Indications for Culture and Antibiotic Sensitivity Testing

Indications for Culture and Antibiotic Sensitivity Testing

• Essential for patients with compromised immune systems (e.g., AIDS, leukemia)
• Crucial for rapidly progressive infections that require immediate attention
• Recommended when infections do not respond after 48 hours of treatment
• Important for managing recurrent infections
• Necessary for infections previously treated with multiple antibiotics

Routes of Administration

• Oral Route: Used for mild to moderate infections; available as syrup, suspension, tablets, or capsules
• Parenteral Administration (IV/IM): Essential for severe infections, ensures high serum concentrations; used when drugs are poorly absorbed gastrointestinally; supplied in ampules or vials

Antibiotic Resistance (AMR)

• Antimicrobial resistance occurs when bacteria can withstand antibiotic treatment, making standard therapies ineffective
• Contributes to persistent infections and increased mortality rates
• Misuse and overuse of antibiotics in healthcare significantly drive this issue
• Requires international cooperation across healthcare sectors to manage effectively

Adverse Effects of Antibiotics

• Common adverse effects include allergy and gastrointestinal issues
• Potential for antibiotic resistance develops with misuse
• Other effects: oral fungal infections, nephrotoxicity, tooth discoloration, vitamin B deficiency, and ototoxicity (hearing loss)

Terminology: Pharmacokinetics

• Pharmacokinetics deals with the drug's absorption, distribution, metabolism, and excretion within the body

Antibiotic Classification

• According to Source:

  • Natural: Penicillin, Erythromycin
  • Synthetic: Sulfonamides, Quinolones
  • Semisynthetic: Ampicillin, Amoxicillin

• According to Antimicrobial Spectrum:

  • Narrow-Spectrum: Effective against specific bacteria (e.g., gram-positive or gram-negative)
  • Broad-Spectrum: Effective against a wide range of species, useful for complex infections
  • Extended-Spectrum: Effective against gram-positive and some gram-negative bacteria; useful for multi-drug resistant infections

• According to Mode of Action:

  • Bacteriostatic Antibiotics: Inhibit bacterial growth, allowing the immune system to eliminate pathogens
  • Bactericidal Antibiotics: Directly kill bacteria, appropriate for severely ill patients

Mechanism of Action of Different Antibiotics

• Inhibition of Cell Wall Synthesis: Disrupts bacterial cell structure
• Inhibition of DNA Synthesis: Suppresses bacterial replication
• Inhibition of Ribosomal Protein Synthesis: Affects bacterial protein production
• Inhibition of Bacterial Metabolism: Interferes with metabolic processes essential for bacterial survival

Combination of Antibiotics

• Indications for Combination:

  • To broaden the antibiotic spectrum (e.g., Augmentin: Amoxicillin & Clavulanic acid)
  • To treat mixed bacterial infections like periodontitis
  • For managing serious infections such as meningitis
  • To combat resistant strains (e.g., tuberculosis, syphilis)
  • To minimize drug toxicity using lower doses of two drugs

• Results of Combinations:

  • Synergism: Combination of two bactericidal antibiotics results in a greater effect than if used alone (e.g., Penicillin + Aminoglycoside)
  • Addition: Combination of two bacteriostatic antibiotics produces an effect equal to their individual contributions (e.g., Tetracycline + Sulphonamide)

This quiz covers the essential scenarios where culture and antibiotic sensitivity testing is necessary, including for patients with compromised immune systems, severe infections, and more.