types of wound contamination and minimising surgical infections

Question 1

what is the definition/threshold for bacterial infection?

Answer 1

Bacterial infection is defined as having more than 105 bacteria per gram of tissue

Question 3

what is a surgical site infection (SSI) ?

Answer 3

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

Question 4

what are the subtypes of SSIs?

Answer 4

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

Question 5

what do SSIs result in?

Answer 5

increased morbidity and mortality in surgical patients

Question 6

what type of SSI accounts for 50% of SSIs?

Answer 6

incisional superficial

Question 7

how are surgical wounds clasified?

Answer 7

Surgical wounds are classified by degree of contamination to help predict the likelihood that infection will develop.
- clean
- clean-contaminated
- contaminated
- dirty

Question 8

what is the definition of a clean wound?

Answer 8

Non-traumatic, non-inflamed operative wounds in which the respiratory, gastrointestinal, genitourinary, and oro-pharyngeal tracts are not entered

Question 9

what are some exaples of a clean wound?

Answer 9

• exploratory coeliotomy
• elective neuter
• total hip replacement

Question 10

what are the infections of clean wounds?

Answer 10

Published infection rates vary from 0 – 4.4%

Question 11

define clean-contaminated wounds?

Answer 11

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

Question 12

what are some examples of clean-contaminated wounds?

Answer 12

• bronchoscopy
• cholecystectomy - removal of gall bladder
• enterotomy - entering small intestine

Question 13

what is the infection rate of clean contaminated wounds?

Answer 13

Published infection rates vary from 4.5 – 9.3%

Question 14

what is the definiton of a contaminated wound?

Answer 14

Open, fresh, accidental wounds; procedures in which gastrointestinal contents or infected urine is spilled or a major break in aseptic technique occurs

Question 15

what is an example of a contaminated wound?

Answer 15

• cystotomy with spillage of infected urine
• open cardiac massage for CPR

Question 16

what is the infection rate for contaminated wounds?

Answer 16

Published infection rates vary from 5.8 – 28.6%

Question 17

what is the definition of dirty wounds?

Answer 17

Old traumatic wounds with purulent discharge, devitalised tissue, or foreign bodies; procedures in which a viscus is perforated or faecal contamination occurs

Question 18

what are some example of dirty wounds?

Answer 18

• excision or drainage of an abscess
• bullae osteotomy for otitis media
• perforated intestinal tract

Question 19

what is the infection rate of a dirty wound?

Answer 19

gross infection present

Question 20

what are the methods of reducing infections during surgery?

Answer 20

• Primary objective of aseptic surgery
• Operating room practice – principles of aseptic technique, sterilisation, disinfection, anaesthesia, atraumatic technique, etc.
• Characteristics of bacterial contaminants (can they be managed with broad spectrum antibiotics)

Question 21

what host factors have a role in post surgical infection?

Answer 21

• Age
• Physical condition
• Nutritional status
• Diagnostic procedures
• Concurrent metabolic disorders (hyperadrenocortisism)
• Current medication (corticosteroids, chemotherapy)

Question 22

when should antibiotics be used after surgical oprations?

Answer 22

• Surgery time longer than 90 minutes
• Prosthesis implantation – mesh, pacemaker, bone cement, etc.
• Patients with a pre-existing prosthesis (e.g. hip replacement) undergoing certain surgical procedures (e.g., dental prophylaxis, traumatic wounds, colorectal surgery)
• Severely infected or traumatised wounds

must use rational selection of antibiotics for prophylactic use
* Definitive choice would depend of culture & sensitivity results

Question 23

what are prophylactic antibiotics for surgical use, administed in small animals and why is this done?

Answer 23

intravenous as this allows for the highest conc to bbe circulating at time of contamination (operation) - however there is only a small amount of chocie

Question 24

what type of prophylatic antibiotic is used for surgical use for small animals?

Answer 24

2nd generation cephalosporin eg Cefuroxime (zinacef) (gram positive)
or
amoxicillin and clavulanic acid eg augmentin (gram positive)

Question 25

what type of antibiotic is Zincef? and what does it work against?

Answer 25

Cefuroxime (a cephalosporin) - broad spec - gram positive

Question 26

wha type of antibiotic is augmentin

Answer 26

amoxicillin and clavulanic acid - broad spec - gram positive

Question 27

what antibiotic would you use for anaerobic organisms?
eg for prophylatic use if operating on large intestine

Answer 27

metronidazole

Question 28

what three antibiotics are used prohylaticially for surgery in equines?

Answer 28

• procaine penicillin (IV)
• gentamicin (IV)
• Oxytetracycline (Engeemycin) (SQ)