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Micro & Immuno > Antibacterials > Flashcards

Antibacterials Flashcards

1
Q

bacteriostatic

A

inhibits bacterial growth without causing death. MIC= minimum inhibitory concentration.

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2
Q

bactericidal

A

rapidly kills bacteria by disrupting synthesis or integrity of the cell wall. MBC for 99.9% death

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3
Q

5 bactericidal mechanisms of action

A
  • -cell wall synthesis
  • -protein synthesis
  • -nucleic acid synthesis
  • -antimetabolites
  • -bacterial membrane disruption
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4
Q

2 classes of antibiotics that inhibit cell wall synthesis

A

beta-lactams (penicillins, cephalosporins, carbapenems, monobactams) and glycopeptides

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5
Q

Penicillin mechanism

A
  • -bind PBPs to inhibit cell wall synthesis of peptidoglycan layer
  • -beta-lactam ring is antibacterial
  • -side chains dictate spectrum
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6
Q

Penicillin side effects

A

Results from hypersensitivity

  • -Morbilliform rash (most common) due to IgM response
  • -Anaphylaxis (rare) IgE mediated leads to angioedema, bronchospasm, hypotension
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7
Q

Cephalosporin mechanism

A
  • -inhibit peptidoglycan synthesis by binding PBPs

- -compared to penicillin: wider spectrum, can kill many beta-lactamase bacteria, improved pharmacokinetics

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8
Q

Cephalosporin coverage and side effects

A
  • -better coverage of Gram (-) with later generations

- -can be useful for penicillin hypersensitivity unless they have a history of anaphylaxis runs

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9
Q

Carbapenem mechanism

A
  • -inhibit peptidoglycan synthesis by binding PBPs

- -compared to penicillin: wider spectrum, can kill many beta-lactamase bacteria, improved pharmacokinetics

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10
Q

Carbapenem coverage and side effects

A
  • -very wide coverage, antipseudomonal
  • -seizures is main side effect
  • -avoid giving to CNS compromised pts.
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11
Q

Monobactams (aztreonam) mechanism and side effects

A
  • -reserved for penicillin allergic patients
  • -ONLY active against Gram (-) aerobic bacteria
  • -no major side effects
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12
Q

Beta-lactam resistance mechanisms

A

(1) beta-lactamases (degradative enzymes)
(2) PBPs (cell wall resistant transpeptidases)
(3) efflux pumps

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13
Q

Beta-lactamase inhibitor mechanisms

A
  • -weak antibactericidal, must combine with penicillins

- -irreversibly bind/inactivate beta-lactamses of bacteria

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14
Q

Glycopeptide mechanism

A

(Vancomycin)

  • -inhibits cell wall formation by interacting with D-alanine-D-alanine termini of pentapeptide side chains in the cell wall
  • -no beta-lactam cross resistance
  • -ONLY active against Gram (+) organisms
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15
Q

Vancomycin side effects

A
  • -**Red Man’s: histamine release from rapid AB infusion –> anaphylaxis
  • -administer more slowly
  • -neutropenia & nephrotoxicity
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16
Q

Vancomycin resistance

A
  • -molecule is too large to penetrate outer membrane of Gram (-) bacteria
  • -also unable to bind to bacteria from changes in pentapeptide side chain terminus
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17
Q

Protein synthesis inhibitors (30S ribosome)

A
  • -aminoglycosides (streptomycin)

- -tetracyclines

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18
Q

Protein synthesis inhibitors (50S ribosome)

A
  • -clindamycin
  • -macrolides (erythromycin)
  • -chloramphenicol
  • -linezolid
  • -streptogramins (quinupristin/dalfopristin)
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19
Q

Aminoglycoside mechanism

A
  • -Gram (-) rods
  • -irreveribly bind to 30S ribosomes
  • -commonly used in syngery with beta-lactam or vancomycin for Gram(+) treatment
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20
Q

Aminoglycoside side effects

A
  • -nephrotoxicity (dose > 1/day or treatment > 3 days)

- -ototoxicity (often irreversible)

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21
Q

Aminoglycoside resistance

A
  • -*mutation of 30S ribosome binding site
  • -decreased AB uptake
  • -enzymatic modification of AB
  • -efflux pump
22
Q

