Lesson 16: Antimicrobial Therapy and Resistance Flashcards
(31 cards)
defined as that which minimizes the development of resistance as well as resulting in a therapeutically successful outcome.
antimicrobial therapy
Factors relevant to the Pathogenic Organism
✓ type
✓ number of organisms
✓ virulence
✓ pathogenic mechanism
✓ ability to acquire resistance to drug
✓ susceptibility to chemotherapy
Factors relevant to the infectious drug
✓ spectrum of activity
✓ route of administration
✓ dosage and frequency of administration
✓ duration of treatment
✓ distribution in body fluids
✓ direct drug toxicity
✓ effect on normal flora
✓ tissue residues
Factors relevant to the host
✓ species
✓ age
✓ immune status
✓ nutritional status
✓ nature and severity of infection
✓ site and duration of infection
✓ intercurrent infection
can be initiated as soon as specimens are collected and empirical chemotherapy can if necessary be modified when laboratory data are at hand
chemotherapy
depends on the susceptibility of the pathogen, pharmacokinetic characteristics of the drug, the amount of drug given at one time, the route, frequency of administration and the duration of treatment
effective antimicrobial therapy
others variables relating to chemotherapy;
✓ toxicity of the drug for the host
✓ half-life
✓ concentration and persistence at the site of infection
✓ effect on the normal flora of the host
antibiotic in food producing animals
chloramphenicol
Antimicrobial drugs can be classified in a number of ways, each of which has clinical importance. what are these?
✓ spectrum of activity against class of microorganisms
✓ antibacterial activity
✓ bacteriostatic or bactericidal
✓ pharmacodynamic activity
✓ mechanism of action
are narrow spectrum, because they inhibit only bacteria
penicillins
are broader because they inhibit both bacteria and protozoa
sulfonamides, trimethoprim, lincosamides
only inhibit fungi
polyenes
inhibit both gram positive and gram negative bacteria
tetracyclines
inhibit only gram positive
bacitracin and vancomycin
they inhibit only gram negative bacteria
polymyxin
are most active against gram-positive bacteria but will inhibit some gram-negatives
penicillin G or lincosamides
this distinction is an approximation that depends on drug concentrations and the organism involved.
bacteriostatic or bactericidal
bactericidal at high concentrations and bacteriostatic at lower ones
penicillin
antibacterial action is concentration or time dependent
pharmacodynamic activity
this is dependent on the drug class. this is probably the most useful of the classifications, since it determines the previous four classification approaches
mechanism of action
Four categories of Mechanism of Action of Antimicrobial Drugs
✓ inhibition of cell wall synthesis
✓ damage to cell membrane function
✓ inhibition of nucleic acid synthesis
✓ inhibition of protein synthesis
inhibition of cell wall synthesis example;
✓ penicillins and cephalosporins
✓ bacitracin and vancomycin
it inhibits cross-linkage between peptidoglycans in the cell wall, inhibiting division, and creating weak points during active growth and cell division
inhibition of cell wall synthesis
antibiotics that damage cell membrane function include the?
✓ polymyxins
✓ monensin
✓ antifungal polyenes
✓ imidazoles
