Wound Contamination

Question 1

What is a bacterial infection?

Answer 1

When there is >10^5 bacteria per gram of tissue

Question 2

What is an SSI?

Answer 2

Surgical Site Infection
An infection related to surgical intervention
Infection of tissues, organs or spaces exposed by surgeon during an invasive procedure
Result in increased morbidity and mortality

Question 3

What are the subtypes of SSIs?

Answer 3

incisional infections - superficial (most common), deep incisional
Organ/space infection - e.g. peritoneal cavity

Question 4

What are the classifications of surgical wounds?

Answer 4

Clean
Clean-contaminiated
Contaminated
Dirty

Question 5

Clean wound

Answer 5

Non-traumatic
Non-inflamed
when respiratory, gastrointestinal, genitourinary and oro-pharyngeal tracts have NOT been entered
Examples:
Exploratory celiotomy/laparotomy
Elective neuter
Total hip replacement
0-4.4% infection rate

Question 6

Clean-contaminated wound

Answer 6

When respiratory, gastrointestinal, genitourinary and oro-pharyngeal tracts have been entered under controlled conditions
No unusual contamination
All other aspects considered a clean procedure
Examples:
Bronchoscopy
Cholecystectomy
Enterotomy
4.5-9.3% infection rate

Question 7

Contaminated wound

Answer 7

Open, fresh, accidental wounds
Procedures in which GI contents or infected urine is spilled
OR a major break in aseptic technique occurs
Examples
Cystotomy with spillage of infected urine
Open cardiac massage for CPR
5-8-28.6% infection rate

Question 8

Dirty wound

Answer 8

Old traumatic wounds with purulent discharge, devitalised tissue, foreign bodies
Procedures in which a viscera is perforated
SI or uterus
Faecal contamination occurs
Examples
Excision or drainage of abscess
Bullae osteotomy for otitis media
Perforated intestinal tract
Gross infection is present

Question 9

Host factors affecting infection risk:

Answer 9

Age
Old animal - may not be able to fight infections off
Young animal - underdeveloped immune system
Physical condition
Cachexia - weakness/wasting of body due to severe illness
Malnourished
Nutritional status
Diagnostic procedures
Placed catheters which could increase risk of infection
Concurrent metabolic disorders
Hyperadrenocorticism (Cushing’s) - corticosteroids present
Current medication
Corticosteroids
Chemotherapy

Question 10

Methods of reducing surgical infections

Answer 10

• Patient prep
  ○ Clipping
  ○ Scrubbing
  ○ Draping
  
  • Surgeon prep
    ○ Scrubbing
    ○ Gowning
    ○ Gloving
    ○ Hats
    ○ Masks
  • Theatre behavious
    ○ Etiquette - aseptic technique
    ○ Talking
    ○ Air flow

Question 11

When are antibiotics used in surgery?

Answer 11

Mostly when procedures are within contaminated and dirty categories
Occasionally in clean-contaminated procedures
Rarely in clean operations
When surgery > 90 minutes
Prosthesis implantation
Pacemaker
Mesh
Bone cement
Patients with pre-existing prosthesis
Hip-replacement
Severely infected traumatised wounds

Choice of antibiotic depends on culture and sensitivity results

Question 12

Types of antibiotic in SA Medicine

Answer 12

Cephalosporin
Broad-spectrum, good against gram +ve
Clavulanate amoxicillin
Broad-spectrum, good against game +ve
Reasonable action against aerobic organisms
Metronidazole
Better for anaerobic organisms

Question 13

Types of antibiotic in Equine medicine

Answer 13

• IV
  ○ Procaine penicillin
  ○ Gentamicin
  
  • Non-IV
    ○ Oxytetracycline