Antimicrobial Prophylaxis in Surgery To prevent wound

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Antimicrobial Prophylaxis in Surgery

• To prevent wound infection during or after
  surgical procedures.

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Factors responsible for wound infection

• Critical number of bacteria present in the wound
  at the time of closure.
• Virulence of the bacteria.
• Presence of devitalized or poor vascularized
  tissue
• Presence of a foreign body
• Status of the host immunocompromised.

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Risk Factors for wound infection

• Operations on the abdomen,
• Operations lasting more than 2 hours,
• Contaminated or dirty wound,
• At least three medical diagnoses,
• Open heart surgery,
• Clean procedures that involve placement of
  prosthetic materials

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Chemoprophylaxis During Surgery

• Chemoprophylaxis is frequently successful, if a
  single, effective, nontoxic drug is used to
  prevent infection by the specific micro-organisms
  or to eradicate an early colonization or
  infection.

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Effective Surgical Chemoprophylaxis

• Antimicrobial activity must be present at wound
  site at the time of closure.
• Drug should be given immediately preoperatively,
  i.e., 30 to 60 min. before incision and
  intra-operatively for long procedures.
• Antibiotic active against most likely
  contaminating micro-organisms.
• Cephalosporins commonly used
• Administered by intravenous route.
• Use beyond 24 hours is unnecessary except in
  dirty and contaminated procedures.

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Cephalosporins

• First source Cephalosporium acremonium (Fungus)
• Active nucleus 7-aminocephalosporanic acid
• ?-Lactam antibiotics
• Stable in acid
• Resistant to beta-lactamases

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Classification of Cephalosporins

• First Generation
• Cefazolin
• Cephalexin
• Useful Spectrum
• Streptococci
• Staphylococcus aureus

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Second Generation

• Cefuroxime
• Cefaclor
• Cefoxitin
• Cefotetan
• Useful Spectrum
• E.coli, Klebsiella, Proteus, H. influenza
• Bacteroides spp., other anaerobes
• Not as active against Gram ve

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Third Generation
Cefotaxime Ceftriaxone
Ceftazidime Useful Spectrum
Enterbacteriaceae Pseudomonas aeruginosa
N. gonorrhoeae Staphylococci, Streptococci
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Fourth Generation

• Cefepime
• Useful Spectrum
• Similar to 3rd generation
• More resistant to ?-Lactamases

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Cephalosporins

• Mechanism of Action
• Cell wall synthesis inhibitors
• (like penicillin)
• Inhibit Transpeptidation reaction
• (Final step in cell wall synthesis)

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Cephalosporins

• Development of Resistance
• Reduced permeability
• Reduced binding to Pencillin Binding Proteins
  (PBPs)
• ?-Lactamases

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Cephalosporins

• Ineffective Against
• Enterococci, Legionella
• Methicillin-resistant S. aureus
• Penicillin-resistant S. pneumoniae
• C. difficile
• Campylobacter jejuni

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Pharmacokinetics

• Orally Effective
• - Cephalexin, Cefaclor, Cefuroxime axetil
• Others I.V. Or I.M.
• Excretion Renal
• Biliary Cefoperazone
• Distribution CSF - Cefuroxime
• - Cefotaxime
• - Ceftriaxone
• - Cefepime

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Cephalosporins

• Adverse Effects
• Hypersensitivity Reactions
• Anaphylaxis
• Bronchospasm
• Urticaria
• Rashes
• Fever
• Cross-Reactivity with Penicillin 10
• Nephrotoxicity
• Diarrhoea
• Hypoprothrombinemia
• Thrombocytopenia

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Guidelines for Surgical Chemoprophylaxis

• Nature of Operation
• Clean
• Thoracic, Cardiac,
• Vascular, Orthopedic
• Neurosurgery.

• Recommended Drugs
• Cefazolin
• Vancomycin

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Clean - Contaminated

• Head Neck Surgery
• Abdominal
• (Upper GI, Biliary)
• Abdominal
• (Appendectomy)
• Colorectal
• Gynecological

• Cefazolin
• Cefazolin
• Cefoxitin or Cefotetan
• or
• Cefuroxime
• Metronidazole
• Cefazolin

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Trauma-Contaminated

• Extremity
• Abdomen/Bowel Injury
• Bites

• Cefazolin
• Vancomycin
• Cefotetan or
• Cefoxitin or
• Gentamicin
• Metronidazole
• Amoxicillin - Clavulanate