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Pharmacology > Penicillins, Cephalosporins, and Other β-Lactam Antibiotics > Flashcards

Penicillins, Cephalosporins, and Other β-Lactam Antibiotics Flashcards

1
Q

Β-lactam Antibiotics

A

Penicillins Cephalosporins Carbapenems

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2
Q

MOA of B-lactam antibiotics

A

inhibition of synthesis of the bacterial peptidoglycan cell wall

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3
Q

What is acylated by b-lactam antiobiotics?

A

the transpeptidase via cleavage of the –CO-N- bond of the B-lactam ring - Inhibit the transpeptidation reaction (last step in peptidoglycan synthesis - There are additional, related targets collectively known as Penicillin-binding Protein (PBP) – e.g. Transpeptidase

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4
Q

MECHANISMS OF BACTERIAL RESISTANCE TO PENICILLINS AND CEPHALOSPORINS

A
  1. Mutations -that decrease the affinity of PBPs for the antibiotic
  2. Acquisition of an additional high-molecular-weight PBP (via a transposon) with a very low affinity for all β-lactam antibiotics - Methicillin-resistant Staphylococcus aureus MRSA
  3. Inability of the agent to penetrate to its site of action
  4. Active efflux pumps remove the antibiotic from its site of action before it can act
  5. Destruction of antibiotics enzymatically via the action of β-lactamases - (4 classes: A to D)
  6. Microorganisms adhering to implanted prosthetic devices (e.g. catheters, artificial joints, prosthetic heart valves) -produce biofilms – produce extracellular polysaccharides – less sensitive to antibiotic
  7. Bacteria that survive inside viable cells of the host generally are protected from the action of β-lactam antibiotics.
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5
Q

MRSA MOA

A

Acquisition of an additional high-molecular-weight PBP (via a transposon) with a very low affinity for all β-lactam antibiotics

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6
Q

Highly active against Gram +

A

Penicillin G Penicillin V

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7
Q

Readily hydrolyzed by Penicillinase

A

Penicillin G Penicillin V

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8
Q

Ineffective against S. aureus

A

Penicillin G Penicillin V

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9
Q

First choice for treatment of penicillinase-producing S. aureus and S. epidermidis

A

Penicillinase-resistant Methicillin, Nafcillin, Oxacillin, Cloxacillin, Dicloxacillin (DMONC)

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10
Q

Antimicrobial activity against Gram – organisms (H. influenzae, E. coli & Proteus mirabiis)

A

Ampicillin, Amoxicillin + Clavulanate or Sulbactam (β-lactamase inhibitor)

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11
Q

Antimicrobial activity against Pseudomonas, Enterobacter, Proteus spp

A

Carbenicillin, Carbenicillin indantyl, Ticarcillin

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12
Q

Inferior to Ampicillin against Gram + cocci & Listeria monocytogenes

A

Carbenicillin, Carbenicillin indantyl, Ticarcillin

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13
Q

Less active than Piperacillin against Pseudomonas

A

Carbenicillin, Carbenicillin indantyl, Ticarcillin

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14
Q

Excellent antimicrobial activity against Pseudomonas, Klebsiella, & certain other Gram – microorganisms

A

Mezlocillin, Azlocillin, Piperacillin (MAP)

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15
Q

Retains activity of Ampicillin against Gram + cocci and L. monocytogenes

A

Mezlocillin, Azlocillin, Piperacillin (MAP)

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16
Q

Rheumatic Fever prophylaxis

A

Penicillin G - Gastric pH 2 – destroys antibiotic

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17
Q

More stable in acidic medium: Penicillin V or G?

A

Penicillin V

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18
Q

↓ tubular secretion of Penicillin ↑ plasma concentration

A

Probenecid

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19
Q

T/F: Penicillin G penetrates when meninges are inflamed

A

True

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20
Q

inhibits transport of Penicillin from CSF to bloodstream

A

Probenecid

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21
Q

Pneumococcal Infections

A

Penicillin G - agent of choice

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22
Q

Pneumococcal Pneumonia

A

3rd Generation CEPHALOSPORINS (Ceftriaxome) 20-24 M units of Penicilin G for 7-10 days

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23
Q

Pneumococcal Meningitits

A

Vancomycin + 3rd generation Cephalosporin 20-24 M units for 14 days of Pen G;

