NSC 830 EKU Pharmacology-Antibiotics
Exam Questions With Correct Answers
Narrow |spectrum
-Treats |limited |# |of |organisms
-Less |likely |to |disrupt |normal |flora
-Used |when |organism |has |been |identified
Extended |spectrum
-Treats |multiple |organisms
-More |likely |to |disrupt |normal |flora
-Used |when |specific |causative |organism |is |unknown
Gram-positive |bacteria
-bacteria |that |give |a |positive |result
in |the |gram-stain |test. |Gram-positive |bacteria |take |up |the |crystal |violet |stain |used |in |the |test, |
and |then |appear |to |be |purple-colored |when |seen |through |a |microscope. |This |is |because |the |
thick |peptidoglycan |layer |in |the |bacterial |cell |wall
retains |the |stain |after |it |is |washed |away |from |the |rest |of |the |sample, |in |the |decolorization |
stage |of |the |test.
-Despite |their |thicker |peptidoglycan |layer, |gram-positive |bacteria |are |more |receptive |to |
antibiotics |than |gram-negative, |due |to |the |absence |of |the |outer |membrane.
-Gram |+ |had |a |thick |peptidoglycan |layer |in |their |cell |wall |(stain |purple)
Examples |of |Gram-positive |bacteria
• |Group |A |beta-hemolytic |streptococci
• |Streptococcus |pneumonia
Gram-negative |bacteria
-cannot |retain |the |violet |stain |after |the
decolorization |step; |alcohol |used |in |this |stage |degrades |the |outer |membrane |of |gram-negative
|cells |making |the |cell |wall |more |porous
and |incapable |of |retaining |the |crystal |violet |stain. |-Their |peptidoglycan |layer |is |much |thinner |
and |sandwiched |between |an |inner |cell |membrane |and |a |bacterial |outer |membrane, |causing |
,them |to |take |up |the |counterstain |(safranin |or |fuchsine) |and |appear |Red |or |Pink
-Gram |- |had |a |thin |peptidoglycan |layer, |but |has |an |outer |membrane |(stain |red/pink)
Examples |of |Gram-negative |bacteria
• |Haemophilus |influenza
• |Neiserria |gonococcus
Atypical |bacteria
-bacteria |that |do |not |color |with |gram-staining, |but |remain |colorless: |they |are |neither |gram-
positive |nor |gram-negative.
-The |atypical |organisms |lack |a |peptidoglycan |layer |so |do |not |retain |crystal |violet |or |safranin,
resulting |in |no |color
-Peptidoglycans |are |the |site |of |action |of |beta-lactam |antibiotics |such |as |penicillins |and |
cephalosporins, |so |atypical |bacteria |are |naturally |resistant |to |these |drugs, |which |in |this |sense
also |makes |them |"atypical" |in |the |treatment |of |their |infections. |Macrolides |such |as |
erythromycin |however, |are |usually |effective.
Examples |of |Atypical |bacteria
• |Chlamydia |pneumoniae
• |Mycoplasma |pneumoniae
• |Legionella
Drug |Resistant |Strep |Pneumoniae |(DRSP) |risk |factors
• |Recent |antibiotic |use
• |Older |(>65 |yo)
• |Multiple |comorbidities |(COPD, |DM, |HF, |renal |failure)
• |Daycare |worker
• |Alcoholism
• |Immunosuppressed |(including |chronic |corticosteroid |use |>10 |mg/day |long |term)
Drug |Resistant |Strep |Pneumoniae |(DRSP) |Treatment
• |High |dose |amoxicillin |(3-4 |g/day)
• |Respiratory |fluoroquinolones: |moxifloxacin, |gemifloxacin, |levofloxacin |(broad |spectrum)
• |telithromycin |(Ketek) |- |use |limited |due |to |hepatotoxicity
*this |bacteria |wont |be |suseptible |to |regular |AB |doses
Other |factors |to |consider |when |determining |drug |selection
, • |Allergy |history
• |Penicillins |-risk |of |cross-allergy |to |cephalosporins
• |Age
• |Renal |function |- |neonates |& |elderly
• |Pregnancy
• |Example: |Contraindicated: |tetracyclines |(tetrogenic), |fluoroquinolone |(interfere |w |joints |and |
cartilidge/bone |growth
-Immunocompromised |status: |Immunomompromised |require |bactericidals |& |extended |
therapy
• |Affordability: |PCNs |inexpensive
• |Taste |& |convenience-Liquid
• |Number |of |times |of |dosing/day
What |is |Bacteriostatic-
Restrains |reproduction |of |bacteria |(arrest |the |growth)
*would |need |a |good |immune |sx |for |the |AB |to |work-not |be |immunocomprimised
What |is |Bactericidal
Kills |the |bacteria
Minimum |Inhibitory |Concentration |(MIC)
• |Lowest |concentration |of |an |antimicrobial |that |will |inhibit |visible |growth |of |a |microorganism |
after |overnight |incubation |under |standard |conditions
Antibiotics |usually |dosed |at |level |to |2-4 |times |MIC
• |"overkill" |refers |to |the |amount |to |allow |for |variations |in |absorption, |distribution
Beta-Lactam |Antibiotics |Include |which |meds |for |primary |and |hospital
1. |Primary |care: |penicillins |&
2. |cephalosporins
Hospital: |3. |Monobactams |&
4. |carbapenems
-These |antibiotics |have |a |beta |lactam |ring |that |is |part |of |their |chemical |Structure
What |is |the |beta-lactum |ring
-The |beta-lactam |ring |works |by |disrupting |the |biosynthesis |of |the |bacterial |cell |wall
-Several |bacteria |produce |beta-lactamase |enzymes |that |open |the |beta-lactam |ring |&
inactivate |the |antibiotic
-Intact |ring |essential |for |antibacterial |activity
Exam Questions With Correct Answers
Narrow |spectrum
-Treats |limited |# |of |organisms
-Less |likely |to |disrupt |normal |flora
-Used |when |organism |has |been |identified
Extended |spectrum
-Treats |multiple |organisms
-More |likely |to |disrupt |normal |flora
-Used |when |specific |causative |organism |is |unknown
Gram-positive |bacteria
-bacteria |that |give |a |positive |result
in |the |gram-stain |test. |Gram-positive |bacteria |take |up |the |crystal |violet |stain |used |in |the |test, |
and |then |appear |to |be |purple-colored |when |seen |through |a |microscope. |This |is |because |the |
thick |peptidoglycan |layer |in |the |bacterial |cell |wall
retains |the |stain |after |it |is |washed |away |from |the |rest |of |the |sample, |in |the |decolorization |
stage |of |the |test.
