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Questions and Answers
What is the common structural feature of penicillins and cephalosporins?
What is the common structural feature of penicillins and cephalosporins?
Which of the following is NOT a type of β-Lactam antibiotic?
Which of the following is NOT a type of β-Lactam antibiotic?
What is the primary mechanism of action of penicillins and cephalosporins?
What is the primary mechanism of action of penicillins and cephalosporins?
Which of the following antibiotics is available only in oral formulation?
Which of the following antibiotics is available only in oral formulation?
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What is the main classification of antibiotics that includes penicillins and cephalosporins?
What is the main classification of antibiotics that includes penicillins and cephalosporins?
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Which of the following is NOT a cell wall inhibitor?
Which of the following is NOT a cell wall inhibitor?
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Why are piperacillin and ticarcillin often used in combination with penicillinase inhibitors?
Why are piperacillin and ticarcillin often used in combination with penicillinase inhibitors?
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Which of the following penicillins can be administered orally?
Which of the following penicillins can be administered orally?
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What is the effect of food on the absorption of penicillinase-resistant penicillins?
What is the effect of food on the absorption of penicillinase-resistant penicillins?
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What is the role of procaine penicillin G and benzathine penicillin G?
What is the role of procaine penicillin G and benzathine penicillin G?
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Why are the antibacterial effects of piperacillin and ticarcillin limited?
Why are the antibacterial effects of piperacillin and ticarcillin limited?
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What is the effect of oral administration of penicillins on the intestinal flora?
What is the effect of oral administration of penicillins on the intestinal flora?
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What is the primary use of certain penicillins?
What is the primary use of certain penicillins?
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What is a characteristic of methicillin-resistant staphylococcus aureus (MRSA) and S. epidermidis (MRSE)?
What is a characteristic of methicillin-resistant staphylococcus aureus (MRSA) and S. epidermidis (MRSE)?
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What is the result of combining ampicillin with inhibitors of penicillinases?
What is the result of combining ampicillin with inhibitors of penicillinases?
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Which of the following organisms is not susceptible to ampicillin and amoxicillin?
Which of the following organisms is not susceptible to ampicillin and amoxicillin?
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What is the effect of combining ampicillin with aminoglycosides in enterococcal and listerial infections?
What is the effect of combining ampicillin with aminoglycosides in enterococcal and listerial infections?
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Which of the following penicillins has activity against Pseudomonas?
Which of the following penicillins has activity against Pseudomonas?
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What is a characteristic of third-generation cephalosporins?
What is a characteristic of third-generation cephalosporins?
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Which of the following infections is typically treated with second-generation cephalosporins?
Which of the following infections is typically treated with second-generation cephalosporins?
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Which of the following cephalosporins is active against penicillin-resistant pneumococci?
Which of the following cephalosporins is active against penicillin-resistant pneumococci?
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Which of the following is a clinical use of cephalosporins?
Which of the following is a clinical use of cephalosporins?
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Which of the following cephalosporins is used to treat gonorrhea?
Which of the following cephalosporins is used to treat gonorrhea?
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Which of the following organisms is typically susceptible to second-generation cephalosporins?
Which of the following organisms is typically susceptible to second-generation cephalosporins?
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What is the primary mechanism of action of polymyxins?
What is the primary mechanism of action of polymyxins?
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Why is daptomycin not recommended for the treatment of pneumonia?
Why is daptomycin not recommended for the treatment of pneumonia?
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What is the advantage of fosfomycin in treating urinary tract infections?
What is the advantage of fosfomycin in treating urinary tract infections?
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Which of the following bacteria is NOT typically resistant to polymyxins?
Which of the following bacteria is NOT typically resistant to polymyxins?
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What is a potential adverse effect of daptomycin?
What is a potential adverse effect of daptomycin?
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What is the spectrum of activity of daptomycin?
What is the spectrum of activity of daptomycin?
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What is the primary mechanism of action of fosfomycin?
What is the primary mechanism of action of fosfomycin?
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Which of the following bacteria is fosfomycin effective against?
Which of the following bacteria is fosfomycin effective against?
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What is the advantage of daptomycin over vancomycin?
What is the advantage of daptomycin over vancomycin?
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What is the primary use of daptomycin?
What is the primary use of daptomycin?
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Why should daptomycin not be used to treat pneumonia?
Why should daptomycin not be used to treat pneumonia?
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What is the mechanism of action of polymyxins?
What is the mechanism of action of polymyxins?
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Which of the following bacteria is inherently resistant to polymyxins?
Which of the following bacteria is inherently resistant to polymyxins?
