types of wound contamination and minimising surgical infections

Question 1

Define bacterial infection

Answer 1

having more than 10^5 bacteria per gram of tissue

Question 2

Define SSI (surgical site infections)

Answer 2

infections of the tissues, organs, or spaces exposed by surgeons during performance of an invasive procedure

Question 3

What are the subtypes of SSIs

Answer 3

Incisional:
- Superficial (limited to skin and subcutaneous tissue)
- Deep incisional
Organ/space infections

Question 4

Describe the classification of surgical wounds by degree of contaimination

Answer 4

Clean
Clean contaminated
Contaminated
Dirty

Question 5

Describe a clean wound with examples

Answer 5

Non-traumatic, non-inflamed operative wounds in which the respiratory, gastrointestinal, genitourinary, and oro-pharyngeal tracts are not entered
e.g., elective neuter, total hip replacement, exploratory coeliotomy
Infection rate - 0-4.4%

Question 6

Describe a clean-contaminated wound with examples

Answer 6

Operative wounds in which the respiratory, gastrointestinal, or genitourinary tract are entered, but under controlled conditions without unusual contamination; an otherwise clean wound in which a drain is placed
e.g., bronchoscopy, enterotomy, cholecystectomy (gall bladder)
Infection rates 4.5-9.3%

Question 7

Describe contaminated wounds with examples

Answer 7

Open, fresh, accidental wounds; procedures in which gastrointestinal contents or infected urine is spilled or a major break in aseptic technique occurs
e.g. cystotomy with spillage of infected urine, open cardiac massage for CPR
Infected rates from 5.8-28.6%

Question 8

describe dirty wounds with examples

Answer 8

Old traumatic wounds with purulent discharge, devitalised tissue, or foreign bodies; procedures in which a viscus is perforated or faecal contamination occurs
e.g. excision or drainage of abcess, operated on middle ear, perforated intestinal tract
Gross infection is present

Question 9

What host factors can affect the incidence of SSIs

Answer 9

age (very young or old)
physical condition (malnourished? obese?)
nutritional status
diagnostic procedures (e.g, catheters)
concurrent metabolic disorders
current medication (e.g., corticosteroids increase risk of infection)

Question 10

What factors affect SSI incidence?

Answer 10

Host factors
Operating room practice
Characteristics of bacterial contaminants

Question 11

When should antibiotics be used to avoid SSIs

Answer 11

Surgeries longer than 90 minutes
Prosthesis implantation e.g., pacemaker (can become a harbour for bacteria)
Patients with pre-existing prosthesis
Severely infected or traumatised wounds