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24
Q

Streptococcal Pharyngitis

A

Pen V 500 mg q6 PO for 10 days

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25
Scarlet Fever
Pen V 500 mg q6 PO for 10 days
26
S. Pyogenes (group A β-hemolytic Streptococcus) – cause RHD
Pen V 500 mg q6 PO for 10 days
27
Streptococcal Toxic Shock & Necrotizing Fascitis
Penicillin + Clindamycin
28
Streptococcal Pneumonia, Arthritis, Meningitis & Endocarditis (S. pyogenes)
Pen G 12-20M units IV 2-4 weeks Endocarditis: for 4 weeks
29
Streptococcus viridans
Pen G 12-20 M units IV Pen G for 2 weeks (4 weeks if alone) + Gentamycin 1mg /kg q8
30
Enterococcal endocarditis
Pen G/ Ampicillin + Gentamicin - Pen G 20M units or Ampicillin 12g IV + Gentamicin for 6 weeks
31
Meningococcal
Penicillin
32
Gonococcal
Ceftriaxone
33
Staphylococcal Infections MRSA
Penicillinase producing organism; resistant to Penicillin; Vancomycin, Linezolid, Daptomycin Trimethoprim-Sulfamethoxazole, Doxycycline, Clindamycin
34
10, 20 & Latent Syphilis \< 1 year duration
Pen G Procaine 2.4M units/day IM + Probenecid for 10 days
35
Late latent syphilis, neurosyphilis, CV syphilis
Pen G 20M units for 10 days
36
Congenital Syphilis
Aqueous Pen G 50,000/kg in 2 divided doses or Procaine Pen G 50,000/kg OD for 10 days
37
Treatment for Jarisch-Herxheimer reaction
Aspirin - Therapy w/ Penicillin should NOT be discontinued
38
In Jarisch-Herxheimer reaction, Several hours after the 1st injection of penicillin manifestations
chills, fever, headache, myalgias, and arthralgias
39
Actinomycosis
Pen G
40
Diphtheria
Pen G -Pen G eliminates the carrier state Pen G 2-3M units/day for 10-12 days
41
Clostridial Infections (Gas Gangrene)
Pen G agent of choice as adjunct to antitoxin
42
Fusospirochetal Infection (Trench mouth)
Pen V 500mg q6
43
Rat-bite fever (Spirillum minor, Stretobacillus moniliformis)
Pen G – therapeutic agent of choice
44
Listeria monocytogenes
Pen G & Ampicillin + Gentamicin
45
Lyme disease : early disease
Tetracycline
46
Lyme disease: Severe
Pen g or 3rd gen cephalosporin
47
Penicillinase-resistant penicillins
Oxacillin, Cloxacillin, Dicloxacillin, Nafcillin
48
most active of the penicillinase-resistant penicillins
NAFCILLIN
49
Treatment of staphylococcal meningitis
NAFCILLIN
50
MRSA - resistant to:
Resistance to penicillinase-resistant penicillins & cephalosporins
51
MRSA: Hospital Acquired
resistant to aminoglycosides, tetracyclines, erythromycin, & clindamycin
52
MRSA: Community Acquired
resistant to macrolides Vancomycin (drug of choice) + Rifampin
53
MRSA: Drug of Choice
Vancomycin (drug of choice) + Rifampin
54
AMINOpenicillins
Ampicillin, Amoxicillin, & their Congeners
55
Enterobacteriacea (E. coli)
Ampicillin + Sulbactam (β-lactamase inhibitor) Amoxicillin + Clavulanate
56
Shigellosis
Amoxicillin less effective than Ampicillin for Shigellosis
57
Salmonella
Ampicillin high dose
58
Tx use of Aminopenicillin
1. Upper Respiratory 2. UTI 3. Meningitis 4. Salmonella infection
59
ANTI-PSEUDOMONAL penicillins
Carboxypenicillins (Carbenicillin, Ticarcillin) Ureidopenicillins (Mezlocillin, Piperacillin)
60
supplied as disodium salt; CHF results from excessive Na+
Carbenicillin
61
Broadest antibacterial spectrum of the penicillins
Piperacillin + Tazobactam (β-lactamase inhibitor )
62
UNTOWARD REACTIONS TO PENICILLINS
- Hypersensitivity Reactions - Bone marrow depression - Granulocytopenia - Hepatitis (Oxacillin, Nafcillin) -Pain, Sterile Inflammatory reactions at IM site
63
first source isolated in 1948 by Brotzu from the sea near a sewer outlet off the Sardinian coast
Cephalosporium acremonium
64
Mechanisms of Bacterial Resistance: Cephalosporin
inability of the antibiotic to reach its sites of action \* alterations in the penicillin-binding proteins (PBPs) – antibiotics bind to bacterial enzymes (β-lactamases) that can hydrolyze the β-lactam ring and inactivate the cephalosporin
65
2nd Generation Cephalosporin
65
1st Generation
66
3rd gen
67
4th gen cephalosporin
68
Carbapenems
* Imipenem * Meropenem * Doripenem * Ertapenem * Aztreonam * Broader spectrum of activity * Binds to Penicillin-binding Proteins * Disrupts bacterial cell wall synthesis * Death of susceptible microorganisms * Very resistant to hydrolysis by most β-lactamases
69
β-LACTAMASE INHIBITORS
* CLAVULANIC ACID * SULBACTAM * TAZOBACTAM

Pharmacology (4 decks)

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