• 75% of nosocomial infections occur in surgical patients
• Most postoperative infections arise from patients own flora
• Commonest sites of infection are:
  • Urinary tract  (40%)
  • Respiratory tract (15%)
  • Bacteraemia (5%)

Normal body flora

• Skin - staphylococci, streptococci
• Oral cavity - staphylococci, streptococci and anaerobes
• Nasopharynx - staphylococci, streptococci, haemophilus and anaerobes
• Large bowel - gram-negative rods, enterococci and anaerobes
• Urinary tract - normally sterile

Sources of wound contamination

• Direct inoculation
  • Patients residual flora or skin contamination
  • Surgeon's hands
  • Contaminated instruments or dressings
  • Contaminated procedure
  • Drains, catheters or intravenous lines
• Airborne contamination
  • Skin and clothing of staff and patients
  • Air flow in operating theatre or ward
• Haematogenous spread
  • Intravenous lines
  • Sepsis at other anatomical sites

Bibliography

Leaper D J.  Risk factors for surgical infection.  J Hosp Infect 1999;  30 (Suppl):  S127-139