Exam 3 (Antibiotics) Flashcards
Chemical substance produced by a microorganism that inhibits multiplication and growth or kills other microorganisms:
Antibiotic
Chemical substance that is derived from a microorganism or that is produced synthetically that inhibits multiplication and growth or kills microorganisms:
Antimicrobial
antibacterial/antiparasitic/antifungal/antiviral
T/F
All antibiotics are antimicrobials, but not all antimicrobials are antibiotics:
True.
Natural antibiotics tend to be ___toxic and ____ effective than synthetic:
more toxic
less effective
Result with 2 drugs is significantly less than when used individually:
Antagonistic
Do the Vitek2 and E-test provide the MIC:
yes
MIC determines the ______ effect:
bacteriostatic
MBC determines the ____ effect:
bactericidal
____ is found after the MIC using a series of steps/dilutions:
MBC
Broad spectrum antibiotics are effective against both :
Gram+/-
What are the two factors contributing to MRSA:
mecA gene
Beta lactamase
How does the mecA gene contribute to MRSA:
mecA —> PBP—> PBP2a
(pbp= peptide binding protein)
(pbp2a= analog binding)
List the 3 classes of cell wall synthesis inhibitors:
BGF
Beta-lactams
Glycopeptides
Fosfomycins
List the 4 groups of beta-lactams:
PCCM
Penicilllin
Cephalosporin
Carbapenems
Monobactams
The beta-lactam ring is formed by the binding of which two amino acids:
Cysteine and Valine
T/F
Beta-lactams are toxic to humans:
False.
Humans cells lack the murein layer, so are unaffected
Beta-lactamase renders beta-lactams ineffective by:
opening beta-lactam ring, inhibiting the drug from binding to PBP’s
ESBL stands for:
Extended spectrum beta-lactamases
______ are derived from beta-lactamase and confer the bacteria resistance to penicillins and cephalosporins:
ESBL’s
Glycopeptides are only used for Gram___:
Gram+
Why are glycopeptides ineffective against GNB:
They are too large to penetrate outer cell membrane
This cell wall synthesis inhibitor is similar in structure to Penicillins:
Cephalosporins
This cell wall synthesis inhibitor binds to precursors of cell well synthesis:
Glycopeptides
Will beta-lactamase affect glycopeptides:
No
How do cell membrane function inhibitors work:
Disrupt cell membrane causing leakage of ions/macromolecules necessary for cell life
List two examples of Cell membrane function inhibitors:
Polymyxin B
Colistin
_____ act as detergents opening up the cell membrane of primarily Gram- bacteria:
Polymyxin-B
Inhibitors of protein synthesis interfere with protein synthesis in 3 ways:
- interrupt initial formation of proteins
- interfere w/ accurate reading of mRNA
- disrupt ribosomal-mRNA complex
List some drug classes that work by inhibiting protein synthesis:
Aminoglycosides Macrolides Ketolides Tetracyclines Phenicols Glycyclines Oxazolidinones Ansamycins
Are aminoglycosides bacteriostatic or bactericidal:
Bactericidal
This group of protein synthesis inhibitors are monitored via peak and trough values:
Aminoglycosides
Gentamicin belongs to this group:
Aminoglycoside
Macrolides are bacteriostatic by this mechanism:
Inhibit protein synthesis
Erythromycin and Clindamycin belong to this group:
Macrolides
Macrolides are effective against Gram___::
Gram+
macrolides are too large to penetrate the outer membrane of gram- bacteria
This protein synthesis inhibitor is only used in serious Gram- infections, and is monitored carefully for bone marrow aplasia:
Chloramphenicol
Are aminoglycosides effective against anaerobes:
no
Why are tetracyclines contraindicated for use in children under age 8:
Discoloration of teeth
List the 3 groups that inhibit DNA/RNA synthesis:
FMR
Fluoroquinolones
Metronidazole
Rifampin
This DNA/RNA synthesis inhibitor is made from derivatives of naladixic acid and is broad spectrum:
Fluoroquinolones
List the 3 groups that inhibit metabolic processes:
SNT
Sulfonamides
Nitrofurantoin
Trimethoprim
This is a metabolic process inhibitor that is used for urinary tract only:
Nitrofurantoin
This group works by competitive inhibition of folic acid synthesis:
Sulfonamides
Trimethoprim is frequently combined with _____:
Sulfonamides
T/F
Resistance to Rifampin develops quickly and is usually used in combination with others:
True
Are sulfonamides broad spectrum?
