PHM203 Exam: Questions With Correct Solutions
(Rated A+)
What are the three parts of the triad of ID Right Ans - - the host, the drug
and the organism
5 types of routine diagnostic tests Right Ans - - culture
- PCR
- serology
- direct detection
- MALD-ITOF (quickly identifying organisms)
MIC Right Ans - minimum inhibitory concentration
- minimum concentration of a drug to cause 99% inhibition of visual growth in
a broth agar medium
MIC breakpoint Right Ans - - concentration of drug required at the site of
infection/lab to cause inhibition of growth or bacterial killing
What are CLSI, QMPLS and EUCAST Right Ans - organizations that
determine the MIC
What organizations are used in canada to determine the MIC Right Ans -
CLSI and EUCAST
What is TAT Right Ans - turn around time
What are 3 examples of lab tests Right Ans - 1. gram stain
(positive/negative)
2. organism identification test (culture, PCR)
3. susceptibility test (disc diffusion)
Sputum sample report - gram stain Right Ans - - first info that comes back
is gram stain (tells you quality and quantity + positive and negative)
Quality - is it pus or epithelial? Right Ans - - less epithelial is good because
it suggests more oral flora and spit
- lots of pus means there is an infection in the lower resp tract
,quantity - sputum sample report Right Ans - 3+ value reported (1+,2+.3+
or scant, few, large)
what do we do once we have the gram stain Right Ans - wait for MALDI-
TOF to determine the type of organism and then results of susceptibility
testing arrives a few days later
true or false: most bacteria take 18-24 hours to grow enough on lab media to
be visible Right Ans - true but can be faster with MALDI-TOF
turnaround timeline Right Ans - - gram stain <24 hours
- then preliminary identification ~24-48 hours
- finally susceptibility results 48+ hours
antibiogram Right Ans - profile of antimicrobial sensitivity
what are antibiograms good for Right Ans - empiric drug choices
what are 5 qualities of an ideal antimicrobial Right Ans - 1. selective
microcidal activity (kill pathogen not host)
2. given orally or IV
3. complementary to host defenses
4. extensive tissue distribution
5. remain active in the presence of organic compounds
bactericidal vs bacteriostatin Right Ans - - bactericidal: causes microbial
death; required for more serious infections
- bacteriostatic: inhibits bacterial growth (doesnt cause death); less serious
infections BUT requires a functioning immune system
5 defense mechanisms of bacteria Right Ans - 1. production of drug
inactivating enzymes (b-lactamases)
2. modification of an existing target (FQ, AMG)
3. acquisition of a target bypass system (additional penicillin binding protein
in mRSA)
4. Reduced cell permeability
5. drug removal from cell (efflux)
,concentration dependent killing Right Ans - - P:MIC, AUC:MIC
- increase [ ] of the drug at site of infection will increase rate (speed) and
extent
- ex. fluoroquinolones
time dependent killing Right Ans - - t>MICC
- increasing the time above the MIC will increase the extent but wont change
the rate(speed)
ex. penicillins
post-antibiotic effect Right Ans - - drug becomes intracellular and works on
protein synthesis
- cant measure concentration of these drugs but have ongoing activity
cell wall agents Right Ans - ß-lactams
5 types of beta lactams Right Ans - 1. penicillin
2. cephalosporin
3. carbapenems
4. vancomycin
5. daptomycin
what are the three main components of penicillin? Right Ans - 1. beta
lactam ring
2. side chain
3. thiazolidine ring
MOA of beta lactams Right Ans - Bind to and inhibit penicillin-binding
proteins (PBPs), which catalyze cross-linking of peptidoglycans
PK/PD of beta lactams Right Ans - - Bactericidal
- time-dependent killing
What does the R functional group do for penicillins? Right Ans - - acid
stability and effect on penicillinases
How do penicillins work? Right Ans - - binds to PBPs, which prevents
cross-linking of peptidoglycan —> blocks cell wall synthesis
, True or false: beta lactams are time-dependent (Time > MIC) killers Right
Ans - true
why do penicillins need to be dosed multiple times a day? Right Ans - low
acid stability --> decreased absorption
True or false: beta lactams are absorbed in the stomach Right Ans - false,
absorbed in the duodenum
True or false: beta lactams are hepatically excreted Right Ans - false,
renally excreted
What 2 beta lactams are not primarily renally excreted Right Ans -
Ceftriaxone and cloxacillin
true or false: all beta lactams require dose adjustments in patients with renal
issues Right Ans - false - exception is ceftriaxone (cloxacillin)
What are side effects of beta-lactams? Right Ans - hypersensitivity
reactions, increased seizure irritability, NVD (nausea, vomiting, diarrhea)
How do beta-lactams cause hypersensitivity reactions? Right Ans -
cleavage of beta-lactam ring to a penicillinoic acid leads to an inert molecule
that has antigenic potential
What secondary infection can occur with the use of beta-lactams? Right
Ans - C. Difficile
*What is the activity of penicillins? Right Ans - beta-lactamase negative
GPC (strep), oral anaerobes, N. meningitidis, syphillis
How does resistance to beta-lactams occur? Right Ans - 1. inactivation by a
beta lactamase
2. modification of target PBPs
3. impaired penetration of drug to reach PBP
4. efflux pumps
True or false: penicillins can kill staph auerus Right Ans - false, staph is a
