Antibiotics Classifications and Functions

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Questions and Answers

Which type of antibiotics primarily targets gram-negative organisms and is effective against Pseudomonas?

Macrolides

β-lactams

Aminoglycosides (correct)

Tetracyclines

What is the primary mechanism of action of macrolides like erythromycin, clarithromycin, and azithromycin?

Inhibit protein synthesis (correct)

Inhibit folate synthesis

Disrupt nucleic acid synthesis

Inhibit cell wall synthesis

Which antibiotic class has a synergistic action when combined with β-lactams?

Macrolides

Aminoglycosides (correct)

Lincosamides

Glycopeptides

Which of the following macrolides is NOT typically used in clinical practice?

Vancomycin Signup and view all the answers

Which statement about macrolides is false?

They are effective only against gram-positive bacteria. Signup and view all the answers

Which antibiotic is considered the first choice for patients who are allergic to penicillins?

Erythromycin Signup and view all the answers

What advantage does clarithromycin have over erythromycin in treating certain infections?

Higher activity against H. pylori Signup and view all the answers

Which of the following is NOT typically a first-line treatment for individuals allergic to penicillins?

Amoxicillin Signup and view all the answers

In which scenario would erythromycin primarily be used?

For patients with a known penicillin allergy Signup and view all the answers

Which feature is a distinguishing factor of clarithromycin compared to erythromycin?

It has a stronger effect against H. pylori. Signup and view all the answers

What is a key characteristic of broad-spectrum antibiotics?

They are effective against a wide variety of microbial species. Signup and view all the answers

Which statement accurately describes extended-spectrum antibiotics?

They cover a broad range of gram-positive and significant gram-negative bacteria. Signup and view all the answers

Which of the following penicillins is classified as an antistaphylococcal penicillin?

Methicillin Signup and view all the answers

Which of the following options best describes the spectrum of Benzyle Penicillins?

Narrow spectrum primarily targeting Gram-positive bacteria Signup and view all the answers

Which of the following best differentiates extended-spectrum antibiotics from broad-spectrum antibiotics?

Extended-spectrum antibiotics are modified for a broader action, to include more gram-positive and several gram-negative bacteria. Signup and view all the answers

Which of the following penicillins is NOT considered an extended-spectrum penicillin?

Cloxacillin Signup and view all the answers

The term 'broad-spectrum' implies an antibiotic's effectiveness against which of the following?

A wide variety of microbial species. Signup and view all the answers

Which of the following statements is false regarding the types of antibiotics?

Extended-spectrum antibiotics are specifically modified for gram-positive bacteria. Signup and view all the answers

What characteristic defines antistaphylococcal penicillins like Methicillin and Cloxacillin?

They are resistant to penicillinase-producing bacteria Signup and view all the answers

Which of the following best describes the relationship between extended-spectrum penicillins and narrow-spectrum penicillins?

Extended-spectrum penicillins have a broader range of activity than narrow-spectrum penicillins Signup and view all the answers

Study Notes

Antibacterial Classification

Three main classes of antibiotics based on their mechanisms of action:
- Inhibiting cell wall synthesis
- Inhibiting protein synthesis
- Inhibiting nucleic acid synthesis

Bacteriostatic vs Bactericidal

Bacteriostatic antibiotics prevent bacterial growth
Bactericidal antibiotics kill bacteria

Antibiotic Spectrum

Narrow-spectrum antibiotics target a specific group of microorganisms
Extended-spectrum antibiotics are effective against a wider range of gram-positive and gram-negative bacteria
Broad-spectrum antibiotics affect a large variety of microbial species

Beta-Lactams (Penicillins)

Mechanism of Action: Cell wall inhibitors
- Bactericidal
Natural Penicillins: Narrow spectrum
Extended-Spectrum Penicillins: Wider spectrum
Clinical Uses:
- Streptococcal infections
- Salmonella infections
- Spirochetes infections (syphilis, gonorrhea)
- Staphylococcal infections
- Rheumatic Fever
- Prophylaxis in congenital heart disease
Adverse Effects:
- Type I hypersensitivity reaction
- Diarrhoea
Beta-Lactamase Inhibitors:
- Combined with penicillins to protect them from enzymatic breakdown
- Extend the antimicrobial spectrum

Cephalosporins

Clinical Uses:
- Meningitis (3rd and 4th generation)
Adverse Effects:
- Similar to penicillins
Cross-Sensitivity:
- Some patients allergic to penicillins may also be allergic to cephalosporins (5-10% cross-reactivity)

Inhibitors of Protein Synthesis

Tetracyclines: bacteriostatic, broad-spectrum, used for various infections
- Adverse effects: teeth discoloration, hepatotoxicity, phototoxicity
Aminoglycosides: (gentamicin, tobramycin) bactericidal; mainly effective against gram-negative bacteria, oxygen dependent, ineffective against anaerobes
- Adverse effects: damage to the kidneys
Macrolides: (erythromycin, clarithromycin, azithromycin) bacteriostatic; wider spectrum; erythromycin preferred for penicillin allergy; clarithromycin and azithromycin used for H. pylori and Legionellosis, respectively.
- Adverse effects: nausea, vomiting, abdominal pain
Chloramphenicol: broad-spectrum; bacteriostatic -Adverse effects: blood disorders and gray baby syndrome in newborns

Inhibitors of Nucleic Acid Synthesis

Quinolones: inhibit DNA gyrase; broad spectrum; used in UTI, respiratory infections, traveler's diarrhea
- Adverse effects: tendon rupture, CNS symptoms, phototoxicity.
Sulfonamides and Trimethoprim: inhibit folate synthesis, bacteriostatic; used in UTIs, infections, and other infections
- Adverse Effects: crystalluria, nephropathy, hypersensitivity reactions, bone marrow depression
Co-trimoxazole: combination of sulfamethoxazole and trimethoprim
- More potent
- Synergistic combination, wider spectrum
- Used in tuberculosis

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Description

This quiz covers the classification of antibiotics based on their mechanisms of action, including bacteriostatic and bactericidal properties. It also examines the spectrum of antibiotics and the unique features of beta-lactams. Test your knowledge on how these critical medications function against bacteria.