Perioperative Antibiotics & SSI

Question 1

________ is bacteria on a surface of a tissue

Answer 1

contamination

Question 2

_________ is when bacteria recognizes a tissue by receptors, invades the tissue, proliferates within the tissue, and subsequently the tissue becomes inflamed.

Answer 2

Infection

Question 3

What 1 or more factors does the CDC define as a surgical site infection?

Answer 3

purulent drainage
bacteria aseptically cultured
heat, redness, pain, or local swelling AND the incision was reopened by the Dr. unless culture was negative.
Doctor diagnoses SSI

Question 4

What is the key point to diagnosing a surgical site infection?

Answer 4

Normal healing in a healthy individual takes 7-14 days. If inflammation is exceeding what you would expect as a surgeon (inflammation, bruising, pus, etc.), then a SSI is likely occuring.

Question 5

T/F: contamination is always occuring even if the surgery is clean.

Answer 5

true

Question 6

what is the % risk of infection from an uncomplicated CLEAN surgery?

Answer 6

2.5-4.8%

Question 7

Why do we not give antibiotics to every surgical patient?

Answer 7

because while all wounds become contaminated with bacteria, only a very small portion of them become truly infected.

Question 8

What are 10-12 risk factors for SSI?

Answer 8

1. higher NRC classification
2. longer surgery time and anesthesia time
3. clipping prior to induction
4. endocrinopathies (hyperadrenocorticism and hypothyroidism)
5. obesity
6. # people in OR
7. propofol induction
8. foreign material / implants
9. bulldog
10. intact males
11. tissue health*
12. host immunity (neoplasia, age, etc.)

Question 9

Describe how clipping hair prior to surgery increases risk for SSI?

Answer 9

clipping causes micro-cracks within the skin that bacteria can colonize

Question 10

What 2 endocrinopathies have shown increased risk for SSI in dogs?

Answer 10

hyperadrenocorticism
hypothyroidism

Question 11

Regardless of the MANY known risk factors for SSI’s, what are the 2 most important things you can do to prevent SSI?

Answer 11

1. aseptic technique
2. maintain healthy tissue through gentle tissue handling

Question 12

Why can we not just rely solely on antibiotics to prevent or reduce risk of SSI? (3 reasons)

Answer 12

antibiotics do NOT kill all bacteria
antibiotics kill resident “good” bacteria
antibiotics cannot kill bacteria in devitalized tissue, fluid pockets, and/or biofilms on implants.

Question 13

What are Halsted’s principles of maintaining good tissue health?

Answer 13

1. gentle tissue handling
2. control hemorrhage
3. aseptic technique
4. preserve blood supply to tissues
5. eliminate dead space
6. appose tissues with minimal tension

Question 14

How can you differentiate a sterile seroma from an abscess?

Answer 14

sterile seroma - will not feel hot or be painful
abscess – hot, painful, and may be odorous or causing systemic signs.

if there is fluid dripping, you can sample the fluid and if there are neutrophils and bacteria its an abscess, if there is proteinaceous material, its a sterile seroma.

Question 15

What is the difference between prophylactic and therapeutic antibiotics?

Answer 15

prophylactic: PREVENT infection from occuring and are only given DURING surgery
therapeutic: TREAT infection and a full course if given, which would extend beyond surgery.

Question 16

When should you use both prophylactic and therapeutic antibiotics?

Answer 16

a dirty surgery such as a pyometra, cystotomy, dirty wounds, etc.

controverisal whether or not both are required for contaminated surgeries.

Question 17

when should you use neither prophylactic nor therapeutic antibiotics?

Answer 17

clean surgeries

Question 18

when should you consider using only prophylactic antibiotics?

Answer 18

clean-contaminated surgeries

Question 19

What are the 3 principles of prophylactic antibiotics?

Answer 19

1. target the expected bacteria (ex. skin –> gram + –> cephalosporins)
2. ensure peak tissue concentration at time of incision and throughout period of contamination
3. d/c within 24 hr of sx

Question 20

T/F: all resident flora remain after aseptic surgical site prep

Answer 20

false – only 20% remain and there are usually beneath the surface of the skin within the hair follicles. clipping and scrubbing only removes surface flora.

Question 21

what is the MOST commonly used perioperative antibiotic that is good for target bacteria?

Answer 21

cefazolin

Question 22

what is the rule of thumb for redosing antibiotics during surgery?

Answer 22

redose every 2 half-lives for as long as the incision is open.
ex. cefazolin’s half life is ~47 min, so this drug is redosed every 90 minutes during surgery.

Question 23

T/F: prophylactic antibiotics are indicated in ALL surgeries

Answer 23

false – they are only indicated when:
1. infection risk is high
2. NRC classification is clean-cont. or higher
3. consequences of infection would be disastrous

Question 24

Why are postoperative antibiotics not indicated for prophylaxis?

Answer 24

antibiotics kill good bacteria too! when the good resident bacteria are killed off, pathogenic bacteria are able to invade.

Question 25

what are the exceptions to using postoperative antibiotics for prophylactic purposes?

Answer 25

1. SOME implants
2. devitalized tissue or dead space that you cannot eliminate

Question 26

when are postoperative antibiotics indicated?

Answer 26

in patients WITH ACTIVE INFECTION

Question 27

What NRC classification is a spay?

Answer 27

clean

Question 28

what NRC classification is a cystotomy?

Answer 28

clean contaminated, so prophylactic antibiotics are indicated unless the patient does NOT have a UTI.

Question 29

what NRC classification is a total hip replacement?

Answer 29

clean and antibiotics are NOT indicated, unless an implant is being placed, then antibiotics are indicated because if infection were to occur, the consequences would be disastrous