Antimicrobial Therapy Flashcards
(57 cards)
Antimicrobial agent vs Antimicrobial drug
An antimicrobial is an agent that kills all microorganisms (i.e. fungi, bacteria etc) or stops their growth.
Antibiotic- A drug used to treat bacterial infections.
Antimicrobial agent
- suppress growth and multiplication
- kill organism
Natural Antibiotic - drug
Penicillin derived from fungi
Antibiotics can also be derived from other bacteria e.g. aminoglycosides and carbapenems
Bacillus polymyxa– Polymixin, Penicillium notatum– Penicillin
-Cephalosporium acremonium–> Cephalosporin
-Streptomyces venezuelae–> Chloramphenicol
Semi Synthetic
ampicillin, amoxicillin, methicillin
Synthetic
Sulphonamides, Quinolones
Selective Toxicity
Cause greater harm to microorganisms than to host
Chemotherapeutic index = lowest dose toxic to patient divided by dose typically used for therapy
-it selectively kills or inhibits the growth of microbial targets while causing minimal damage to host.
Classification - range of activity
Narrow spectrum - active towards fewer m.o.s (macrolides, polymyxin)
Narrow broad spectrum - active towards gram +ve and gram -ve (beta lactam)
Moderate spectrum - active towards Gram +ve bacteria and some systemic and UTI causing
Gram -ve bacteria. (Aminoglycosides, Sulfonamide)
Broad spectrum - active against Gram +ve and Gram -ve except Pseudomonas and Mycobacteria (Chloramphenicol, Tetracycline)
Anti-mycobacterial antibiotics: Ethambutol, Rifampicin, Isoniazid, Pyrazinamide-Treats TB
Broad spectrum is good first treatment of infection (T/F)
False; Can cause resistance to bacteria or destroy normal flora
Bacteriostatic vs Bactericidal
Bacteriostatic: Antibiotics that stops or inhibits the growth of bacteria i.e. no bacteria multiplication or
generation of new bacteria but they do not kill bacteria e.g. tetracycline, chloramphenicol – slow acting
• Bactericidal: Antibiotics that actually kill bacteria by any mechanism depending on the antibiotic used,
e.g. aminoglycosides – fast acting via killing
Lag, log, stationary, death phases
Lag+log phase - organism is maximally multiplying
Stationary - no deaths no new bacteria
Death- of bacteria
What phase do antimicrobials work at?
Log phase
Synergistic - Drug combinations
Action of one drug enhances the activity of another
Antagonistic - Drug combinations
Activity of one drug interferes with the action of another
Additive - Drug combinations
Neither synergistic or antagonistic
Indifference - Drug combinations
Each drug works no better or no worse alone or in combination
Prophylaxis therapy
– no organisms identified but used as a precautionary measure (used for prevention of infection)
Empirical therapy
– initial – infecting organism not identified – single broad spectrum agent (treat until you know what you are treating)
Definitive therapy
– microorganism identified – a narrow –spectrum low toxicity regiment to complete the course of treatment (definite diagnosis)
PK vs PD
Pharmacokinetics (PK) refers to the movement of drugs through the body, whereas pharmacodynamics (what body does to drug)
(PD) refers to the body’s biological response to drugs. (what drug does to body)
By graphing drug concentration versus time, you can get some ballpark estimates of the drug’s basic PK properties (T/F)
True
The maximum concentration the drug attains
Cmax
Time at which this maximum occurs
Tmax
Classification of Antimicrobial Agents against organisms
Antibacterial •Antiviral •Antifungal •Antiprotozoan •Anthelmintic
β lactam antibiotics: chemical composition classification
Penicillin, cephalosporin, carbapenem, monbactam - -Beta lactam rings present with side chains
