Surgical Site Infection and Antibiotic Use Flashcards

1
Q

Define surgical site infection

A

occurs anywhere in the surgical field following a surgical intervention.

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2
Q

How do you categorise a SSI? (3)

A

Superficial incisional SSI
Deep incisional SSI
Organ/space SSI.

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3
Q

Define Superficial incisional SSI

A

These occur within 30 days of surgery and involve only the skin and subcutaneous tissues.

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4
Q

What clinical sign must be present for a superficial incisional SSI?

A

At least one of the following clinical signs must be present:
superficial purulent discharge;
positive culture;
superficial wound dehiscence (or surgical opening);
one of the cardinal signs of inflammation: redness; increased heat; swelling; pain;loss of function.

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5
Q

Define deep incisional SSI

A

These occur within 30 days of surgery, or within 1 year if an implant is present.

They involve the deep soft tissues (fascial and muscle layers) of the surgical incision.

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6
Q

What clinical sign must be present for a deep incisional SSI?

A

At least one of the following clinical signs must be present:

purulent discharge from the deep tissues;

positive culture;

dehiscence (or surgical opening) of the deep incision;

deep abscess.

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7
Q

Define Organ/space SSI

A

These occur within 30 days of surgery, or within 1 year if an implant is present.

They are in any part of the body manipulated during the surgical procedure (except skin, fascia and muscle layers).

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8
Q

What clinical sign must be present for an organ/space SSI?

A

At least one of the following clinical signs must be present:

purulent discharge from the organ/space;

positive culture;

abscess.

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9
Q

How do we classify wounds by contamination?

A

Clean
Clean-contaminated
Contaminated
Dirty.

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10
Q

Define “clean-contaminated” wound

A

These are surgical wounds in which the respiratory, gastrointestinal, urogenital or oropharyngeal tracts are entered under controlled conditions without unusual contamination. This group also includes an otherwise clean procedure in which a surgical drain is placed.

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11
Q

Define “clean” wound

A

These are non-traumatic, non-inflamed surgical wounds in which the respiratory, gastrointestinal, urogenital or oropharyngeal tracts are not entered.

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12
Q

Define “contaminated” wound

A

These are surgical procedures performed on traumatic wounds without purulent discharge, those in which spillage of gastrointestinal contents or infected urine occurs, or those in which there is a major break in aseptic technique.

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13
Q

Define “Dirty” wound

A

These are surgical procedures performed on traumatic wounds with purulent discharge, devitalised tissues or foreign bodies, or those in which a perforated viscus or faecal contamination occurs.

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14
Q

Can you classify these common surgical procedures according to their expected level of contamination?
TPLO

A

Clean

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15
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Spillage of bile in cholecystoenterostomy

A

Contaminated

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16
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Enterotomy

A

Clean-contminated

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17
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Maxillectomy

A

Clean -contaminated

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18
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Debriding necrotic dog bite wound

A

Dirty

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19
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Oropharyngeal stick injury

A

Dirty

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20
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Episiotomy

A

Clean-contaminated

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21
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Placement of chest drain

A

Clean contaminted

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22
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Ruptured pyo

A

Dirty

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23
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Septic peritonitis

A

Dirty

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24
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Suturing traumatic laceration

A

Contaminated

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25
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Scrotal urethostomy with leakage of infected urine

A

Contaminated

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26
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Amputation

A

Clean

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27
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Gastrotomy

A

Clean-contaminated

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28
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Total hip replacement

A

Clean

29
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Enterectomy with GI spillage

A

Contaminated

30
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Internal fix of open #

A

Contaminated

31
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Spay

A

Clean

32
Q

Can you classify these common surgical procedures according to their expected level of contamination?
ruptured liver abscess

A

Dirty

33
Q

Can you classify these common surgical procedures according to their expected level of contamination?
Splenectomy

A

Clean

34
Q

Why does surgery length increase SSI risk? (4)

A

Suppression of the immune system has been correlated with the duration of surgery;
Lengthy surgical procedures expose the wound to microbes for a longer period;
Tissues are handled to a greater degree and can become traumatised or desiccated;
The presence of suture material and orthopaedic implants further reduces the local wound immunity.

35
Q

Why does a prolonged GA increase SSI risk? (5)

A

Prolonged anaesthesia can result in hypotension and hypothermia, resulting in decreased wound perfusion and, hence, local immunity.

Anaesthetic drugs may have a direct effect on the cells of the immune system.

Note: If lengthy diagnostic procedures are required prior to surgery, these may be more safely performed under a separate anaesthetic event.

36
Q

How can the timing of clipping affect chances of an SSI?

A

Clipping of the surgical site any time other than immediately prior to surgery increases the risk of an SSI. This is thought to arise owing to bacterial colonisation of clipper-induced nicks in the skin.

37
Q

Why may propofol increase the risk of an SSI?

