GMS 6121 Exam 3 pt. 2 Questions With
Complete Answers
therapeutic index - ANSWER - toxic dose to us/therapeutic dose against bacteria
- high number is good
MIC - ANSWER - minimum inhibitory concentration
- the lowest dose for stasis
Determining how much antibiotics to give and how often based on: - ANSWER - rate of
excretion (kidneys)
- rate of metabolism (liver)
Enzyme that modifies or degrades the antibiotics - ANSWER - β-lactamase (bla gene)
- chloramphenicol acetyl transferase (cat gene)
- aminoglycoside phosphotransferase (aph gene)
PLASMIDS
Inhibits β-lactamase enzyme - ANSWER - clavulanic acid
- bacteria are building bla gene resistance
Alter the target of the antibiotics - ANSWER - spontaneous point mutation most common
- enzymatic modification (erythromycin)
- new biosynthetic pathway (synthesis of D-ala-D-ala precursors that vancomycin cannot
bind to)
- acquire new enzymes that are resistant (MRSA- permanent change in genome
penicillin binding proteins)
, Change flux of antibiotics - ANSWER - pump the antibiotics out of the cell:
- tetracycline resistance pump encoded on tetA gene
- multiple antibiotic resistant (MAR)
Innate resistance to antibiotics - ANSWER - permeability barrier of gram-negatives
(porins)
- lack of peptidoglycan in Mycoplasma (resistant to β-lactam antibiotics)
Spontaneous point mutations - ANSWER - nalidixic acid: DNA gyrase (gyrA gene)
- streptomycin: ribosomal protein (rpsL gene)
- rifampin: RNA polymerase (rpoB)
Chromosomal/spontaneous point mutations - ANSWER - target is changed but it retains
cellular function
Colonized sites - ANSWER - alimentary/intestinal tract
- upper respiratory tract
- distal genitourinary tract
- skin
Normally sterile sites - ANSWER - blood
- CSF
- interstitial fluid and spaces (peritoneal cavity)
- lymph
Exogenous - ANSWER - disease started soon after encounter
Complete Answers
therapeutic index - ANSWER - toxic dose to us/therapeutic dose against bacteria
- high number is good
MIC - ANSWER - minimum inhibitory concentration
- the lowest dose for stasis
Determining how much antibiotics to give and how often based on: - ANSWER - rate of
excretion (kidneys)
- rate of metabolism (liver)
Enzyme that modifies or degrades the antibiotics - ANSWER - β-lactamase (bla gene)
- chloramphenicol acetyl transferase (cat gene)
- aminoglycoside phosphotransferase (aph gene)
PLASMIDS
Inhibits β-lactamase enzyme - ANSWER - clavulanic acid
- bacteria are building bla gene resistance
Alter the target of the antibiotics - ANSWER - spontaneous point mutation most common
- enzymatic modification (erythromycin)
- new biosynthetic pathway (synthesis of D-ala-D-ala precursors that vancomycin cannot
bind to)
- acquire new enzymes that are resistant (MRSA- permanent change in genome
penicillin binding proteins)
, Change flux of antibiotics - ANSWER - pump the antibiotics out of the cell:
- tetracycline resistance pump encoded on tetA gene
- multiple antibiotic resistant (MAR)
Innate resistance to antibiotics - ANSWER - permeability barrier of gram-negatives
(porins)
- lack of peptidoglycan in Mycoplasma (resistant to β-lactam antibiotics)
Spontaneous point mutations - ANSWER - nalidixic acid: DNA gyrase (gyrA gene)
- streptomycin: ribosomal protein (rpsL gene)
- rifampin: RNA polymerase (rpoB)
Chromosomal/spontaneous point mutations - ANSWER - target is changed but it retains
cellular function
Colonized sites - ANSWER - alimentary/intestinal tract
- upper respiratory tract
- distal genitourinary tract
- skin
Normally sterile sites - ANSWER - blood
- CSF
- interstitial fluid and spaces (peritoneal cavity)
- lymph
Exogenous - ANSWER - disease started soon after encounter
