Antimicrobials Flashcards
What is an antibiotic?
A substance produced by a micro-organism that can inhibit the growth or kill other micro-organisms.
What is an antimicrobial?
A substance that can inhibit the growth or kill micro-organisms. It can be synthetic or made by other micro-organism.
What are the factors that determine the use of an antimicrobial?
Patient - age, circumstances, history of drug allergies
Drug - the side effects, spectrum of coverage, action - bactericidal or bacteriostatic, synergystic or antagonistic
Micro-organism - resistance & susceptibility to the antimicrobial
What are the main structural differences between a Gram Positive bacterium and a Gram Negative bacterium.
Gram positive - Thick peptidoglycan layer; No lipopolysaccharide
Gram negative - Thin peptidoglycan; has lipopolysaccharide
What substances form the peptidoglycan layer?
N-acetyl glucosamine and N-acetyl muramic acid
State 2 classes of anaerobes?
Clostridium, Bacteroides
What are the types of antimicrobial therapy?
- Targeted - based on selectivity and sensitivity test
- Empirical - treatment based on symptoms and epidemiological data
- Prophylactic - treatment done to prevent an infection
What are the differences between a narrow spectrum antibiotic and a broad spectrum antibiotic?
Narrow spectrum - kills a specific group of micro-organisms; less disturbances to the normal flora
Broad spectrum - kills a wide range of micro-organisms; has more significant disturbances to the normal flora
What is the main purpose of normal flora?
To protect the host by colonization resistance, preventing the growth of pathogens.
What are the differences between bactericidal antimicrobials and bacteriostatic antimicrobials?
Bactericidal - kills bacteria; inhibit the growth irreversibly; may lead to release of toxin and inflammatory response
Bacteriostatic - does not kill bacteria; inhibit the growth reversibly; allows the immune system to deal with the bacteria
Give an example for each of the following conditions:
Renal excretion
Enterohepatic circulation
Biliary excretion
Renal excretion - penicillin
Enterohepatic circulation - amoxicillin
Biliary excretion - naficillin, ceftriaxone
What are the 4 principles of pharmacokinetics?
Absorption
Metabolism
Distribution
Circulation
What antibiotics are closely associated with Clostridium difficile colitis?
Co-amoxiclav
Cephalosporin
Ciprofloxacin
Clindamycin
What are the 4 types of hypersensitivity?
- Type-1 : IgE mediated
- Type-2 : Antibody mediated
- Type-3 : Immune complexes associated
- Type-4 : Delayed - Cytotoxic T cells
What antibiotics interrupt the synthesis of cell wall?
Beta lactams
- Penicillins
- Cephalosporins
- Carbapenems
- Monobactam
Glycoproteins
- Teicoplanin
- Vancomycin