Yes
except Pseudomonas is resistant
Kirby Bauer disk diffusion testing utilizes what type of agar:
Mueller-Hinton
Why is constant agar depth important with Kirby Bauer testing, what results from too deep, too thin?
Too deep= smaller zones, false R
Too thin= larger zones, false S
Why is it important to use McFarland Standard, what results from being too light, too heavy?
Too light= false S
Too heavy= false R
For Kirby Bauer disk diffusion, disks must be applied within ___ minutes of streakin plate:
15 minutes
Incubate plates at ____C for Kirby Bauer disk diffusion:
35 C
Does Kirby Bauer testing provide MIC:
no.
e test and vitek do
How do you report results of Kirby Bauer disk testing:
Sensitive
Intermediate
Resistant
T/F
In clinical setting, the interpretive results of the Kirby bauer test (S/I/R) provide necessary amount of information for clincians to treat patients MOST of the time:
True
This is a gradient diffusion method using plastic strips containing varying concentrations of an antimicrobial, does provide MIC:
E-test
Another name for the Serum bacteriocidal test (SBT):
Schlichter test
This test is used to measure ATB activity in the patient’s serum, and determines if treatment is effective:
Schlichter test
T/F
Two serum specimens are required for Schlichter test, and it provides both MIC and MBC:
True
_____ resistance is when changes in cell structure or physiology resulting in less susceptibility than previously observed:
Biologic
This type of resistance results from physical/chemical characteristics of the environment:
Environmentally mediated resistance
What are some contributing factors of environmentally mediated resistance:
pH changes
anaerobic atmosphere
Cation concentration (Mg and Ca)
Thymine/Thymidine content
How does a decrease in pH affect erythromycin and aminoglycoside activity:
Decreases activity
pH increase_______ tetracycline activity:
decreases
Anaerobic conditions decreases _______ activity:
aminoglycoside
If cations outcompete the antibiotic for the negatively charged sites, _____ antibiotic will be taken up:
Less
Thymidine interferes with antibiotics targeting _____ synthesis such as ______:
folic acid
sulfonamides
List the 4 types of resistance:
BCEM
Biologic
Clinical
Environmentally mediated
Microbial mediated
This type of resistance is defined as intrinsic/natural/consistently inherited resistance resulting from normal genetic, structural, physiologic state of the organism:
Microbial mediated resistance
What are the two types of microbial mediated resistance:
Natural/inherited
Acquired
Defined as a resistance to certain antibiotics expressed by a subset of a microbial population that is generally considered to be susceptible to these antibiotics according to traditional in-vitro susceptibility testing:
Heteroresistance
List two examples of heteroresistance:
VISA
VRSA
If an ESBL is detected, all penicillins, cephalosporins, and aztreonam should be reported as ______:
Resistant
VISA/VRSA are susceptible to:
daptomycin
rifampin
tetracycline
These resistant organisms are treated with streptogramins and oxazolidinones:
VRE’s
These are enzymes that mediate resistance to extended spectrum cephalosporins and monobactams, but do not affect cephamycins:
ESBL’s
_____ are typically effective for treating ESBL’s and have been considered a first line of defense:
Carbapenums
CRE stands for:
Carbapenum resistant Enterococci
they have carbapenumases
ESBL’s are produced by Gram- rods of ________:
Enterobacteriaceae
VRSA emerged from the exchange of genetic material from _____ to _____:
VRE
MRSA
This test is for macrolide inducible resistance to clindamycin:
D-test
A positive D test appears as:
A ‘D’ shape surrounding the clindamycin disk
A positive D test indicates:
the presence of macrolide inducible resistance to clindamycin produced by an inducible methylase that alters the common ribosomal binding site for macrolides, clindamycin, and the group B Streptogramins.
