Antibiotics Classification: Gram Positive vs Gram Negative
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Questions and Answers

What is the mechanism of action of all beta-lactams on bacterial cells?

Inhibit cross-linking of peptidoglycan, leading to autolysis and cell death

Which penicillin is administered intramuscularly?

  • Benzathine penicillin G (correct)
  • Penicillin V
  • Ampicillin
  • Penicillin G

    • Amoxicillin is commonly used for treating infectious endocarditis.

    False

    Carboxypenicillins, like Ticarcillin and Temocillin, are used to treat infections caused by Gram-negative ___________.

    <p>bacilli</p> Signup and view all the answers

    Match the following generations of cephalosporins with their respective activity:

    <p>First-Generation Cephalosporins = MSSA, N.meningitidis, B.anthracis Second-Generation Cephalosporins = MSSA, P.multocida, E.coli Third-Generation Cephalosporins = MSSA, N.gonorrhoeae, P.multocida Fourth-Generation Cephalosporins = MSSA, N.gonorrhoeae, M.catharralis Fifth-Generation Cephalosporins = MSSA/MRSA, N.meningitidis, S.pyogenes</p> Signup and view all the answers

    What is the mechanism of action of Glycopeptides?

    <p>inhibits cell wall synthesis</p> Signup and view all the answers

    Which of the following are adverse reactions associated with Glycopeptides? (Select all that apply)

    <p>Red man syndrome</p> Signup and view all the answers

    Fluoroquinolones have no activity on pneumococcus, making them suitable for respiratory infections.

    <p>False</p> Signup and view all the answers

    Tetracyclines inhibit bacterial protein synthesis by binding to the __________ ribosomal subunit.

    <p>30S</p> Signup and view all the answers

    Match the following antibiotics with their representatives:

    <p>Imipenem = Don’t use in CNS infections Ertapenem = No activity on P.aeruginosa Aztreonam = Inhalational administration in patients with cystic fibrosis Linezolid = Antibiotic of choice in MRSA pneumonia</p> Signup and view all the answers

    Which drug has advantages over macrolides including excellent bone diffusion and extended spectrum?

    <p>Clindamycin</p> Signup and view all the answers

    What is the mechanism of action of Fosfomycin?

    <p>Inhibits the synthesis of the bacterial wall</p> Signup and view all the answers

    Metronidazole inhibits bacterial DNA synthesis and is effective against _______ bacteria and protozoa.

    <p>Anaerobic</p> Signup and view all the answers

    Tigecycline has good tissue diffusion in alveolar macrophages, bone, muscle, and fatty tissue.

    <p>True</p> Signup and view all the answers

    Match the Aminoglycosides drug with the correct generation:

    <p>Streptomycin = First generation Gentamicin / Tobramycin = Second generation Amikacin = Third generation</p> Signup and view all the answers

    What is the mechanism of action of Colistin?

    <p>Binds to the negatively charged lipopolysaccharide molecules in the bacterial outer membrane and disrupts the normally tightly packed lipopolysaccharide molecules, leading to increased permeability and lysis of bacteria</p> Signup and view all the answers

    Study Notes

    Antibiotics Classification

    • Gram Positive vs Gram Negative: Key difference lies in the composition of bacterial cell walls.

    Beta-Lactams

    • Penicillins: Inhibit cross-linking of peptidoglycan in cell walls, leading to autolysis and cell death.
      • Penicillin G: Parenteral administration, 4-6 hour half-life.
      • Penicillin V: Oral administration, 6-8 hour half-life.
      • Benzathine Penicillin G: Intramuscular administration.
      • Indications: Streptococcal pharyngitis, scarlet fever, poststreptococcal reactive arthritis, syphilis, leptospirosis.
    • Antistaphylococcal Penicillins:
      • Methicillin (MSSA): Indications - skin infections, sepsis, endocarditis, osteoarthritis.
      • Oxacillin (MSSA): Indications - skin infections, sepsis, endocarditis, osteoarthritis.
      • Cloxacillin (MSSA): Indications - skin infections, sepsis, endocarditis, osteoarthritis.
      • Dicloxacillin (MSSA): Indications - skin infections, sepsis, endocarditis, osteoarthritis.
    • Aminopenicillins:
      • Ampicillin: Indications - pneumonia, L. monocytogenes infection, dental infections, infectious endocarditis.
      • Amoxicillin: Indications - pneumonia, L. monocytogenes infection, dental infections, infectious endocarditis.

