Clinical Medicine
What type of antibiotic is good for bloodstream infections - bacteriostatic or bactericidal? - ANS
-Bactericidal
T/F? Penicillin is a broad spectrum antibiotic? - ANS -False, it is narrow spectrum
What broad classes of bacteria does penicillin cover? - ANS -- Gram +
- Anaerobes
What are the 2 classes of cell wall synthesis inhibitors? - ANS -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? - ANS -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? - ANS -- Forms peptide cross links
between glycan chains to make peptidoglycan layers
T/F? Beta-lactams and glycopeptides are bacteriostatic? - ANS -False, they are all bactericidal
Name the 4 classes of beta-lactams. - ANS -1. Penicillin
2. Cephalosporins
3. Carbapenems
4. Monobactams
Describe penicillins. - ANS -- 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. - ANS -1. Ampicillin
2. Amoxicillin
3. Methicillin
What are cephalosporins? - ANS -- 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? -
ANS -4 and 5
Describe carbapenems. - ANS -- 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? - ANS -- Methicillin (only 1 derivative of
penicillin)
- Cephalosporins
- Carbapenems
- Monobactams
What are the two types of glycopeptide antibiotics available? - ANS -- Vancomycin
- Teichoplanin
Describe Vancomycin and Teichoplanin. - ANS -- 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? - ANS -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? - ANS
-Aminoglycosides
,What antibacterial agents are useful against hospital acquired and regular MRSA (separately)? -
ANS -- Hospital acquired: Vancomycin and Teichoplanin
- Regular MRSA: Oxazolidones
What are the 4 categories of drugs that inhibit nucleic acid synthesis? - ANS -1. Quinolones
2. Folate synthesis
3. Methonidazole
4. Rifampin
Describe the quinolones. - ANS -- 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. - ANS -- 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? - ANS -- 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. - ANS -- 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. - ANS -- 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? - ANS -- By altering their dihydrofolate reducatses
- By altering their dihydropteroate synthase
, Describe the cell membrane disrupter antimicrobials. - ANS -- 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. - ANS -- 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? - ANS -- 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? - ANS -- Steptococcus pyogenes cellulitis, dental
infections, etc.
What are the symptoms of Strep. Pyogenes cellulitis? - ANS -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? - ANS -True
Would you give 2 or more beta-lactams at the same time? - ANS -False
Which Penicillin provides coverage for MRSA? - ANS -Ceftaroline
T/F? When someone comes into the hospital you would start them on penicillin right away? -
ANS -False, you don't give penicillin right away because it has too narrow of a spectrum
Why were semisynthetic penicillins developed? - ANS -Because penicillins became inhibited by
beta lactamase
What does beta lactamase do? - ANS -Enzyme that breaks up the beta lactam ring and makes
penicillin unable to bind to penicillin-binding proteins on bacteria
What was the prototype for semisynthetic penicillins? - ANS -Methicillin
List the extended spectrum penicillins. - ANS -- Aminopenicillins
- Carboxypenicillins
What type of antibiotic is good for bloodstream infections - bacteriostatic or bactericidal? - ANS
-Bactericidal
T/F? Penicillin is a broad spectrum antibiotic? - ANS -False, it is narrow spectrum
What broad classes of bacteria does penicillin cover? - ANS -- Gram +
- Anaerobes
What are the 2 classes of cell wall synthesis inhibitors? - ANS -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? - ANS -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? - ANS -- Forms peptide cross links
between glycan chains to make peptidoglycan layers
T/F? Beta-lactams and glycopeptides are bacteriostatic? - ANS -False, they are all bactericidal
Name the 4 classes of beta-lactams. - ANS -1. Penicillin
2. Cephalosporins
3. Carbapenems
4. Monobactams
Describe penicillins. - ANS -- 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. - ANS -1. Ampicillin
2. Amoxicillin
3. Methicillin
What are cephalosporins? - ANS -- 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? -
ANS -4 and 5
Describe carbapenems. - ANS -- 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? - ANS -- Methicillin (only 1 derivative of
penicillin)
- Cephalosporins
- Carbapenems
- Monobactams
What are the two types of glycopeptide antibiotics available? - ANS -- Vancomycin
- Teichoplanin
Describe Vancomycin and Teichoplanin. - ANS -- 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? - ANS -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? - ANS
-Aminoglycosides
,What antibacterial agents are useful against hospital acquired and regular MRSA (separately)? -
ANS -- Hospital acquired: Vancomycin and Teichoplanin
- Regular MRSA: Oxazolidones
What are the 4 categories of drugs that inhibit nucleic acid synthesis? - ANS -1. Quinolones
2. Folate synthesis
3. Methonidazole
4. Rifampin
Describe the quinolones. - ANS -- 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. - ANS -- 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? - ANS -- 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. - ANS -- 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. - ANS -- 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? - ANS -- By altering their dihydrofolate reducatses
- By altering their dihydropteroate synthase
, Describe the cell membrane disrupter antimicrobials. - ANS -- 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. - ANS -- 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? - ANS -- 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? - ANS -- Steptococcus pyogenes cellulitis, dental
infections, etc.
What are the symptoms of Strep. Pyogenes cellulitis? - ANS -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? - ANS -True
Would you give 2 or more beta-lactams at the same time? - ANS -False
Which Penicillin provides coverage for MRSA? - ANS -Ceftaroline
T/F? When someone comes into the hospital you would start them on penicillin right away? -
ANS -False, you don't give penicillin right away because it has too narrow of a spectrum
Why were semisynthetic penicillins developed? - ANS -Because penicillins became inhibited by
beta lactamase
What does beta lactamase do? - ANS -Enzyme that breaks up the beta lactam ring and makes
penicillin unable to bind to penicillin-binding proteins on bacteria
What was the prototype for semisynthetic penicillins? - ANS -Methicillin
List the extended spectrum penicillins. - ANS -- Aminopenicillins
- Carboxypenicillins
