Surgical infections and antibiotics selections


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Surgical infections and antibiotics selections

  1. 1. Surgical Infections and Antibiotic Selection By: Masoud Salaran DVM, Resident in Veterinary Surgery
  2. 2. Introduction Antibiotic golden age 1941 Prophylactic therapeutic
  3. 3. Bacterial survival in a host depends on: bacterial virulence and numbers host immunocompetence wound factors that deactivate host defenses presence of blood clots foreign material ischemic tissue pockets of fluid
  4. 4. MECHANISMS OF ANTIBIOTIC ACTION  Destruction of Bacterial Cell Walls  Inhibition of Protein Synthesis  Inhibition of DNA Synthesis
  5. 5. Destruction of Bacterial Cell Walls β-lactam ring antibiotics Penicillins Vancomycin Cephalosporins Bacitracin Carbapenems Polymyxin Monobactams Nystatin Amphotericin B Imidazoles
  6. 6. Aminopenicillins amoxicillin, ampicillin Gram and Gram aerobes and some Gram Carboxypenicillins better Gram ticarcillin and anaerobe spectrums than the aminopenicillins Ureidopenicillins best Gram anaerobes piperacillin, mezlocillin spectrums of all the penicillins
  7. 7. Cephalosporins
  8. 8. Inhibition of Protein Synthesis Bind to bacterial ribosomes, causing reversible inhibition of protein synthesis  Chloramphenicol  Tetracycline  Erythromycin  Clindamycin
  9. 9. Inhibition of Protein Synthesis Chloramphenicol: Broad-spectrum activity against streptococci, staphylococci, Salmonella spp., Brucella spp., Pasteurella spp., Ehrlichia spp., Rickettsia spp., and anaerobes, but it has poor activity against Pseudomonas spp. Highly lipophilic
  10. 10. Tetracyclines Tetracycline, Oxytetracycline, Doxycycline, Minocycline Many Gram and Gram bacteria, including Chlamydia spp., Rickettsiae, Spirochetes, Mycoplasma spp., Bacterial L-forms, and some Protozoa Doxycycline fewer side effects Staphylococci, Enterococci, Pseudomonas spp., and Enterobacteriaceae
  11. 11. Erythromycin Readily absorbed Narrow spectrum New derivatives  Clarithromycin Azithromycin Dirithromycin Azithromycin Aerobic bacteria (e.g., Staphylococci, Streptococci, Helicobacter spp.) and anaerobes. Mycoplasma spp., Intracellular organisms (e.g., Bartonella spp. Toxoplasma spp.), and atypical Mycobacteria Oral absorption of azithromycin is high, and it is well tolerated. The drug achieves extremely high tissue concentrations and needs to be given only once daily
  12. 12. Clindamycin Lincomycin Gram pathogens, including staphylococci, streptococci, clostridia, several Actinomyces spp., and some Nocardia spp. very effective against many anaerobic bacteria. Against Toxoplasma gondii, Neospora, and staphylococcal osteomyelitis but ineffective against Gram bacteria. often is used to treat infections resistant to penicillins and erythromycin or patients that cannot tolerate those drugs.
  13. 13. Aminoglycosides Effective against Gram and Gram bacteria, including Enterobacteriaceae and pseudomonads, and have a synergistic effect with β-lactam antibiotics  Anaerobes  lipid insoluble but … Resistant but pleural fluid, bone, joints and peritoneal cavity Dehydration, electrolyte loss, preexisting renal disease, and concurrent use of other nephrotoxic drugs increase nephrotoxicity of aminoglycosides and NSAID
  14. 14. Inhibition of DNA Synthesis Fluoroquinolones Enrofloxacin Difloxacin Ciprofloxacin Ofloxacin Marbofloxacin Potentiated sulfas Trimethoprim-sulfa
  15. 15. Fluoroquinolones
  16. 16. Trimethoprim-sulfonamid : osteomyelitis, prostatitis, pneumonia, tracheobronchitis, pyoderma, urinary tract infections Metronidazole Anaerobic bacteria
  17. 17. DRUGS OF LAST RESORT multidrug-resistant (MDR) Infections Vancomycin, Carbapenems , Oxazolidinone Linezolid , Streptogramin combination of Dalfopristin and Quinupristin , Tigecycline , Lipopeptide Daptomycin , newest Fluoroquinolones Moxifloxacin fourth- and fifth generation Cephalosporins
  18. 18. Dosages of New or Commonly Used Antibiotics in Veterinary Medicine 18
  19. 19. CAUSES OF FAILURE Inappropriate dose frequency, or route of administration inadequate length of treatment inappropriate antibiotic selection persistence of the cause of infection antibiotic resistance incorrect diagnoses depressed host immunity Pharmacokinetics of the drug drug reactions antibiotic antagonism inability of the antibiotic to reach the target tissue
  20. 20. Classification of Surgical Wounds 20
  21. 21. Classifications of Surgical Infections 1. with primary surgical disease (e.g., osteomyelitis that occurs secondary to an open fracture, pyometra, peritonitis that occurs secondary to gastrointestinal perforation, or prostatic abscessation) 2. as a complication of a surgical procedure not commonly associated with infection 3. as a complication of support procedures,with 4. prosthetic implants
  22. 22. Prevention of Surgical Infections Primary objective of aseptic surgery Factors host factors operating room characteristics of bacterial contaminants Proper atraumatic tissue handling and instrument use are also important in preventing infection 22
  24. 24. Antibiotic selection Prevent or treat infection effective VS at least 80% of probable pathogens Staphylococcus spp. (especially coagulase-positive S. aureus), E. coli, and Pasteurella spp. 24
  25. 25. Antibiotic Selection         System involved Cytologic studies Antibiotic reaches target tissue Least expensive, least toxic, and most convenient to administer Timing of Antibiotic Administration Dose Routes of Antibiotic Administration Duration of Antibiotic Administration 25
  26. 26. NOW WHAT ??? 26
  27. 27. 27