Surgical Infections Flashcards
What is an infection?
Invasion of the body by pathogenic microorganisms and reaction of the host to organisms and their toxins
What is a surgical infection?
an infection requiring surgical treatment and has developed before or as a complication of surgical treatment
< 30 days of surgery (or within a year in the case of implants)
Name types of infections in surgery?
- Wound infections
- Surgical site infections
- Superficial
- Deep - Soft tissue infections
- Cellulitis
- Subcutaneous abscesses
- Peri-anal or perirectal abscesses
- Pyomyositis
What are superficial incisional surgical site infections?
- 30 days of procedure
- involve only the skin or subcutaneous tissue around the incision.
What are deep incisional surgical site infections?
- < 30 days of procedure (or one year in the case of implants)
- are related to the procedure
- involve deep soft tissues, such as the fascia and muscles.
Name local factors influencing surgical site infections: surgical + paient?
- High bacterial load
- Wound hematoma
- Necrotic tissue
- Foreign body
- Obesity
Systemic factors contributing to infection?
- Advanced age
- Shock
- Diabetes
- Malnutrition
- Alcoholism
- Steroids
- Chemotherapy
- Immuno-compromise
Surgical risk factors for infections?
- Type of procedure
- Degree of contamination
- Duration of operation
- Urgency of operation
- skin preparation
- operating room environment
- Antibiotic prophylaxis
Pathogenicity of bacteria?
- exotoxins
- endotoxins
- resist phagocytosis
Exotoxins?
specific, soluable proteins, remove cytotoxic effects
e.g. Tetani, strept pyrogens
Endotoxins?
part of gram neg bacteria wall
e.g. E.coli
Resist phagocytosis?
protective capsule
i.e klebsiela and strept. pneumonia
What is host resistance?
- Intact skin (surgery/ trauma breaks it)
- Immunity : cellular, antibodies
How to prevent surgical infections?
- Have good host defences
- Minimise pathogens during surgery
- Good surgical techniques
- Perioperative surgical care
Classification of the type of surgery?
- clean
- clean contaminated
- contaminated
- dirty
What is a clean surgery?
- uninfected operative (non traumatic) wound
- no acute inflammation
- no entry to internal organs and no break in aseptic technique
e.g. hernia repair, mastectomy, vascular
Note: infection rate is 2%
What is a clean-contaminated surgery?
- opening to internal organ but minimal or no spillage of contents
- respiratory, GI, GU tract entered with minimal contamination
- no evidence of infection or major breakage in aseptic technique
e.g. cholecystectomy, lysis of adhesions, gastrectomy, hysterectomy
Note: infection <10%
What is a contaminated surgery?
- open, fresh, traumatic wounds
- opening to internal organs with inflammation or uncontrolled spillage of contents
- minor break in sterile technique
e.g. colectomy for obstruction, rupture appy, emergent bowel resect
Note: 20%
What is dirty surgery?
- open, traumatic, dirty wounds
- traumatic perforation of hollow viscus with peritonitis
- purulent inflammation present
- intraperitoneal abscess formation : frank pus in field
e.g. perforated appendicitis, intestinal fistula resection
Note: infection rate is 28-70%
Surgical site infections and tissue layers affected?
- superficial incisional
- skin + subcutaneous tissue - deep incisional
- skin, subcutaneous tissue + deep and soft tissue (fascia and muscle) - organ space
- organ space
What is necrotizing fascitis?
It is necrosis of superficial fascia overlying the skin
- Worse in diabetics
- Starts as cellulitis
e.g. Polymicrobial: strept, staph, enterococci, enteriobacterioceae
Common sites for necrotizing fascitis?
1.Abdomen - meleny
2. perinum - fourniers
3. limb
Treatment of necrotizing fascitis?
- Debridement
- wound dressing antibiotics
- skin grafting
Incidence of SSIs when you take into account opening and re-closure times of an infected wound?
- opening and reclosure at once - 50%
- opening and re-closure after 2 days - 20%
- opening and re-closure after 4 days - 5%
- opening and re-closure after 9 days - 10%
