Infection and Sepsis

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Infection and Sepsis

  1. 1. INFECTION AND SEPSIS <ul><li>Surrounded by pathogens </li></ul><ul><li>Infection is the exception </li></ul><ul><li>Protective from infection </li></ul><ul><ul><li>Physical barriers </li></ul></ul><ul><ul><li>Chemical barriers </li></ul></ul><ul><ul><li>Immunological function </li></ul></ul>
  2. 2. Physical and Chemical Barriers to Infection <ul><li>Skin </li></ul><ul><ul><li>stronger in hands and feet </li></ul></ul><ul><ul><li>sebaceous secretions lower pH </li></ul></ul><ul><li>Mucous membranes </li></ul><ul><ul><li>ciliary function </li></ul></ul><ul><ul><li>mucous barrier </li></ul></ul><ul><ul><li>acid mileu in stomach </li></ul></ul>
  3. 3. Barriers breached in Surgery
  4. 4. Barriers Breached in Trauma
  5. 5. Immune Defense <ul><li>Humoral defense </li></ul><ul><ul><li>antibodies </li></ul></ul><ul><ul><li>complement </li></ul></ul><ul><li>Cellular defense </li></ul><ul><li>Cytokines </li></ul><ul><ul><li>potential for deleterious effects </li></ul></ul><ul><li>Interaction of mechanisms </li></ul>
  6. 6. Breakdown of Host Defense <ul><li>Physical, chemical and immunological breakdown -act synergistically </li></ul><ul><li>e.g. patient with </li></ul><ul><ul><li>diabetes </li></ul></ul><ul><ul><li>immunosuppresion </li></ul></ul><ul><ul><li>surgery </li></ul></ul><ul><li>Potential for deleterious effects </li></ul>
  7. 7. Fourniers Gangrene
  8. 8. Commensal Microbial Flora <ul><li>Important for immune development </li></ul><ul><li>Occupy binding sites for pathogens </li></ul><ul><li>Provide mucobacterial barrier </li></ul><ul><li>Anerobic bacteria </li></ul><ul><ul><li>present in greatest quantity in GIT </li></ul></ul><ul><ul><li>Greatest diversity </li></ul></ul><ul><ul><li>Prevent invasion by gram neg. aerobes </li></ul></ul>
  9. 9. Breakdown of Host Defense - GIT Flora <ul><li>Transmigration of bacteria </li></ul><ul><ul><li>Lack of feeding </li></ul></ul><ul><ul><li>Overuse of antibiotics </li></ul></ul><ul><ul><li>Absence of bile </li></ul></ul><ul><ul><li>Protein malnutrition </li></ul></ul><ul><ul><li>Immune deficiency </li></ul></ul>
  10. 10. ICU patient fed enteraly To preserve GIT integrity
  11. 11. Infection Manifestation <ul><li>Local signs </li></ul><ul><ul><li>pain,redness,swelling, warmth loss of function </li></ul></ul><ul><li>Systemic signs </li></ul><ul><ul><li>Fever, somnolence, confusion, ileus, hypotension </li></ul></ul><ul><li>Lab tests </li></ul><ul><ul><li>TW,­polymorphs, Cultures </li></ul></ul><ul><li>Non infective- causes may manifest as infection </li></ul>
  12. 12. Common Infections <ul><li>Wound infection </li></ul><ul><li>Initial inoculum overwhelms host defense </li></ul><ul><ul><li>Occurs at 5 - 7 days post op </li></ul></ul><ul><li>Factors </li></ul><ul><ul><li>host - immune suppression, DM, renal failure </li></ul></ul><ul><ul><li>surgeon - technique </li></ul></ul><ul><ul><li>environment - contamination </li></ul></ul>
  13. 13. Common Infections <ul><li>Types of Wounds </li></ul><ul><li>1. Clean - no viscus, no sterile breach </li></ul><ul><li>2. Clean contaminated - controlled entry into viscus </li></ul><ul><li>3. Contaminated - emergency bowel resection, perforated appendix </li></ul><ul><li>4. Dirty - heavy contamination / long duration </li></ul><ul><li>Antibiotics used </li></ul><ul><ul><li>type 2 as prophylaxis </li></ul></ul><ul><ul><li>type 3,4 as treatment </li></ul></ul>
