1.2 Wound infections (symptoms, treatment)

Question 1

Classification of surgical wounds

Answer 1

surgical wounds are classified based on the level of potential bacterial contamination
- clean wounds
- clean-contaminated
- contaminated
- infected/dirty

Question 2

Characteristics of clean surgical wounds

Answer 2

• most common
• includes all procedures where the GI-tract and billiary tree remains intact
• if contamination occurs, it is gram (+) and derived from the operating room/staff

Question 3

Characteristics of clean-contaminated surgical wounds

Answer 3

• occurs secondary to elective opening of the GI-tract/billiary system
• contamination is from the endogenous flora of the patient

Question 4

Characteristics of contaminated surgical wound

Answer 4

• includes gross spillage of the GI content ie. due to perforation
• contamination can be both endogenous and exogenous
• gross contamination in the absence of obvious infection

Question 5

Characteristics of infected/dirty surgical wounds

Answer 5

• surgical wounds with established (active) infection prior to the procedure
• contamination is polymicrobial and difficult to resolve

Question 6

Pathogens in wound infections

Answer 6

• most common is S. aureus
• others: coagulase (-) streptococci, enterococci, E. coli, P. aeruginosa, enterobacter

**based on surgical field: **
- orthopedic: S. aureus, coagulase (-) streptococci
- appendectomy, colorectal and biliary: gram (-) bacilli, anaerobes
- gastroduodenal: gram (-) bacilli, streptococci
- vascular: S. aureus, gram (-) bacilli
- head and neck: S. aureus, streptococci, anaerobes
- obstetrics/gynecology: gram (-) bacilli, enterococci, anaerobes
- urology: gram (-) bacilli

Question 7

What are surgical site infections?

Answer 7

an infection that occurs within 30 days after the operation and involves the part of the body where the surgery took place

Classifications
- superficial incisional SSI: skin + subcutaneous tissue of the incision
- deep incisional SSI: deep soft tissue (ie. fascia, muscle) of the incision
- organ/space SSI: any other area of the body than skin, muscle and fascia

Question 8

Pathogens of SSI

Answer 8

• skin: staphylococci, streptococci
• oral cavity: staphylococci, streptococci anaerobes
• nasopharynx: staphylococci, streptococci, haemophilus anaerobes
• large bowel: gram (-) rods, enterococci anaerobes

Question 9

Host factors increasing the risk of wound infections

Answer 9

Local
- decreased tissue perfusion, necrosis
- foreign bodies, hematomas, contamination

Systemic
- age extremes
- obesity (poor perfusion)
- malnutrition
- systemic diseases (malignancy, DM, anemia, sepsis, uremia, cachexia)

Question 10

General factors increasing the risk of wound infections

Answer 10

Surgical
- poor surgical skills
- prolonged surgery
- prolonged perioperative hospitalization
- intraoperative contamination, foreign bodies left behind

Multi-resistant pathogens
- doctors contribute by prescribing unnecessary antibiotics
- patients contribute by not adhering to proper usage (ie. using antibiotics when not necessary, not finishing entire course)

Question 11

What are the symptoms of wound infection?

Answer 11

• fever
• hypoventilation
• tachycardia
• SIRS/sepsis
• pus: aerobic infections such as staphylococci or streptococci
• odor: anaerobic infections

Question 12

What is the order of treatment for wound infections?

Answer 12

1. debridement of dead tissue: cleaning and removal of all infected, hyperkeratotic and necrotic tissue
2. disinfection: rinse with hydrogen peroxide
3. empirical antibiotic therapy (broad spectrum): given initially until culture results are available
4. definitive therapy (after culturing)

Question 13

How are contaminated acute wounds managed?

Answer 13

1. traumatic wounds can be closed primarily after adequate debridement by irrigation (except: bite wounds, crushed/ischemic tissue, sustained high level of steroid ingestion and long time lapse since injury – more than 6h)
2. systemic antibiotics are only of use if a therapeutic tissue level cannot be reached within 4 hours of wounding or debridement
3. wound closure: skin sutures of monofilament material have a less chance of becoming infected; porous (full of pores) tape can be used for some wounds
4. contaminated wounds should be checked for infection within 48 hours after closure

Question 14

How are contaminated chronic wounds managed?

Answer 14

1. debridement: excision, frequent dressing changes
2. systemic antibiotics
3. topical antibacterial cream (silver sulfadiazine)
4. biological dressing: can be allograft or xenograft
5. final closure with a flap or skin graft