-Despite |their |thicker |peptidoglycan |layer, |gram-positive |bacteria |are |more |receptive |to |
antibiotics |than |gram-negative, |due |to |the |absence |of |the |outer |membrane.
-Gram |+ |had |a |thick |peptidoglycan |layer |in |their |cell |wall |(stain |purple)
Examples |of |Gram-positive |bacteria
• |Group |A |beta-hemolytic |streptococci
• |Streptococcus |pneumonia
Gram-negative |bacteria
-cannot |retain |the |violet |stain |after |the
decolorization |step; |alcohol |used |in |this |stage |degrades |the |outer |membrane |of |gram-negative
|cells |making |the |cell |wall |more |porous
and |incapable |of |retaining |the |crystal |violet |stain. |-Their |peptidoglycan |layer |is |much |thinner |
and |sandwiched |between |an |inner |cell |membrane |and |a |bacterial |outer |membrane, |causing |
,them |to |take |up |the |counterstain |(safranin |or |fuchsine) |and |appear |Red |or |Pink
-Gram |- |had |a |thin |peptidoglycan |layer, |but |has |an |outer |membrane |(stain |red/pink)
Examples |of |Gram-negative |bacteria
• |Haemophilus |influenza
• |Neiserria |gonococcus
Atypical |bacteria
-bacteria |that |do |not |color |with |gram-staining, |but |remain |colorless: |they |are |neither |gram-
positive |nor |gram-negative.
-The |atypical |organisms |lack |a |peptidoglycan |layer |so |do |not |retain |crystal |violet |or |safranin,
resulting |in |no |color
-Peptidoglycans |are |the |site |of |action |of |beta-lactam |antibiotics |such |as |penicillins |and |
cephalosporins, |so |atypical |bacteria |are |naturally |resistant |to |these |drugs, |which |in |this |sense
also |makes |them |"atypical" |in |the |treatment |of |their |infections. |Macrolides |such |as |
erythromycin |however, |are |usually |effective.
Examples |of |Atypical |bacteria
• |Chlamydia |pneumoniae
• |Mycoplasma |pneumoniae
• |Legionella
Drug |Resistant |Strep |Pneumoniae |(DRSP) |risk |factors
• |Recent |antibiotic |use
• |Older |(>65 |yo)
• |Multiple |comorbidities |(COPD, |DM, |HF, |renal |failure)
• |Daycare |worker
• |Alcoholism
• |Immunosuppressed |(including |chronic |corticosteroid |use |>10 |mg/day |long |term)
Drug |Resistant |Strep |Pneumoniae |(DRSP) |Treatment
• |High |dose |amoxicillin |(3-4 |g/day)
• |Respiratory |fluoroquinolones: |moxifloxacin, |gemifloxacin, |levofloxacin |(broad |spectrum)
• |telithromycin |(Ketek) |- |use |limited |due |to |hepatotoxicity
*this |bacteria |wont |be |suseptible |to |regular |AB |doses
Other |factors |to |consider |when |determining |drug |selection
, • |Allergy |history
• |Penicillins |-risk |of |cross-allergy |to |cephalosporins
• |Age
• |Renal |function |- |neonates |& |elderly
• |Pregnancy
• |Example: |Contraindicated: |tetracyclines |(tetrogenic), |fluoroquinolone |(interfere |w |joints |and |
cartilidge/bone |growth
-Immunocompromised |status: |Immunomompromised |require |bactericidals |& |extended |
therapy
• |Affordability: |PCNs |inexpensive
• |Taste |& |convenience-Liquid
• |Number |of |times |of |dosing/day
What |is |Bacteriostatic-
Restrains |reproduction |of |bacteria |(arrest |the |growth)
*would |need |a |good |immune |sx |for |the |AB |to |work-not |be |immunocomprimised
What |is |Bactericidal
Kills |the |bacteria
Minimum |Inhibitory |Concentration |(MIC)
• |Lowest |concentration |of |an |antimicrobial |that |will |inhibit |visible |growth |of |a |microorganism |
after |overnight |incubation |under |standard |conditions
Antibiotics |usually |dosed |at |level |to |2-4 |times |MIC
• |"overkill" |refers |to |the |amount |to |allow |for |variations |in |absorption, |distribution
Beta-Lactam |Antibiotics |Include |which |meds |for |primary |and |hospital
1. |Primary |care: |penicillins |&
2. |cephalosporins
Hospital: |3. |Monobactams |&
4. |carbapenems
-These |antibiotics |have |a |beta |lactam |ring |that |is |part |of |their |chemical |Structure
What |is |the |beta-lactum |ring
-The |beta-lactam |ring |works |by |disrupting |the |biosynthesis |of |the |bacterial |cell |wall
-Several |bacteria |produce |beta-lactamase |enzymes |that |open |the |beta-lactam |ring |&
inactivate |the |antibiotic
-Intact |ring |essential |for |antibacterial |activity