    Beta-Lactamase Inhibitor Combinations

    • Mechanism of Action: Beta-lactamase inhibitors structurally resemble beta-lactams and bind to many beta-lactamases, rendering them unable to inactivate the co-administered beta-lactam.

    Cephalosporins

    • Generations:
      1. First-Generation Cephalosporins: Active against Gram-positive cocci, some Gram-negative bacilli.
      2. Second-Generation Cephalosporins: Active against anaerobic GNB, more resistant to beta-lactamases.
      3. Third-Generation Cephalosporins: Active especially on GNB, including non-fermentatives.
      4. Fourth-Generation Cephalosporins: Superior activity against streptococci, Ps. aeruginosa.
      5. Fifth-Generation Cephalosporins: Active against MRSA.
    • Adverse Effects: Allergic reactions, hematological reactions, neurological toxicity, Clostridium difficile colitis.

    Carbapenems

    • No activity against MRSA.
    • Active against: Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci, Gram-negative bacilli, anaerobic bacteria.
    • Indications: Severe localized or generalized infections with multidrug-resistant germs, nosocomial infections.
    • Adverse Effects: Allergic reactions, neurological toxicity, digestive disorders, hematological disorders.

    Monobactams

    • Active against: Gram-negative aerobic cocci and bacilli.
    • Indications: Severe aerobic GNB infections, especially in patients with beta-lactam allergy.
    • Aztreonam: Inhalational administration in patients with cystic fibrosis, secondary prophylaxis of Ps. aeruginosa infections.

    Glycopeptides

    • Mechanism of Action: Inhibition of cell wall synthesis.
    • Time-dependent antimicrobials.
    • Active against: Gram-positive bacteria, including MRSA.
    • Indications: Severe infections due to streptococci, enterococci, pneumococci, MRSA/MSSA in patients allergic to beta-lactams.
    • Adverse Effects: Red man syndrome, nephrotoxicity, ototoxicity, cytopenias, hypersensitivity reactions.

    Oxazolidinones

    • Mechanism of Action: Inhibition of protein synthesis.
    • Active against: Gram-positive bacteria, including MRSA, VRE.
    • Indications: Systemic infections with vanco-R, methi-R, or vanco-S staphylococci/enterococci.
    • Adverse Effects: Digestive disorders, myelosuppression, peripheral neuropathy, lactic acidosis.

    Macrolides

    • Mechanism of Action: Inhibition of bacterial protein synthesis.
    • Active against: Gram-positive cocci, some Gram-negative bacilli, atypical bacteria, mycobacteria.
    • Indications: Mild to moderate URT and LRT infections, Legionnaire's disease, diphtheria, pertussis, atypical mycobacteriosis.
    • Adverse Effects: Digestive disorders, allergic reactions, hepatotoxicity, reversible ototoxicity.

    Tetracyclines

    • Mechanism of Action: Inhibition of bacterial protein synthesis.
    • Active against: Gram-positive and Gram-negative bacteria, some anaerobic bacteria, rickettsiae, chlamydiae, mycoplasma.
    • Indications: Community-acquired pneumonia, M. catarrhalis infections, brucellosis, Legionnaire's disease.### Brucellosis
    • Brucellosis is caused by bacteria of the genus Brucella.
    • The treatment of brucellosis involves the use of tetracyclines, such as doxycycline, and rifampicin.

    Tetracyclines

    • Tetracyclines are a class of antibiotics that inhibit protein synthesis by binding to the 30S ribosomal subunit.
    • Side effects of tetracyclines include:
      • Skin manifestations: photosensitization, morbilliform eruptions, urticaria
      • Digestive disorders: nausea, vomiting, abdominal pain
      • Dental and bone abnormalities: yellow-brown deposits and staining of the teeth, tooth enamel hypoplasia
      • Contraindications: pregnancy, breast-feeding, children under 8 years old
      • Nephrotoxicity, neurotoxicity, hepatotoxicity, hematological disorders

    Fluoroquinolones

    • Fluoroquinolones are a class of antibiotics that inhibit bacterial DNA synthesis by acting on DNA gyrase and topoisomerase IV enzymes.
    • They have good oral bioavailability and tissue diffusion in the respiratory tract, kidney, liver, bile, muscle, prostate, skin, and bone.
    • Representatives of fluoroquinolones include:
      • "Old" FQ (urinary): norfloxacin, ciprofloxacin
      • "New" FQ (respiratory): levofloxacin, moxifloxacin
    • Spectrum of fluoroquinolones:
      • Respiratory FQ: S. pneumoniae, Neisseria spp., M. catharralis, M. tuberculosis, Legionella spp.
      • Others: Enterobacteriaceae, Pseudomonas aeruginosa, Mycobacterium spp., Atypical bacteria (Mycoplasma spp., Chlamydia spp., Coxiella spp.)
    • Side effects of fluoroquinolones:
      • C. difficile infection, digestive disorders, osteo-muscular disorders, hepatic disorders, cardiac disorders, cutaneous disorders, neurological disorders, renal disorders, hematological disorders