  14. 14. Wound Closure <ul><li>Wounds </li></ul><ul><li>Closure by </li></ul><ul><ul><li>primary intention </li></ul></ul><ul><ul><li>secondary intention </li></ul></ul><ul><li>Timing of closure </li></ul><ul><ul><li>delayed primary closure </li></ul></ul><ul><ul><li>secondary closure </li></ul></ul>
  15. 15. Closure by Secondary Intention
  16. 16. Intraabdominal Infection <ul><li>Defense </li></ul><ul><ul><li>Bacterial clearance - stomata between mesothelial cells under diaphragm lead to lymph vessels </li></ul></ul><ul><ul><li>Phagocytosis - both resident and recruited phagocytes </li></ul></ul><ul><ul><li>Sequestration - by fibrin rich inflammatory exudate, with omentum/viscera </li></ul></ul>
  17. 17. Intraabdomianal Infection <ul><li>Signs of peritonitis </li></ul><ul><li>Pain </li></ul><ul><ul><li>sharp in character, well localised at first </li></ul></ul><ul><ul><li>spreads to surrounding areas </li></ul></ul><ul><ul><li>involuntary guarding, rigidity </li></ul></ul><ul><ul><li>absent bowel sounds </li></ul></ul><ul><li>Posture </li></ul><ul><ul><li>lying still, rapid breathing ,no movement </li></ul></ul><ul><li>General condition </li></ul><ul><ul><li>ill, septic, dehydrated, hypotension </li></ul></ul>
  18. 18. Intraabdominal Infection <ul><li>Usually viscus perforation </li></ul><ul><ul><li>colon worse than upper GIT </li></ul></ul><ul><li>Isolates </li></ul><ul><ul><li>aerobic - E. Coli, klebsiella other enterobacter, strep, enterococci, proteus, pseudomonas </li></ul></ul><ul><ul><li>anaerobic - bacteroides, Clostridium </li></ul></ul><ul><li>Treatment is surgical and aggressive antibiotic treatment </li></ul>
  19. 19. Enterocutaneous Fistula
  20. 20. <ul><li>Pneumonia </li></ul><ul><ul><li>Protein malnourished </li></ul></ul><ul><ul><li>upper abdominal wounds ® poor cough </li></ul></ul><ul><ul><li>bed bound - atelectasis </li></ul></ul><ul><ul><li>elderly </li></ul></ul><ul><ul><li>ventilator </li></ul></ul><ul><li>Occurs from 3 days post op </li></ul><ul><ul><li>careful clinical exam,CXR </li></ul></ul><ul><ul><li>Routine chest physiotherapy </li></ul></ul>Common Post Surgical Infections
  21. 21. <ul><li>Urinary Tract Infection </li></ul><ul><ul><li>catheters </li></ul></ul><ul><ul><li>dehydration </li></ul></ul><ul><li>Remove catheters early </li></ul><ul><li>Ensure hydration </li></ul><ul><li>Antimicrobial therapy </li></ul>Common Post Surgical Infections
  22. 22. <ul><li>Catheter and prosthetic devices </li></ul><ul><ul><li>I/v canulas </li></ul></ul><ul><ul><li>central lines </li></ul></ul><ul><ul><li>mesh </li></ul></ul><ul><li>Skin organisms- S aureus, S epidermidis </li></ul><ul><li>Aseptic technique </li></ul><ul><li>Remove if infected </li></ul>Common Post Surgical Infections
  23. 23. Less Common Post Surgical Infections <ul><li>Necrotising soft tissue infection </li></ul><ul><li>Parotitis </li></ul><ul><li>Sinusitis </li></ul><ul><li>Tonsillitis </li></ul>
  24. 24. Treatment of Infection <ul><li>General principles </li></ul><ul><ul><li>incise and drain pus </li></ul></ul><ul><ul><li>antibiotics as needed </li></ul></ul><ul><ul><li>debride dead tissue </li></ul></ul><ul><ul><li>remove foreign bodies </li></ul></ul>
  25. 25. Antibiotic Therapy <ul><li>Prophylaxis </li></ul><ul><ul><li>Short course to prevent infection </li></ul></ul><ul><ul><li>Must be on board before contamination </li></ul></ul><ul><ul><li>Antibiotics with activity against expected inoculation organisms </li></ul></ul><ul><ul><li>Avoid extended spectrum agents </li></ul></ul><ul><ul><li>Post op benefit not proven </li></ul></ul><ul><ul><li>Topical antibiotics - not proven </li></ul></ul>