Tetracyclines mechanism

A
  • -**bacteriostatic binding to 30S ribosome

- -effective against variety of typical and atypical organisms

23
Q

Tetracycline side effects

A
  • -teeth discoloration given to children
  • -brown skin discoloration
  • -dark melanin deposits on skin
24
Q

Tetracyclne resistance

A
  • -decreased penetration into bacteria
  • -efflux pump
  • -*30S ribosome allows binding but protein synthesis continues
25
Q

Macrolide mechanism

A

–**bacteropstatic against atypicals, gram (+), and some mycobacteria

26
Q

Macrolide side effects

A
  • -(enteric like) abdominal cramps, nausea, vomitting, diarrhea
    • V tach with QT prolongation
27
Q

Macrolide resistance

A
  • -*methylation of 50S ribosome binding site
  • -efflux pump
  • -enzyme modification of AB
  • -decreased permeability of outer envelope
28
Q

Lincosamide mechanism

A

(Clindamycin)

  • -**bacteriostatic against Gram (+) AND anaerobes 50S ribosome
  • -used to prevent toxin formation (TSS)
29
Q

Lincosamide side effects

A

(Clindamycin)

  • -20% diarrhea
  • -rare C. difficile colitis
30
Q

Clindamycin resistance

A
  • -alteration of 50S protein receptor
  • -methylation of 50S subunit binding site (**cross-resistance with macrolides)
  • -decreased penetration
31
Q

Oxazolidinones (Linezolid)

A

–**Bacteriostatic against resistant Gram (+) 50S

32
Q

Oxazolidinones (Linezolid) side effects

A
  • -lactic acidososis
  • -neuropathy
  • -cytopenias
33
Q

Chloramphenicol mechanism

A
  • -*static or cidal depending on bacteria
  • -Salmonella
  • -50S ribosome target
34
Q

Chloramphenicol side effects

A

–Disrupts protein synthesis in bone marrow cells

35
Q

Chloramphenicol resistance

A
  • -*production of chloramphenicol acetytransferase, catalyzes AB
  • -decreased permeability
36
Q

Nucleid acid synthesis antibiotics

A
  • -DNA replication: quinolones & metronidazole

- -RNA replication: rifamycins

37
Q

Quinolone mechanism

A
  • -inhibit DNA gyrases -> breaks in DNA

- -active against Gram (+) and (-)

38
Q

Quinolone side effects

A
  • -tendonitis with rupture
  • -headache dizzine, insomnia
  • -QT prolongation
39
Q

Metronidazole mechanism

A
  • -bacteria reduce AB nitro groups resulting in toxic compounds that disrupt DNA
  • -activae against anaerobic bacteria and some parasites
40
Q

Metronidazole side effects

A
  • -neuropathy

- -ataxia, dysarthria, cerebellar dentae lesions

41
Q

Metronidazole resistance

A
  • -reduced AB activation

- -elimination of compounds before DNA interaction

42
Q

Rifamycin mechanism

A
  • -bind to RNA polymerase inhibiting intiation of RNA synthesis
  • -Gram (+) and mycobacteria
  • -single-step mutation resistance
43
Q

Rifamycin side effects

A
  • -1% hepatitis

- -uveitis

44
Q

Antimetabolite antibiotics

A

sulfonamides and trimethoprim

45
Q

Trimethoprim/Sulfonamide mechanism

A
  • -**bacteriostatic that prevents the synthesis of folic acid
  • -active against Gram + and Gram - and some protozoa
  • -Resistance occurs through alteration of the folate pathway
46
Q

TMP-SMX side effects

A

–Enteric
–Hypersensitivity
…

47
Q

Bacterial membrane disruption

A

lipopolypeptides and polymyxins

48
Q

Lipopolypeptide (Daptomycin) mechanism

A
  • -binds to membranes causing rapid depolarization and cell death
  • -Active against Gram (+) and anaerobes
49
Q

Lipopolypeptide (Daptomycin) side effects

A
  • -elevated creatine phosphokinase

- -NO PNEUMONIA (binds surfactant)

50
Q

Polymyxin mechanism, side effect, and resistance

A
  • -acts as a detergent that interacts with phospholipids ad disrupts the cell membrane
  • -active against many GNRs
  • -nephro/neurotoxicity
  • -resistance by decreased permeability

Micro & Immuno (16 decks)

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