12.Rational use of antibiotics.pptx prophylactic

12.Rational use of antibiotics.pptx prophylactic

1. Rational use of antibiotics Yonas Ademe Oct, 2017 1

2. Definition Rational use of antibiotics is administration of: T he right drug F or the right microorganism At the right dose Through the appropriate route For the appropriate duration 2

3. Why rational use of antibiotics? Drug resistance Wastage Cost Side effects 3

4. Principles of rational use of antibiotics Select an agent (or agents) that will have efficacy against likely organisms Initial antimicrobial selection being broad, with a later narrowing of agents based on patient response and culture results Sets the duration of antibiotic therapy from the outset Curtail antibiotic administration when clinical and microbiologic evidence does not support the presence of an infection Limits therapy to a short course in every possible instance Discontinue antibiotics after an appropriate course of therapy 4

5. Indications for antibiotics For prevention of infection Prophylactic antibiotics For treatment of infection Emperic antibiotics A ntibiotics for a diagnosed i nfection but before established antibiotics sensitivity Definitive antibiotics A ntibiotics for a diagnosed infection with known antibioti c s sensitivity 5

6. Basic principles of prophylactic antibiotics Single dose (not more than 24 hrs) Maximum serum level at the time of incision Targeted to the microbial flora around the site of surgery 6

7. Mechanism of action of antibiotics Inhibition of cell wall synthesis B-lactam antibiotics Inhibition of cell membrane function Polymyxin B Inhibition of protein synthesis Aminoglycosides, macrolides, TTC , CAF Inhibition of nucleic acid synthesis Quinolones, m etronidazoles , r ifampin Inhibition of Bacterial metabolism Sulfonamides, t rimethoprim Bacteriostatic Vs. Bactericidal 7

8. Properties of an ideal antibiotic Able to stand the acidic environment of the stomach C apable of being absorbed by the small intestine Soluble in body fluids Slowly metabolized Selective toxicity Free of inducing hypersensitivity (allergic) reaction Exerting no significant effect on the resident micro flora of the host Strong enough to withstand microbial resistance Relatively inexpensive 8

9. Choice of antibiotics Factors Microbial factors Identification of the infecting organism Gram’s stain and/or culture Determination of antimicrobial susceptibility of infecting organism S ensitivit y Antibiotics related Spectrum of action Route of administration Side effects Site of infection Host factors Age (organ function) Physiological condition (like pregnancy) Co-morbid condition 9

10. Antibiotic Resistance Broadly divided into 2 forms I ntrinsic resistance , in which a specific species is inherently resistant to a specific antibiotic (e.g., GNB resistant to vancomycin ) A cquired resistance , in which a change in the genetic composition of the bacteria occurs It can be the result of intrinsic changes within the native genetic material of the pathogen or can be transferred from another species ( by mobile genetic elements - plasmids ) 10

11. Cont. The molecular mechanisms by which bacteria acquire resistance to antibiotics can be broadly classified into 4 categories Neutralization by inactivating enzymes Decreased intracellular concentration of antibiotic, either by decreased influx or increased efflux Alteration of the target at which the antibiotic will act Complete elimination of the target at which the antibiotic will act Bind up of antibiotics 11

12. Measures to limit d rug r esistance Maintaining sufficiently high levels of the drug in tissues T o inhibit both the original population and first-step mutants Simultaneously administering two drugs that do not give cross-resistance Each of which delays the emergence of mutants resistant to the other drug A voiding exposure of microorganisms to a particularly valuable drug by limiting its use 12

13. Why do patients on antibiotics fail to improve? Inadequate source control The initial operative procedure was not adequate The initial procedure was adequate but a complication has occurred Super-infection A super-infection has developed at a new site Failure of antibiotics The drug choice is correct, but not enough is being given (dose) Another or a different drug is needed (type) Wrong route of administration (route) 13

14. Combination antibiotics Synergism /additive action To prevent emergence of resistance In polymicrobial infections 14

15. End! 15