    Lincosamides

    • Clindamycin is a lincosamide that has excellent bone diffusion and an extended spectrum compared to macrolides.
    • Indications of clindamycin:
      • Osteoarticular infections
      • Skin and soft tissue infections
      • Aspiration pneumonia
      • Infections with anaerobes (except Bacteroides)
      • Cerebral toxoplasmosis
      • Can replace penicillin in allergic patients

    Fosfomycin

    • Fosfomycin is a antibiotic that inhibits the synthesis of the bacterial wall.
    • Forms of fosfomycin: fosfomycin trometamol (PO), fosfomycin sodium (IV)
    • Activity spectrum: GPC, GNB (no activity against Acinetobacter, anaerobes)
    • Indications:
      • Acute cystitis
      • Asymptomatic bacteriuria in pregnant women
    • Side effects:
      • None mentioned

    Nitrofurantoin

    • Nitrofurantoin is an antibiotic that alters proteins, nucleic acids, and bacterial lipids.
    • Spectrum: GPC, Proteus spp., E. coli
    • Indications:
      • Treatment of asymptomatic bacteriuria
      • Uncomplicated/complicated low UTIs
      • Chemoprophylaxis before transurethral interventions

    Metronidazole

    • Metronidazole is an antibiotic that inhibits bacterial DNA synthesis.
    • Spectrum: anaerobic bacteria, protozoa (Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica)
    • Adverse effects:
      • Digestive disorders, metallic taste
      • Neurological disorders: reversible peripheral neuropathy
      • Mutagenic and carcinogenic potential
      • Turns urine red
      • Interactions: disulfiram (+alcohol) effect, anti-vitamin K effect

    Tigecycline

    • Tigecycline is a antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.
    • Good tissue diffusion in alveolar macrophages, bone, muscle, fatty tissue, etc.
    • Spectrum:
      • Streptococci, pneumococci PS,PR
      • Staphylococci MS, MR
      • Resistant enterococci
      • C. difficile
      • Enterobacteriaceae, MDR/XDR
    • Indications:
      • Intra-abdominal infections of unspecified etiology
      • Severe soft tissue infections
      • "Salvage" treatment in complicated C. difficile infections
    • Side effects:
      • Digestive: nausea, vomiting, acute pancreatitis
      • Photosensitivity
      • Hepatic cytolysis syndrome

    Aminoglycosides

    • Aminoglycosides are a class of antibiotics that inhibit bacterial protein synthesis.
    • Representatives of aminoglycosides:
      • First generation: streptomycin
      • Second generation: gentamicin, tobramycin
      • Third generation: amikacin
    • Spectrum of aminoglycosides:
      • GPC, GNC, GPB
      • M. tuberculosis, Brucella spp., Yersinia spp., Francisella tularensis
    • Indications:
      • Infective endocarditis
      • Localized/generalized staphylococcal infections
      • High urinary tract infections
      • Severe listeria infections
      • Tuberculosis with MDR strains
    • Side effects:
      • Nephrotoxicity, ototoxicity, vestibular toxicity
      • Rapidly reversible neuromuscular blockage after iv administration of calcium gluconate
      • Allergic reactions
      • Drug interactions

    Colistin (Polymyxins)

    • Colistin is a antibiotic that binds to the negatively charged lipopolysaccharide molecules in the bacterial outer membrane and disrupts the normally tightly packed lipopolysaccharide molecules, leading to increased permeability and lysis of bacteria.
    • Spectrum: aerobic Gram-negative bacteria (including P. aeruginosa)
    • Indications:
      • Severe localized or generalized infections with multidrug-resistant germs
      • Especially nosocomial infections
    • Side effects:
      • Nephrotoxicity
      • Neurotoxicity
      • Remember to monitor the creatinine and urea levels!

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    Description

    This quiz covers the classification of antibiotics, specifically Gram positive and Gram negative bacteria, and the mechanism of action of beta-lactams and penicillins.

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