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What is the characteristic of polymyxins that makes them concentration-dependent bactericidal agents?
What is the characteristic of polymyxins that makes them concentration-dependent bactericidal agents?
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What is a common side effect of fosfomycin?
What is a common side effect of fosfomycin?
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What laboratory test should be monitored when using daptomycin?
What laboratory test should be monitored when using daptomycin?
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Study Notes
Penicillins
- Susceptible to penicillinases, often used in combination with penicillinase inhibitors (e.g., tazobactam, clavulanic acid) to enhance activity
- Classification: derivatives of 6-aminopenicillanic acid, contain a beta-lactam ring structure essential for antibacterial activity
- Mechanism of Action:
- Binding of the drug to specific enzymes (penicillin-binding proteins [PBPs]) in bacterial cytoplasmic membrane
- Inhibition of transpeptidation reaction that cross-links linear peptidoglycan chain constituents of the cell wall
- Activation of autolytic enzymes that cause lesions in the bacterial cell wall
Narrow-Spectrum Penicillinase-Susceptible Agents
- Penicillin G: prototype, used for infections caused by common streptococci, meningococci, gram-positive bacilli, and spirochetes
- Penicillin V: oral drug used mainly for oropharyngeal infections
- Activity against enterococci is enhanced by coadministration of aminoglycosides
Very-Narrow-Spectrum Penicillinase-Resistant Drugs
- Methicillin, nafcillin, and oxacillin: used for treatment of known or suspected staphylococcal infections
- Methicillin-resistant staphylococcus aureus (MRSA) and S. epidermidis (MRSE) are resistant to all penicillins and often resistant to multiple antimicrobial drugs
Wider-Spectrum Penicillinase-Susceptible Drugs
- Ampicillin and amoxicillin: have a wider spectrum of antibacterial activity than penicillin G
- Clinical uses include indications similar to penicillin G, as well as infections resulting from enterococci, Listeria monocytogenes, Escherichia coli, Proteus mirabilis, Haemophilus influenzae, and Moraxella catarrhalis
- Synergistic with aminoglycosides in enterococcal and listerial infections
- Piperacillin and ticarcillin: have activity against several gram-negative rods, including Pseudomonas, Enterobacter, and in some cases Klebsiella species
- Susceptible to penicillinases, often used in combination with penicillinase inhibitors (e.g., tazobactam, clavulanic acid) to enhance activity
Routes of Administration
- Combination of ampicillin with sulbactam, piperacillin with tazobactam, and anti-staphylococcal penicillins nafcillin and oxacillin: administered intravenously (IV) or intramuscularly (IM)
- Penicillin V, amoxicillin, and dicloxacillin: available only as oral preparations
- Depot forms: procaine penicillin G and benzathine penicillin G administered IM, slowly absorbed into circulation and persist at low levels over a long time period
Absorption
- Most penicillins are incompletely absorbed after oral administration, affecting the composition of the intestinal flora
- Food decreases absorption of penicillinase-resistant penicillins due to stomach acid, so they should be taken on an empty stomach
Other Antibiotics
Fosfomycin
- Excreted by the kidney, with urinary levels exceeding minimal inhibitory concentrations (MICs)
- Indicated for urinary tract infections caused by E. coli or E. faecalis
- Adverse effects include diarrhea, vaginitis, nausea, and headache
Daptomycin
- Bactericidal, novel cyclic lipopeptide with spectrum similar to vancomycin but active against vancomycin-resistant strains of enterococci and staphylococci
- Indicated for treatment of complicated skin and skin structure infections and bacteremia caused by S. aureus
- Inactivated by pulmonary surfactants, so it should never be used in the treatment of pneumonia
- Creatine phosphokinase should be monitored since daptomycin may cause myopathy
Polymyxins
- Cationic polypeptides that bind to phospholipids on the bacterial cell membrane of gram-negative bacteria
- Have a detergent-like effect that disrupts cell membrane integrity, leading to leakage of cellular components and cell death
- Concentration-dependent bactericidal agents with activity against most clinically important gram-negative bacteria, including P. aeruginosa, E. coli, K. pneumoniae, Acinetobacter spp., and Enterobacter spp.
- However, alterations in the cell membrane, lipid polysaccharides allow many species of Proteus and Serratia to be intrinsically resistant
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Description
Test your knowledge on cell wall inhibitors, including penicillins, cephalosporins, and other beta-lactam antibiotics, as well as vancomycin, fosfomycin, and daptomycin. This quiz covers the basics of cell wall inhibitors and their mechanisms of action.