Quiz 2 - Antibiotics and Bacterial Infections

Cell Wall Synthesis

Examples:

• Penicillin

• Cephalosporins

• Vancomycin

• Bacitracin

Function:

• Prevent bacteria from forming their protective cell wall.

• Bacteria burst and die.

Remember:
No cell wall = bacteria dies.

Protein Synthesis

Targets:

• 30S ribosome

• 50S ribosome

30S Ribosome

Examples:

• Aminoglycosides

• Tetracyclines

50S Ribosome

Examples:

• Macrolides

• Chloramphenicol

• Clindamycin

• Linezolid

Function:

• Prevent bacteria from making proteins needed for growth.

Remember:
No proteins = bacteria cannot grow.

Cell Membrane

Examples:

• Polymyxin B

• Daptomycin

Function:

• Damage the bacterial cell membrane.

• Cell contents leak out.

• Bacteria die.

Remember:
Broken membrane = bacteria dies.

Nucleic Acid Synthesis

Examples:

• Fluoroquinolones

• Rifampicin

• Metronidazole

Function:

• Prevent bacteria from making DNA or RNA.

Remember:
No DNA/RNA = bacteria cannot reproduce.

Folic Acid Synthesis

Examples:

• Sulfonamides

• Trimethoprim

Function:

• Prevent bacteria from making folic acid needed for DNA synthesis.

Remember:
No folic acid = no DNA = no bacterial growth.

Examples:

• Penicillin

• Amoxicillin

• Ampicillin

• Cephalexin

• Ceftriaxone

• Carbapenems

Mechanism:

• Inhibit cell wall synthesis.

Beta-lactams

Example:

• Vancomycin

Mechanism:

• Cell wall synthesis inhibitor.

Used for:

• MRSA

Glycopeptides

Examples:

• Tetracycline

• Doxycycline

Mechanism:

• Protein synthesis inhibitor

• 30S ribosome

Important:

• Causes tooth discoloration in children.

• Avoid during pregnancy.

Aminoglycosides

Examples:

• Azithromycin

• Erythromycin

• Clarithromycin

Mechanism:

• Protein synthesis inhibitor

• 50S ribosome

Macrolides

Examples:

• Ciprofloxacin

• Levofloxacin

Mechanism:

• Inhibit DNA synthesis.

Common use:

• Urinary Tract Infection (UTI)

Fluoroquinolones

Mechanism:

• Inhibits RNA polymerase.

Rifampicin

Mechanism:

• Antimetabolite

• Inhibit folic acid synthesis.

Sulfonamides

Mechanism:

• Inhibits folic acid metabolism.

Often combined with:

• Sulfamethoxazole (Co-trimoxazole)

Trimethoprim

Cell membrane disruptor

Polymyxin B

Gram-Positive

• Purple

• Retains Crystal Violet

• Thick peptidoglycan layer

• No outer membrane

Gram-Negative

• Pink

• Takes Safranin stain

• Thin peptidoglycan layer

• Has outer membrane

Crystal Violet

Gram-positive

Safranin

Gram-negative

Drug of Choice:

Vancomycin

MRSA

Common antibiotic:

Ciprofloxacin

Urinary Tract Infection (UTI)

Macrolides

Fluoroquinolones

Beta-lactams

Pneumonia

BROAD-SPECTRUM ANTIBIOTICS

act against many different bacteria, including Gram-positive and Gram-negative organisms

NARROW-SPECTRUM ANTIBIOTICS

They target specific bacteria only.

ANTIBIOTIC RESISTANCE

Most common cause:

• Misuse and overuse of antibiotics.

Examples:

• Taking antibiotics for viral infections.

• Skipping doses.

• Stopping antibiotics early.

• Self-medication.