + and gram -)
- Penicillins are sensitive to beta-lactamase that is secreted by the bacteria and cause
it to be ineffective
Name the modifications of penicillins. - correct answer-1. Ampicillin
2. Amoxicillin
,3. Methicillin
What are cephalosporins? - correct answer-- Structure: Beta-Lactam ring attached to a
6-member ring
- Beta-Lactamase resistant
- Classified according to each generation: each generation corresponds to a
modification that improves absorption and increases spectrum (classes 1-5)
What generations of Cephalosporins are resistant against both gram - and gram +
bacteria? - correct answer-4 and 5
Describe carbapenems. - correct answer-- Newly made in the 1990s
- Broadest spectrum
- Resistant to beta lactamase
- Can only be given thru IV in a hospital
- Useful against gram - bacteria that are resistant to many other drugs
Which beta-lactams are resistant to beta-lactamase? - correct answer-- Methicillin (only
1 derivative of penicillin)
- Cephalosporins
- Carbapenems
- Monobactams
What are the two types of glycopeptide antibiotics available? - correct answer--
Vancomycin
- Teichoplanin
Describe Vancomycin and Teichoplanin. - correct answer-- Bind to the terminal amino
acid, alanine, of the tetrapeptide chain and prevent transpeptidase from making cross-
links between the peptidoglycans
- Lipophilic
- Only used against gram + bacteria
- Administered via IV
- Drug of choice for hospital acquired MRSA
(Pneumonic - In the hospital watch a lot of TV which is positive - so the Teichoplanin
and Vancomycins are given for hospital acquired MRSA and useful against gram + only)
What are the 6 types of protein synthesis inhibitors? - correct answer-1.
Aminoglycosides (A)
2. Tetracyclines (T)
3. Erythromycin (E)
4. Chloramphenicol (C)
5. Clindamycin
6. Oxazolidonones
7. Macrolides
ATECCOM
,Which, if any, of the protein synthesis inhibitor antibiotics are bactericidal? - correct
answer-Aminoglycosides
What antibacterial agents are useful against hospital acquired and regular MRSA
(separately)? - correct answer-- Hospital acquired: Vancomycin and Teichoplanin
- Regular MRSA: Oxazolidones
What are the 4 categories of drugs that inhibit nucleic acid synthesis? - correct answer-
1. Quinolones
2. Folate synthesis
3. Methonidazole
4. Rifampin
Describe the quinolones. - correct answer-- Bacteriocidal
- Inhibit DNA gyrase (a topoisomerase 1)
- Broad spectrum, effective against intracellular microbes (viruses)
- Administered orally
- Well tolerated/mild on host
- The examples Ciprofloxacin and Levoquin have a fluorine derivative added for
improved absorption that can cause tendon rupture and peripheral neuropathy
Describe Rifampin. - correct answer-- Bacteriocidal
- Binds to the beta subunit of RNA polymerase and makes it non functional; so inhibits
transcription and translation
- Use is restricted to treatment of mycobacterium tuberculosis (an opportunistic
infection associated with HIV) or prophylactic for meningities
How do mycobacterium tuberculosis become resistant to Rifampin? - correct answer--
When using, mycobacterium replicates VERY slowly, slower than eukaryotic cells, so
these drugs must be given for long time periods (6 months to a year).
- Over time the virus develops resistance, via changing their RNA polymerase. So
Rifampin is used in combination with another drug
Decribe folate inhibitors. - correct answer-- Bacteriostatic
- Bacteria make folate to make the deoxyribonucleotides for DNA synthesis (humans
get folate from diet, while bacteria make it)
- Folate synthesis pathway is an absolute selective pathway
- Resistance to the sulfonamids became common because it was used so much
Describe sulfonamides. - correct answer-- Earliest folate synthesis inhibitor
- Is a structural analog of paramino benzoic acid (PABA), so it blocks folate synthesis
by binding to the dihydropteroic acid
- Resistance to the sulfonamides (e.g., Sulfamethoxazole) became so common place
that now the drugs have to be given in combination with Trimethoprim which will block
the dihydrofolate reducatase so that tetrahydrofolate is not made
, How are bacteria resistant to sulfonilamides? - correct answer-- By altering their
dihydrofolate reducatses
- By altering their dihydropteroate synthase
Describe the cell membrane disrupter antimicrobials. - correct answer-- Called
Polymixins
- Highly toxic to the brain and kidney by binding to membranes rich in
phosphatidylethanolamine
- Act as a detergent
- Used in 3rd world countries; not used in the US
- Disrupt membrane integrity of bacteria cells and our cells
Describe the mechanism for enzymatic inactivation of beta-lactam antibiotics. - correct
answer-- Penicillin resistance: Penicillin normally binds to transpeptidase and prevents
cross-linking
- Some gram + bacteria make beta-lactamase which cleaves the beta lactam ring
making the penicillin inactive; peptide crosslinks occur and bacteria live
What drug is used to inhibit beta-lactamase? - correct answer-- Clavulanic acid, alone it
has minimal bactericidal activity. Used in combination with other beta lactam antibiotics,
the clavulanic acid acts as a suicide inhibitor.
- It is cleaved by the beta lactamase and then binds to beta lactamase and makes it
inactive, its cleavage allows the beta lactam antibiotic to remain functional
What are a few indications for penicillin use? - correct answer-- Steptococcus pyogenes
cellulitis, dental infections, etc.
What are the symptoms of Strep. Pyogenes cellulitis? - correct answer-Spread of group
A streptococcus pyogenes to the subcutaneous layer of the skin causes a red, painful
rash that may be swollen
T/F? Penicillin inhibits cell wall synthesis? - correct answer-True
Would you give 2 or more beta-lactams at the same time? - correct answer-False
Which Penicillin provides coverage for MRSA? - correct answer-Ceftaroline
T/F? When someone comes into the hospital you would start them on penicillin right
away? - correct answer-False, you don't give penicillin right away because it has too
narrow of a spectrum
Why were semisynthetic penicillins developed? - correct answer-Because penicillins
became inhibited by beta lactamase
