Anti-Infective Agents Overview

Anti-Infective Agents

• Drugs that treat and prevent infections from microorganisms like bacteria, viruses, fungi, and parasites
• Target foreign organisms' survival mechanisms to protect human cells
• Support the immune system to recover from infections
• Essential for treating and preventing the spread of infectious diseases

Types of Anti-Infective Therapy

• Antibiotics: Kill or inhibit bacteria
• Antifungals: Disrupt fungal growth
• Antivirals: Interfere with virus replication
• Anti-protozoans: Treat protozoan infections
• Anti-helmintics: Treat worm infections
• Anti-neoplastics: Target cancer-causing microorganisms

Mechanism of Action (MOA)

• Targeting Invaders: Disrupt functions of invading organisms to prevent reproduction and cause cell death
• Disrupting Normal Function: Interfere with pathogen activities without harming host cells
• Selective Toxicity: Specifically affect pathogen cells only

Anti-Infective Activity

• Narrow-Spectrum: Effective against a limited range of specific microorganisms
• Broad-Spectrum: Effective against a wide variety of microorganisms

Microorganisms Develop Resistance

• Enzyme Deactivation: Bacteria produce enzymes that deactivate antibiotics
• Altering Cell Permeability: Changes prevent drug entry into cells
• Modifying Binding Sites: Alters drug targets to block action
• Producing Antagonists: Microorganisms produce chemicals that neutralize drug effects

Preventing Resistance

• Proper Dosage: Doses must eradicate resistant microorganisms
• Combating Resistance: Maintain appropriate dosages and treatment durations
• Patient Compliance: Adherence to full treatment is critical

Usage Guidelines

• Prescribe Appropriately: Use anti-infectives only for specific infections
• Cautious Usage: Avoid indiscriminate use to prevent resistance
• Follow Guidelines: Adhere to established protocols for responsible use

Treatment of Systemic Infections

• Identification of the Pathogen: Culture samples to determine microorganisms causing infection
• Sensitivity of the Pathogen: Testing to find effective drugs
• Combination Therapy: Using multiple drugs to enhance effectiveness and reduce side effects

Combination Therapy: Additional Benefits

• Synergistic Effects: Increased efficacy with combined drugs
• Delayed Resistance: Preserves effectiveness of anti-infectives
• Broader Spectrum: Addresses polymicrobial infections comprehensively

Adverse Reactions to Anti-Infective Therapy

• Kidney Damage: Common with drugs metabolized by the kidneys; hydration prevents accumulation
• Gastrointestinal Toxicity: Side effects include nausea and diarrhea
• Neurotoxicity: Affects cranial nerve VIII, causing dizziness and hearing loss
• Hypersensitivity Reactions: Immune responses can lead to severe reactions
• Superinfections: Disruption of normal flora can allow opportunistic infections

Prophylaxis

• Travel Prophylaxis: Preventive measures for infections in endemic areas
• Surgical Prophylaxis: Antibiotics to prevent post-operative infections
• Cardiac Conditions: Prophylaxis for those at risk of bacterial endocarditis

Antibiotics/Antibacterial

• Bacteriostatic Drugs: Inhibit bacterial growth
• Bactericidal Drugs: Kill bacteria directly

Goal of Antibiotic Therapy

• Decrease Bacterial Population: Reduce bacteria for immune system management
• Support Immune System: Assist in eliminating remaining pathogens
• Prevent Complications: Effective treatment prevents infection worsening

Bacterial Classification

• Gram-Positive Bacteria: Retain stain; associated with respiratory infections
• Gram-Negative Bacteria: Lose stain; often resistant and linked to GI and urinary infections

Aminoglycosides

• Powerful antibiotics that treat serious infections from gram-negative bacteria
• Indications: For severe infections like pneumonia and sepsis
• Examples: Amikacin, Gentamicin, Kanamycin, Neomycin, Streptomycin, Tobramycin

Cephalosporins

• MOA: Bactericidal; disrupt cell wall synthesis
• Generations:
  • First-Generation: Effective against gram-positive and some gram-negative (e.g., E.coli) - Examples: Cefadroxil, Cefazolin, Cephalexin
  • Second-Generation: Broader activity including H.influenzae - Examples: Cefaclor, Cefuroxime, Cefprozil
  • Third-Generation: More potent against gram-negative; weaker against gram-positive - Examples: Cefdinir, Ceftriaxone, Ceftazidime
  • Fourth-Generation: Active against resistant strains - Examples: Cefepime, Cefditoren
• Adverse Reactions: Disulfiram-like reactions with alcohol

Fluoroquinolones

• Broad Spectrum: Effective against various bacteria
• MOA: Inhibit bacterial DNA enzymes
• Indications: For infections like UTIs and respiratory infections
• Examples: Ciprofloxacin, Levofloxacin, Gemifloxacin

Macrolides

• MOA: Inhibit protein synthesis in bacteria
• Indications: Effective against respiratory and STIs
• Examples: Erythromycin, Azithromycin, Clarithromycin

Tetracyclines

• MOA: Inhibit protein synthesis
• Indications: Effective for rickettsiae and acne
• Examples: Tetracycline, Doxycycline, Minocycline

Antituberculosis Drugs

• First-Line Drugs: Isoniazid (INH), Rifampin, Ethambutol, Pyrazinamide
• Second-Line Drugs: Ethambutol, Pyrazinamide
• Third-Line Drugs: Capreomycin, Cycloserine
• Major Side Effects: Rifampicin: Causes red-orange secretions; Isoniazid: Peripheral neuritis; Pyrazinamide: Increases uric acid; Ethambutol: Can cause visual problems

Leprostatic Drugs

• Dapsone: Main treatment for leprosy; emerging resistant strains

Monobactam Antibiotics

• Aztreonam: Effective against gram-negative bacteria
• Indications: Treat UTIs, skin infections, and intra-abdominal infections

Carbapenems

• Class Overview: Broad-spectrum antibiotics effective against many resistant bacteria
• Examples: Imipenem, Meropenem, Ertapenem, Doripenem

This quiz provides an overview of anti-infective agents used to treat and prevent infections caused by various microorganisms including bacteria, viruses, fungi, and parasites. It covers the types of anti-infective therapies, their mechanisms of action, and their importance in supporting the immune system and managing infectious diseases.