Biologic antimicrobials are most often derived from this source:
fungals
Result with 2 drugs is greater than the response of each drug separately:
synergystic
Glycopeptides and bacitracin are only effective against _______:
Gram+ bacteria
Polymyxins are usually only effective against ______:
Gram- bacteria
________ and ______ are only effective against aerobic organisms, while ______ are generally only effective for anaerobes:
Aminoglycosides/Sulfonamides
Nitroimidazoles
The structure of ____ vary by sides chains off basic structure:
aminoglycosides
T/F
Beta-lactams can target both Gram+/- bacteria:
True, but varies depending on specific antibiotic
Are beta-lactams bacteriostatic or bactericidal:
Bactericidal
Beta lactam ring binds to _____, inhibiting its’ action
PBP
Is beta-lactamase produced by Gram+ or Gram-:
Both
ESBL’s are derived from _____, and confer the bacterial resistance to ____ and ____:
beta-lactamase
penicillins and cephalosporins
Polymyxins have both ____ and ____ effects:
bactericidal
Bacteriostatic
These may be used as a last resort when bacteria such as Pseudomonas aeruginosa are resistant to other empirical treatments:
Polymyxin B and Colistin
inhibitors of cell membrane function
List the inhibitors of cell membrane function, and if they are more active against Gram + or -:
Polymyxin B
Colistin
Gram-
are glycopeptides beta-lactams:
no
Glycopeptides are only used for Gram____:
Gram+
Why don’t glycopeptides work on Gram-:
too larger to penetrate outer cell membrane
Vancomycin is what kind of drug:
Glycopeptide
Vancomycin works on Gram___:
Gram+
is a glycopeptide
These drugs bind to precursors of cell wall synthesis:
Glycopeptides
These are structurally similar to beta-lactams:
cephalosporins
This group of antibiotics has limited tissue distribution and requires elimination via the kidneys:
aminoglycosides
Gentamicin, Tobramycin, Amikacin are examples of :
aminoglycosides
Aminoglycosides are active against Gram___:
Gram+/-
Are aminoglycodes effective against anaerobes?
no
Aminoglycosides are often used in combination with ______ or ______ for more rapid killing:
beta-lactams
glycopeptides
Macrolides are bacteriostatic or bactericidal?
bacteriostatic
T/F
Erythromycin and Clindamycin work by protein synthesis inhibition:
True
This protein synthesis inhibitor is broad spectrum, bacteriostatic, effective against Gram+/- and intracellular bacterial pathogens such as chlamydia and rickettsia:
Tetracycline
Are fluoroquinolones broad or narrow spectrum:
broad
This inhibitor of DNA/RNA synthesis is active against Gram- anaerobes:
Metronidazole
List the 3 drugs that interfere with enzymes necessary for DNA replication/transcription:
Fluoroquinolones
Metronidazole
Rifampin
Why is the folic acid pathway important in microbes:
because it produces precursors for DNA synthesis
Which inhibitor of folic acid synthesis works via competitive inhibition of folic acid synthesis:
Sulfonamides
Sulfonamides are broad spectrum, but ____is resistant to them:
Pseudomonas
These are often combined with sulfonamides:
Trimethoprin
List some of the side effects of metabolic process inhibitors:
(FMR)
nausea
nephrotoxicitiy
bone marrow toxicity
allergic rxns
_________ monitors the evolution of resistance and helps drive new drug research:
Susceptibility testing
T/F
Mueller-Hinton agar is used for Kirby Bauer testing because of it’s well defined chemical composition, constant and reproducible, buffered to prevent pH change, and it is not antagonistic toward antibiotic activity:
True
In Kirby Bauer testing, plates are incubated at this temp, and checked after ___ hours:
35 C
16-18 hours
This may be used to determine MIC when you have fastidious or slow growing organisms that do not perform well using automated methods:
E-test
This test measures antibiotic activity in the patient’s serum:
Schlichter test (SBT)
In the Schlichter test, the trough specimen is collected ____ before the next dose, and the peak specimen is collected ____ after dose when concentration is highest, dilutions of each specimen are set up and inoculated with bacterial isolate from patient and incubated overnight:
Tough: 15 min before next dose
Peak: 30-60 mins after dose
T/F
The Schlichter test provides both the MIC and MBC:
True
Tetracycline works best as pH ____:
decreases
Aminoglycosides work best as pH ____:
increases
Aminoglycosides have net____ charge, Pseudomonas has a net ___ charge, and are affected by Cations:
net + charge
net - charge
Intrinsic/natural/consistently inherited resistance, results from normal genetic, structural, physiologic state of the organism:
microbial mediated resistance
Gram- are resistant to macrolides due to ____:
size
What are two examples of heteroresistance:
VISA
VRSA
Does Pseudomonas aeruginosa produce ESBL’s?
yes
ESBL’s provide resistance to several beta lactam antibiotics, including ___, ___, and ____:
penicillins
cephalosporins
monobactams
Klebsiella pneumoniae and E. coli both have ____strains:
CRE
carpapenem resistant enterobacteriaceae