A

Propofol is a lipid-based emulsion which promotes bacterial growth and endotoxin formation. Administration of contaminated propofol may promote an SSI.

38
Q

Which 3 endocrinopathies may increase the risk of SSI?

A

hyperadrenocorticism, hypothyroidism and diabetes mellitus

39
Q

What are the statistics between number of people in theatre and SSI?

A

Each person increases SSI by 30%

40
Q

What is the sex predisposition to SSI? Why?

A

Entire male dogs and cats may be at risk of developing an SSI. This is believed to be a direct immunomodulating effect of androgenic hormones.

41
Q

When are peri-operative ABx indicated?

A

When the risk of an SSI is relatively high (clean-contaminated, contaminated and dirty procedures);
When the development of an SSI would be catastrophic.

42
Q

Are ABx warranted?
Suturing contaminated wound

A

Yes

43
Q

Are ABx warranted?
TPLO

A

Yes

44
Q

Are ABx warranted?
Spay

A

No

45
Q

Are ABx warranted?
Simple mastectomy

A

No

46
Q

Are ABx warranted?
Closure of wound over vacuum drain

A

Yes

47
Q

Are ABx warranted?
Internal fixation of closed #

A

Yes

48
Q

Are ABx warranted?
Enterectomy

A

Yes

49
Q

Are ABx warranted?
Castration

A

No

50
Q

Are ABx warranted?
Liver biopsy

A

No

51
Q

Are ABx warranted?
Mast cell tumour removal

A

No

52
Q

Which bacteria is most likely in clean?

A

staphylococci

53
Q

Which bacteria is most likely in clean-contaminated?

A

(for example, upper gastrointestinal procedures) it is most commonly Enterobacteriaceae.

54
Q

Which ABx is the prophylactic of choice - why(2)?

A

Cephalosporins are the prophylactic antibiotic of choice because of their broad spectrum of activity and wide safety margin.

55
Q

What ABx cover if needed for caecum, colon and rectum?

A

Anaerobic too

56
Q

When should prophylactic ABx be given?

A

Typically, this means giving the antibiotic intravenously on induction, followed by repeat doses every 90-120 minutes (as cephalosporins are time-dependent antibiotics). One additional dose may be given after surgery to suppress the late growth of any bacteria not killed during surgery and to minimise contamination from the patient’s environment until the wound has sealed.

57
Q

When should ABx be given after Sx when already given prophylactically?

A

If antibiotics are being used truly prophylactically, then they should not be continued beyond the immediate perioperative period unless there was a major break in aseptic technique or an unexpected change in contamination classification.

58
Q

Define conc dependent ABx.

A

Concentration-dependent antibiotics are those were bacterial killing is dependent on the concentration of the antibiotic above the minimal inhibitory concentration (MIC) of the bacteria at the site of the infection.

59
Q

Define time dependent ABx

A

Time-dependent antibiotics kill bacteria when the concentration of the drug exceeds the MIC. Efficacy correlates with time greater than MIC and is improved by decreasing the dose interval.

60
Q

Does conc or time dependent ABx have a prolonged ABx efficacy

A

Conc

61
Q

Define biofilm

A

A biofilm has been defined as a microbially derived sessile community in which bacteria are attached to a substrate or to each other, are embedded in a matrix, and exhibit altered phenotype (regarding growth, gene expression and protein production).

62
Q

How does a biofilm begin on an implant?

A

with the covering of an implant with a conditioning film derived from the local tissue environment. Bacteria can reversibly adhere to this film (rather than then implant itself).

63
Q

Certain bacteria such as Staphylococcus spp. and Pseudomonas spp. which can create and control the biofilm environment more effectively. How do they make this irreversible?

A

This binding can be made irreversible by the production of bacterial exopolysaccharides known as a glycocalyx. The microbes within the biofilm are sessile and therefore protected from the host’s immune defences.

64
Q

Why are bacteria within a biofilm resistant to ABx? (3)

A

impaired perfusion of the antibiotic agent (owing to the glycocalyx);

the slow bacterial growth rate (as many antibiotics work by interfering with bacterial growth and reproduction);

the adverse environment of the biofilm itself.

65
Q

How do we currently treat implant infections?

A

protracted courses of antibiotics and ultimately explantation of the implant.

66
Q

How can we prevent MRSA? (4)

A

Effective hand hygiene before and after examining patients and the use of protective equipment such as aprons and gloves
Cleaning and disinfection of premises and equipment
The rational use of antibiotics
Compliance with all of the above.

67
Q

When should MRSA be suspected (5)

A

-Animals from MRSA/MRSP positive households
-Animals with non-healing wounds
-Animals with staphylococcal infections that are not responding to antibiotics
-Nosocomial or secondary infections in high-risk patients
-Animals with sepsis.

68
Q

What should you do if you suspect MRSA? (2)

A

C+S!!!
Barrier nurse