Surgical Site Infection

What causes SSI? How do you diagnose SSI? Pathogenesis of SSI?

1. Surgical Site Infection
Ihewa M Gaula MD3

2. Definition
Infections that occur 30 days after surgery with no
implant or 1 year if an implant is placed and infection
appears to be related to surgery

3. Classifications of SSIs
●Etiological classification
●Incisional
●Organ Space Infections
●Time
●Severity

4. Etiological classification
●Primary- occur spontaneously after tissue injury
e.g. stabbing
●Secondary- infection that follow planned
surgical trauma ( operation)

5. Incisional Classification
-superficial ( limited to skin and subcutaneous
tissue)
-Deep ( deep soft tissue: fascia and muscle)

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Criteria for defining SSIs

7. Superficial Incisional SSI
Infection within 30 days after operation and
infection involves only skin or subcutaneous
tissue of the incision and at least one of the
following:
1. Purulent discharge
2. Isolated organisms
3. At least one of the following: pain or
tenderness, localized swelling, redness, or heat

8. Deep Incisional SSI
Infection involves deep soft tissue of the incision and
at least:
1. Purulent discharge
2. A deep incision spontaneously dehisces or is
deliberately opened by a surgeon
3. Patient has at least one of the following: fever,
localized pain or tenderness
4.Abscess or other evidence of infection if examined

9. Organ/Space SSI
Infection involves any part of the anatomy (e.g.
organs or spaces), other than the incision and
at least:
1. Purulent discharge
2. Isolated organisms
3. Abscess- evidence of infection involving
organs/space found on direct examination

10. Time Classification
●Early- within 30 days of procedure
●Intermediate- within one and three months
●Late- more than three months after surgery

11. Severity Classification
●Minor- discharge without cellulitis or deep
tissue destruction
●Major- pus discharge with tissue break down,
partial or total dehiscence of the deep fascial
layers of wound or if there is systemic infection

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13. Pathogenesis
Three elements needed:
1. Infectious agent: identification of pathogen by
smear and culture
2. A susceptible host: immunity issues- specific,
non-specific immunity, closed spaces in tissue,
HIV, DM, etc.
3. A closed un-perfused space: poor perfusion,
local hypoxia, hypercapnia and acidosis in tissues
and wounds

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Virulence
Pathogenesis
Impaired
host resistance
Bacterial dose

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