  26. 26. Antibiotic Therapy <ul><li>Empirical therapy </li></ul><ul><ul><li>based on clinical information </li></ul></ul><ul><ul><li>search for source must continue </li></ul></ul><ul><ul><li>limit duration of empirical therapy </li></ul></ul><ul><ul><li>use known institution pattern of infection </li></ul></ul><ul><ul><li>multi agent vs broad agent </li></ul></ul>
  27. 27. Antibiotic Therapy <ul><li>Directed therapy </li></ul><ul><ul><li>target identified pathogens </li></ul></ul><ul><ul><li>choose suitable efficacy /minimal toxicity agent </li></ul></ul><ul><ul><li>cover aerobic and anaerobic if likelihood exist for both </li></ul></ul><ul><ul><li>extended spectrum as last resort </li></ul></ul>
  28. 28. Multiple System Organ Failure <ul><li>AKA - Gram neg. bacterial sepsis </li></ul><ul><li>30% mortality </li></ul><ul><li>Healthy and compromised host </li></ul><ul><li>3-13 cases per 1000 admissions </li></ul><ul><li>Nosocomial </li></ul>
  29. 30. <ul><li>Factors </li></ul><ul><ul><li>Host compromise </li></ul></ul><ul><ul><li>Elderly, disability </li></ul></ul><ul><ul><li>Malnutrition </li></ul></ul><ul><ul><li>Antimicrobial therapy </li></ul></ul><ul><ul><li>Major surgery </li></ul></ul><ul><ul><li>Cavity manipulation </li></ul></ul><ul><ul><li>Immunosuppression e.g. steroids </li></ul></ul>Multiple System Organ Failure
  30. 31. MSOF <ul><li>Fever </li></ul><ul><li>Acidosis, hypoxemia </li></ul><ul><li>Disordered oxygen and substrate use </li></ul><ul><li>Hyperglycaemia </li></ul><ul><li>Decreased systemic vascular resistance </li></ul><ul><li>Elevated cardiac output </li></ul><ul><li>Hypotension </li></ul>
  31. 32. MSOF <ul><li>Evidence for LPS - endotoxin </li></ul><ul><li>LPS </li></ul><ul><ul><li>O antigen - specific for each organism </li></ul></ul><ul><ul><li>core LPS </li></ul></ul><ul><ul><li>membrane lipid A </li></ul></ul>
  32. 33. LPS - EFFECTS <ul><li>non specific polyclonal b cell proliferation </li></ul><ul><li>macrophage activation, cytokine release </li></ul><ul><li>hypotension, hypoxemia </li></ul><ul><li>bacterial translocation </li></ul><ul><li>complement and coagulation activation </li></ul><ul><li>platelet and white cell margination </li></ul>
  33. 34. LPS - Mechanism <ul><li>Direct effect of bacteria </li></ul><ul><li>Indirect (mediated) effect </li></ul><ul><ul><li>trigger macrophages to release TNFa, IL-1, IL-6, aIFN </li></ul></ul><ul><ul><li>TNFa, IL-1, - primary mediators but may be deleterious in large amounts </li></ul></ul><ul><ul><li>aIFN- causes continued activation of macrophages </li></ul></ul><ul><ul><li>Permeability defects in microcirculation </li></ul></ul><ul><ul><li>ARDS, GUT, Hepatic, renal failure </li></ul></ul>
  34. 35. Problem <ul><li>A 23 year old man had a perforated appendix. Three days post op this was his temperature chart. What is your interpretation. </li></ul>
  35. 36. Problem <ul><li>What is your choice for antibiotic prophylaxis for </li></ul><ul><ul><li>colorectal surgery </li></ul></ul><ul><ul><li>biliary surgery </li></ul></ul><ul><ul><li>upper GI surgery </li></ul></ul>
  36. 37. Problem <ul><li>A 75 year old diabetic had an operation for perforated diverticular disease. His wound was found to be infected on the 5th POD. </li></ul><ul><li>What factors may have contributed to this? </li></ul>

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