Pharm Lecture Flashcards AI

Antimicrobials

  • Gram-positive bacteria: Possess a thick peptidoglycan cell wall, consisting of approximately 30 layers, situated on a single plasma membrane (phospholipid bilayer). Examples include Streptococcus pneumoniae, Staphylococcus aureus, and Clostridium difficile.

  • Gram-negative bacteria: Characterized by a thinner peptidoglycan layer positioned between two phospholipid bilayer membranes. This dual-membrane structure can make Gram-negative bacteria more resistant to antibiotics. Examples include Salmonella typhi, Neisseria gonorrhea, and Brucella melitensis.

  • Bactericidal: Antimicrobials that directly kill bacteria.

  • Bacteriostatic: Antimicrobials that inhibit bacterial growth, allowing the immune system time to clear the infection.

Penicillins

  • Examples: Penicillin G, Penicillin VK, Amoxicillin

  • Mechanism of Action (MOA): Inhibits bacterial cell wall synthesis by inhibiting transpeptidase, the enzyme responsible for linking peptidoglycans.

  • Action: Bactericidal

  • Spectrum of Activity: Effective against Gram-positive bacteria.

  • Beta-Lactam Antibiotic: Penicillins are beta-lactam antibiotics, often administered with beta-lactamase inhibitors like clavulanic acid to prevent antibiotic resistance.

  • Adverse Effects: Hypersensitivity reactions, such as skin rash, are common.

Cephalosporins

  • Examples: Cephalexin, Cefaclor, Ceftriaxone

  • MOA: Inhibits bacterial cell wall synthesis.

  • Action: Bactericidal

  • Spectrum of Activity: Effective against Gram-positive bacteria and some Gram-negative bacteria, exhibiting a broader spectrum compared to penicillins.

  • Beta-Lactam Antibiotic: Cephalosporins are beta-lactam antibiotics, sometimes administered with beta-lactamase inhibitors.

  • Generations: Multiple generations exist, each with increased ability to combat Gram-negative bacteria, resistance to beta-lactamase, and ability to penetrate the central nervous system (CNS), useful for treating meningitis.

Vancomycin

  • MOA: Inhibits bacterial cell wall synthesis.

  • Action: Bactericidal

  • Spectrum of Activity: Effective against Gram-positive bacteria, particularly against serious bacterial infections like methicillin-resistant Staphylococcus aureus (MRSA).

  • Non-Beta-Lactam Antibiotic: Vancomycin is not a beta-lactam and serves as an alternative for patients with beta-lactam allergies.

  • Administration: Must be injected slowly to avoid

Antimicrobials

  • Gram-positive bacteria: Characterized by a thick peptidoglycan cell wall that consists of approximately 30 layers, situated above a single plasma membrane which is a phospholipid bilayer. This robust structure provides a protective environment for these bacteria. Common examples include Streptococcus pneumoniae, which is a leading cause of bacterial pneumonia; Staphylococcus aureus, often responsible for skin infections and food poisoning; and Clostridium difficile, known for causing severe gastrointestinal conditions.

  • Gram-negative bacteria: These have a thinner peptidoglycan layer, typically only a few layers thick, sandwiched between two phospholipid bilayer membranes, making them inherently more resilient to certain antibiotics due to their outer membrane. Examples include Salmonella typhi, the causative agent of typhoid fever; Neisseria gonorrhea, which causes gonorrhea; and Brucella melitensis, responsible for brucellosis, an infection affecting livestock that can be transmitted to humans.

  • Bactericidal: Refers to a class of antimicrobials that directly kill bacteria by targeting vital cellular components, such as the cell wall, nucleic acids, or protein synthesis machinery, thereby leading to cell lysis and death.

  • Bacteriostatic: These antimicrobials inhibit bacterial growth without killing them outright, giving the immune system an opportunity to combat the infection. This mechanism is essential in situations where the host immune response is strong enough to clear the infection once growth is halted.

Penicillins

  • Examples: Commonly used penicillins include Penicillin G and Penicillin VK, which are effective against a variety of infections, and Amoxicillin, a widely prescribed oral antibiotic for various bacterial infections.

  • Mechanism of Action (MOA): Penicillins inhibit bacterial cell wall synthesis by blocking transpeptidase, an enzyme crucial for forming cross-links in the bacterial cell wall structure, resulting in cell wall instability and eventual cell death.

  • Action: Classified as bactericidal due to their ability to kill actively dividing bacteria.

  • Spectrum of Activity: Primarily effective against Gram-positive bacteria, especially cocci and some rods, but limited against most Gram-negative bacteria.

  • Beta-Lactam Antibiotic: As beta-lactam antibiotics, penicillins are often prescribed in conjunction with beta-lactamase inhibitors like clavulanic acid to enhance efficacy against resistant strains of bacteria that produce beta-lactamase enzymes.

  • Adverse Effects: Common adverse effects include hypersensitivity reactions such as skin rashes or anaphylaxis in sensitive individuals. Gastrointestinal disturbances, such as diarrhea, can also occur, particularly with broad-spectrum formulations.

Cephalosporins

  • Examples: Well-known cephalosporins include Cephalexin, a first-generation cephalosporin widely used for skin infections; Cefaclor, used for respiratory tract infections; and Ceftriaxone, a third-generation cephalosporin effective against more resistant Gram-negative pathogens.

  • MOA: Similar to penicillins, cephalosporins interrupt bacterial cell wall synthesis, leading to cell lysis.

  • Action: Also classified as bactericidal, targeting actively growing bacteria.

  • Spectrum of Activity: Exhibit a broader spectrum compared to penicillins, being effective against both Gram-positive and some Gram-negative bacteria.

  • Beta-Lactam Antibiotic: Like penicillins, cephalosporins are beta-lactam antibiotics and may also be used with beta-lactamase inhibitors for resistant strains.

  • Generations: Multiple generations exist, with each newer generation exhibiting increased resistance to beta-lactamase, improved efficacy against Gram-negative bacteria, and enhanced ability to penetrate the central nervous system, making them suitable for treating central nervous system infections, including meningitis.

Vancomycin

  • MOA: Vancomycin inhibits bacterial cell wall synthesis by binding to the D-Ala-D-Ala terminus of the peptidoglycan precursors, preventing their incorporation into the growing cell wall, effectively halting cell wall production.

  • Action: This antibiotic is also bactericidal, particularly effective against organisms that are resistant to other antibiotics.

  • Spectrum of Activity: Primarily targets Gram-positive bacteria, making it particularly important in treating serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and other resistant strains.

  • Non-Beta-Lactam Antibiotic: Distinct from the beta-lactam antibiotics, vancomycin offers an alternative for patients with documented allergies to beta-lactams or in cases of resistant Gram-positive infections.

  • Administration: Generally administered intravenously for systemic infections, slow infusion is necessary to avoid potential side effects such as Red Man Syndrome, characterized by an infusion-related reaction resulting in flushing and rash.