Short Revision Summary Flashcards
What is selective toxicity?
Selective toxicity refers to the ability of a drug to target and kill microorganisms or pathogens without causing significant harm to the host cells. This is achieved by targeting specific features of the pathogen that are absent or significantly different in host cells, such as bacterial cell walls or enzymes.
What are the various methods for identifying bacteria causing an infection?
Methods for bacterial identification include:
Gram stain: Differentiates bacteria based on cell wall structure (Gram-positive or Gram-negative).
Culture: Growing bacteria on specific media to isolate and identify them.
Biochemical tests: Identifying bacteria based on metabolic characteristics.
Molecular methods: PCR and gene sequencing for identification based on genetic material.
Serological tests: Detecting bacterial antigens or antibodies against the bacteria.
What are MIC and MBC, how are they calculated, and why do they matter?
MIC (Minimum Inhibitory Concentration): The lowest concentration of an antimicrobial that prevents visible growth of a microorganism.
MBC (Minimum Bactericidal Concentration): The lowest concentration that kills the bacteria, usually determined by subculturing from an MIC test.
Both are determined through dilution methods in broth or agar plates. MIC and MBC help determine the appropriate drug dose and efficacy in treating infections.
What patient factors need to be considered when choosing an appropriate antimicrobial drug?
Factors to consider include:
Age: Age-related differences in pharmacokinetics and drug tolerance.
Kidney and liver function: Impacts drug metabolism and excretion.
Pregnancy and lactation: Safety for the fetus or infant.
Allergies and previous adverse reactions: Risk of allergic reactions or side effects.
Comorbidities: Underlying health conditions that might affect drug choice or efficacy.
Immune status: In immunocompromised patients, infections may be harder to treat.
What are the various drug interactions that can occur in antimicrobial therapy?
Common drug interactions include:
Synergism: Two drugs working together to enhance each other’s effects.
Antagonism: One drug reduces the effectiveness of the other.
Enzyme inhibition/induction: One drug can affect the metabolism of another, altering its concentration in the body.
Displacement from protein binding: One drug can displace another from plasma proteins, increasing free drug concentration.
Additive effects: Two drugs have similar effects, leading to increased efficacy or toxicity.
What is “antibiotic spectrum”?
Antibiotic spectrum refers to the range of bacteria that an antibiotic can effectively target.
Narrow-spectrum antibiotics target specific types of bacteria.
Broad-spectrum antibiotics target a wide range of bacteria, including both Gram-positive and Gram-negative.
What are the pharmacokinetics of antimicrobial drugs?
The pharmacokinetics of antimicrobial drugs include:
Absorption: How the drug is absorbed into the bloodstream (oral, intravenous, etc.).
Distribution: How the drug is distributed throughout the body (tissues, fluids).
Metabolism: How the body processes and breaks down the drug (primarily in the liver).
Excretion: How the drug is eliminated from the body (usually through the kidneys or liver).
Pharmacokinetics influence the drug’s effectiveness, dosage, and frequency of administration.
What are the main reasons for the emergence and re-emergence of tuberculosis?
HIV/AIDS epidemic: Weakened immune systems make individuals more susceptible to TB.
Poverty and overcrowding: Poor living conditions facilitate the spread of TB.
Malnutrition: Weakens the immune system and makes individuals more vulnerable.
Drug resistance: Improper use of antibiotics leads to the development of drug-resistant strains.
Increased travel and migration: Can spread TB to new areas.
What are the challenges associated with diagnosing tuberculosis?
Slow growth of Mycobacterium tuberculosis: Takes weeks to culture.
Non-specific symptoms: Fever, cough, weight loss can be mistaken for other illnesses.
Difficulty in obtaining sputum samples: Especially in children and immunocompromised individuals.
What are the challenges associated with treating tuberculosis?
Long treatment duration: Requires multiple drugs for 6-9 months.
Adverse effects of drugs: Can cause liver damage, kidney problems, and neurological side effects.
Drug resistance: Makes treatment more difficult and less effective.
Non-adherence to treatment: Can lead to treatment failure and the spread of drug-resistant TB.
What are the pharmacological strategies for treating tuberculosis?
First-line drugs: Isoniazid, rifampicin, pyrazinamide, ethambutol.
Second-line drugs: Used for drug-resistant TB, including fluoroquinolones and aminoglycosides.
What are the non-pharmacological strategies for preventing and controlling tuberculosis?
Early diagnosis and treatment: To prevent the spread of the disease.
Contact tracing and preventive therapy: To identify and treat individuals exposed to TB.
Improved living conditions: Reducing overcrowding and improving ventilation.
Vaccination: BCG vaccine offers some protection against severe forms of TB, especially in children.
Public health measures: Education, screening, and infection control in healthcare settings.
How is the complement system activated?
The complement system can be activated through three pathways: the classical pathway, the alternative pathway, and the lectin pathway.
How does the classical pathway activate the complement system?
Antibodies bind to antigens on the surface of pathogens, which activates the complement system.
How does the alternative pathway activate the complement system?
Pathogen surfaces directly activate the complement system.
