Antibiotics Flashcards
What are antibiotics?
Antibiotics are substances derived from microorganisms or synthesized chemically that inhibit the growth of bacteria or kill them outright.
What is the primary mode of action of antibiotics?
The primary mode of action of antibiotics is to inhibit bacterial cell wall synthesis, protein synthesis, nucleic acid synthesis, or disrupt bacterial cell membranes.
What is the difference between bactericidal and bacteriostatic antibiotics?
Bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics inhibit bacterial growth without killing them.
Name the four main targets of antibiotics.
The four main targets of antibiotics are cell wall synthesis, protein synthesis, nucleic acid synthesis, and cell membrane integrity.
What is the difference between narrow-spectrum and broad-spectrum antibiotics?
Narrow-spectrum antibiotics target specific types of bacteria, while broad-spectrum antibiotics are effective against a wide range of bacteria, including both gram-positive and gram-negative bacteria.
What are the differences between gram-positive and gram-negative bacteria in terms of their cell wall structure?
Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, while gram-negative bacteria have a thin layer of peptidoglycan surrounded by an outer membrane containing lipopolysaccharides.
What is the mechanism of action of beta-lactam antibiotics?
Beta-lactam antibiotics inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing the cross-linking of peptidoglycan strands. (Inhibit transpeptidation)
Name a beta-lactam antibiotic.
Penicillin, Carbapenem, cephalosporins and monobactams
What is the role of the enzyme beta-lactamase in antibiotic resistance?
Beta-lactamase breaks down beta-lactam antibiotics, rendering them ineffective against bacteria that produce this enzyme.
Which class of antibiotics inhibits protein synthesis by binding to the 30S ribosomal subunit?
Aminoglycosides, such as gentamicin and streptomycin, bind to the 30S ribosomal subunit to inhibit protein synthesis. Tetracylines as well.
How do tetracyclines inhibit bacterial protein synthesis?
Tetracyclines inhibit protein synthesis by binding to the 30S ribosomal subunit and blocking the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.
Name an antibiotic that targets the 50S ribosomal subunit.
Macrolides like: Erythromycin
Lincosamides: clindamycin ( also 23 ribosomal subunit)
How does erythromycin inhibit bacterial protein synthesis?
Erythromycin binds to the 50S ribosomal subunit and prevents the translocation of the growing peptide chain, inhibiting protein synthesis.
What is the mechanism of action of fluoroquinolone antibiotics?
Fluoroquinolones inhibit bacterial DNA synthesis by targeting DNA gyrase and topoisomerase IV, enzymes involved in DNA replication and repair.
Name a fluoroquinolone antibiotic.
Ciprofloxacin is a fluoroquinolone antibiotic.
How do sulfonamides inhibit bacterial growth?
Sulfonamides inhibit bacterial folate synthesis by competing with para-aminobenzoic acid (PABA) for the active site of dihydropteroate synthase, an enzyme involved in folate synthesis.
What is the mechanism of action of trimethoprim?
Trimethoprim inhibits bacterial folate synthesis by blocking dihydrofolate reductase, an enzyme involved in the conversion of dihydrofolate to tetrahydrofolate.
Name an antibiotic that disrupts bacterial cell membrane integrity.
Polymyxin B is an antibiotic that disrupts bacterial cell membrane integrity. (detergent like) & daptomycin
How does polymyxin B exert its antibacterial effect?
Polymyxin B binds to the lipid component of bacterial cell membranes, disrupting membrane integrity and causing leakage of intracellular contents.
What are the major adverse effects associated with aminoglycoside antibiotics?
Major adverse effects of aminoglycoside antibiotics include nephrotoxicity and ototoxicity.
Which antibiotic class is contraindicated during pregnancy due to the risk of tooth discoloration and inhibition of bone growth in the fetus?
Tetracyclines are contraindicated during pregnancy due to the risk of tooth discoloration and inhibition of bone growth in the fetus.
Which antibiotics are commonly used to treat urinary tract infections?
Fluoroquinolones, such as ciprofloxacin and levofloxacin, and sulfonamides, such as trimethoprim-sulfamethoxazole (TMP-SMX), are commonly used to treat urinary tract infections.Fosfomycin, Nitrofurantoin
What is the mechanism of action of macrolide antibiotics?
Macrolide antibiotics inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing the translocation of the growing peptide chain.
Which antibiotics are considered first-line treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections?
Vancomycin and daptomycin are considered first-line treatment for MRSA infections.
What is the mechanism of action of vancomycin?
Vancomycin inhibits bacterial cell wall synthesis by binding to the D-alanine-D-alanine terminus of peptidoglycan precursors, preventing their incorporation into the cell wall.
How does bacterial resistance to vancomycin develop?
Bacterial resistance to vancomycin can develop through the acquisition of the VanA gene, which modifies the D-alanine-D-alanine terminus of peptidoglycan precursors, reducing vancomycin binding affinity.
What is the primary mechanism of resistance to fluoroquinolone antibiotics?
Resistance to fluoroquinolone antibiotics primarily occurs through mutations in DNA gyrase and topoisomerase IV, reducing drug binding affinity.
What is the role of efflux pumps in antibiotic resistance?
Efflux pumps actively extrude antibiotics from bacterial cells, reducing intracellular drug concentrations and conferring resistance.
How does antibiotic stewardship contribute to combating antibiotic resistance?
Antibiotic stewardship promotes the appropriate use of antibiotics, minimizing unnecessary antibiotic prescriptions and reducing the emergence of antibiotic-resistant bacteria.
Which antibiotic class is commonly associated with pseudomembranous colitis?
Clindamycin is commonly associated with pseudomembranous colitis caused by Clostridium difficile overgrowth
Which antibiotics are commonly used to treat anaerobic bacterial infections?