beta-lactamase positive GPC
(Rated A+)
What are the three parts of the triad of ID Right Ans - - the host, the drug
and the organism
5 types of routine diagnostic tests Right Ans - - culture
- PCR
- serology
- direct detection
- MALD-ITOF (quickly identifying organisms)
MIC Right Ans - minimum inhibitory concentration
- minimum concentration of a drug to cause 99% inhibition of visual growth in
a broth agar medium
MIC breakpoint Right Ans - - concentration of drug required at the site of
infection/lab to cause inhibition of growth or bacterial killing
What are CLSI, QMPLS and EUCAST Right Ans - organizations that
determine the MIC
What organizations are used in canada to determine the MIC Right Ans -
CLSI and EUCAST
What is TAT Right Ans - turn around time
What are 3 examples of lab tests Right Ans - 1. gram stain
(positive/negative)
2. organism identification test (culture, PCR)
3. susceptibility test (disc diffusion)
Sputum sample report - gram stain Right Ans - - first info that comes back
is gram stain (tells you quality and quantity + positive and negative)
Quality - is it pus or epithelial? Right Ans - - less epithelial is good because
it suggests more oral flora and spit
- lots of pus means there is an infection in the lower resp tract
,quantity - sputum sample report Right Ans - 3+ value reported (1+,2+.3+
or scant, few, large)
what do we do once we have the gram stain Right Ans - wait for MALDI-
TOF to determine the type of organism and then results of susceptibility
testing arrives a few days later
true or false: most bacteria take 18-24 hours to grow enough on lab media to
be visible Right Ans - true but can be faster with MALDI-TOF
turnaround timeline Right Ans - - gram stain <24 hours
- then preliminary identification ~24-48 hours
- finally susceptibility results 48+ hours
antibiogram Right Ans - profile of antimicrobial sensitivity
what are antibiograms good for Right Ans - empiric drug choices
what are 5 qualities of an ideal antimicrobial Right Ans - 1. selective
microcidal activity (kill pathogen not host)
2. given orally or IV
3. complementary to host defenses
4. extensive tissue distribution
5. remain active in the presence of organic compounds
bactericidal vs bacteriostatin Right Ans - - bactericidal: causes microbial
death; required for more serious infections
- bacteriostatic: inhibits bacterial growth (doesnt cause death); less serious
infections BUT requires a functioning immune system
5 defense mechanisms of bacteria Right Ans - 1. production of drug
inactivating enzymes (b-lactamases)
2. modification of an existing target (FQ, AMG)
3. acquisition of a target bypass system (additional penicillin binding protein
in mRSA)
4. Reduced cell permeability
5. drug removal from cell (efflux)
,concentration dependent killing Right Ans - - P:MIC, AUC:MIC
- increase [ ] of the drug at site of infection will increase rate (speed) and
extent
- ex. fluoroquinolones
time dependent killing Right Ans - - t>MICC
- increasing the time above the MIC will increase the extent but wont change
the rate(speed)
ex. penicillins
post-antibiotic effect Right Ans - - drug becomes intracellular and works on
protein synthesis
- cant measure concentration of these drugs but have ongoing activity
cell wall agents Right Ans - ß-lactams
5 types of beta lactams Right Ans - 1. penicillin
2. cephalosporin
3. carbapenems
4. vancomycin
5. daptomycin
what are the three main components of penicillin? Right Ans - 1. beta
lactam ring
2. side chain
3. thiazolidine ring
MOA of beta lactams Right Ans - Bind to and inhibit penicillin-binding
proteins (PBPs), which catalyze cross-linking of peptidoglycans
PK/PD of beta lactams Right Ans - - Bactericidal
- time-dependent killing
What does the R functional group do for penicillins? Right Ans - - acid
stability and effect on penicillinases
How do penicillins work? Right Ans - - binds to PBPs, which prevents
cross-linking of peptidoglycan —> blocks cell wall synthesis
, True or false: beta lactams are time-dependent (Time > MIC) killers Right
Ans - true
why do penicillins need to be dosed multiple times a day? Right Ans - low
acid stability --> decreased absorption
True or false: beta lactams are absorbed in the stomach Right Ans - false,
absorbed in the duodenum
True or false: beta lactams are hepatically excreted Right Ans - false,
renally excreted
What 2 beta lactams are not primarily renally excreted Right Ans -
Ceftriaxone and cloxacillin
true or false: all beta lactams require dose adjustments in patients with renal
issues Right Ans - false - exception is ceftriaxone (cloxacillin)
What are side effects of beta-lactams? Right Ans - hypersensitivity
reactions, increased seizure irritability, NVD (nausea, vomiting, diarrhea)
How do beta-lactams cause hypersensitivity reactions? Right Ans -
cleavage of beta-lactam ring to a penicillinoic acid leads to an inert molecule
that has antigenic potential
What secondary infection can occur with the use of beta-lactams? Right
Ans - C. Difficile
*What is the activity of penicillins? Right Ans - beta-lactamase negative
GPC (strep), oral anaerobes, N. meningitidis, syphillis
How does resistance to beta-lactams occur? Right Ans - 1. inactivation by a
beta lactamase
2. modification of target PBPs
3. impaired penetration of drug to reach PBP
4. efflux pumps
True or false: penicillins can kill staph auerus Right Ans - false, staph is a
beta-lactamase positive GPC