Metronidazole, clindamycin carbapenems (imipenem, meropenem and ertapenem) and chloramphenicol,are commonly used to treat anaerobic bacterial infections.
What is the mechanism of action of metronidazole?
Metronidazole is a prodrug that undergoes intracellular reduction to produce reactive intermediates, which damage bacterial DNA and inhibit nucleic acid synthesis.
What precautionary advice should you give to a patient that is taking metronidazole?
Not to take alcohol for the next 48hours. Increase alcohol effects.
Which antibiotic class is commonly used to treat atypical bacterial infections such as Mycoplasma pneumoniae and Legionella pneumophila?
Macrolide antibiotics, such as azithromycin and clarithromycin, are commonly used to treat atypical bacterial infections.
And fluroquinolones.
What is the mechanism of action of azithromycin?
Azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing the translocation of the growing peptide chain.
Which antibiotic is commonly used as prophylaxis against bacterial endocarditis in individuals undergoing dental procedures?
Clindamycin/ Amoxicillin is commonly used as prophylaxis against bacterial endocarditis in individuals undergoing dental procedures.
What is the mechanism of action of amoxicillin?
Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing the cross-linking of peptidoglycan strands.
Which antibiotic class is commonly used to treat Clostridium difficile infections?
Metronidazole and vancomycin are commonly used to treat Clostridium difficile infections.
What is the mechanism of action of daptomycin?
Daptomycin disrupts bacterial cell membrane integrity by inserting into the bacterial membrane and causing depolarization and cell death.
Which antibiotic class is associated with the adverse effect of photosensitivity?
Tetracyclines are associated with the adverse effect of photosensitivity.
Anti-folate agents: sulphonamides and trimethoprim
What is the mechanism of action of linezolid?
Linezolid inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing the formation of the initiation complex.
Which antibiotic class is commonly used to treat Helicobacter pylori infections?
Proton pump inhibitors (PPIs), clarithromycin, and amoxicillin or metronidazole are commonly used to treat Helicobacter pylori infections.
What is the mechanism of action of nitrofurantoin?
Nitrofurantoin damages bacterial DNA and inhibits nucleic acid synthesis by forming reactive intermediates in the bacterial cell.
What antibiotics causes the urine to turn brown?
Nitrofurantoin
Which antibiotic class is commonly used to treat community-acquired pneumonia caused by Streptococcus pneumoniae?
Macrolide antibiotics, such as azithromycin and clarithromycin, are commonly used to treat community-acquired pneumonia caused by Streptococcus pneumoniae.
What is the mechanism of action of clindamycin?
Clindamycin inhibits bacterial protein synthesis by binding to the 50S and 23S ribosomal subunit and preventing peptide bond formation.
Which antibiotic class is commonly associated with the adverse effect of tendon rupture?
Fluoroquinolone antibiotics are commonly associated with the adverse effect of tendon rupture.
What is the mechanism of action of fosfomycin?
Fosfomycin inhibits bacterial cell wall synthesis by blocking the formation of peptidoglycan precursors.
Which antibiotic class is commonly used to treat infections caused by Pseudomonas aeruginosa?
Aminoglycosides, such as gentamicin and tobramycin, and antipseudomonal penicillins, such as piperacillin-tazobactam, are commonly used to treat infections caused by Pseudomonas aeruginosa.
What is the mechanism of action of colistin?
Colistin disrupts bacterial cell membrane integrity by binding to lipopolysaccharides in the outer membrane of gram-negative bacteria. (Polymyxin family)
Which antibiotic class is commonly used to treat skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA)?
Clindamycin and trimethoprim-sulfamethoxazole (TMP-SMX) are commonly used to treat skin and soft tissue infections caused by MRSA.
What is the mechanism of action of tigecycline?
Tigecycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit and preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.
Which antibiotic class is commonly used to treat infections caused by Enterococcus faecalis?
Ampicillin and vancomycin are commonly used to treat infections caused by Enterococcus faecalis.
What abx is contraindicated in CAP?
Daptomycin is contraindicated in CAP as it interacts with the pulmonary surfactant in the lungs.
What is the mechanism of action of chloramphenicol?
Chloramphenicol inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing the peptidyl transferase activity.
What classes of antibiotics are contraindicated in pregnancy?
Metronidazole, Chloramphenicol, Aminoglycosides, Tetracycline, Fluoroquinolones, Sulfonamides and Nitrofurantoin.
What is the mechanism of action of sulfamethoxazole?
Sulfamethoxazole inhibits bacterial folate synthesis by competing with para-aminobenzoic acid (PABA) for the active site of dihydropteroate synthase.
Which antibiotic class is commonly used to treat infections caused by Haemophilus influenzae?
β-lactam antibiotics, such as amoxicillin and ceftriaxone, are commonly used to treat infections caused by Haemophilus influenzae.
What is the mechanism of action of gentamicin?
Answer: Gentamicin inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit and causing misreading of the mRNA codon. (Aminoglycosides)
What is the mechanism of action of aztreonam?
Aztreonam inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing the cross-linking of peptidoglycan strands.
What are some antibiotics contraindicated in G6PD patients?
Nitrofurantoin & Sulfonamides
What is the mechanism of action of ceftriaxone?
Ceftriaxone inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing the cross-linking of peptidoglycan strands.
Which antibiotic class is commonly used to treat infections caused by methicillin-sensitive Staphylococcus aureus (MSSA)?
Penicillin and nafcillin are commonly used to treat infections caused by methicillin-sensitive Staphylococcus aureus (MSSA).
What is the primary use of ampicillin?
Ampicillin is primarily used to treat bacterial infections caused by susceptible organisms, including respiratory tract infections and urinary tract infections.