Surgical Site Infections
Surgical Site Infections
Surgical Site Infections
DR BASHIRU AMINU
outline
Introduction
Definition
Historical perspective
Epidemiology
pathogenesis
aetiology
Classification
Clinical features
Management
conclusion
introduction
Various classifications
traditional developed in wake of uv light study of
1964
Primarily to provide clinical estimate of inoculum of
bacteria
does not take into cognisance factors like;
virulence, host defences, microenvironment of the
wound
Clean Wounds
does not enter into a colonized viscus or lumen
eg elective inguinal hernia repair
SSI risk is minimal
common pathogen is Staphylococcus aureus
SSI rates is 2% or less
Clean-Contaminated Wounds
enters colonized viscus or cavity under elective
contaminants are endogenous bacteria
Eg sigmoid colectomy wounds contain E coli and
Bacteroides fragilis
Elective intestinal resection, pulmonary resection,
gynecologic procedures, and head-neck cancer op in
oropharynx are examples
Infection rates in the range of 4% to 10%
Contaminated Wounds
gross contamination present in absence of obvious
infection.
eg laparotomy for penetrating injury +intestinal
spillage
contaminants bacteria introduced by gross soilage
Infection rates greater than 10%
Dirty Wounds
active infection is already present
Abdominal exploration for acute bacterial
peritonitis and intra-abdominal abscess are
examples
Pathogens those of active infection
Unusual pathogens are seen
Esp if infection occurred in hospital or nursing home
setting
US CDC developed the NNIS Risk Index system
member hospitals report cumulative data.
A risk index developed to include ;
traditional wound classification system defined
above and additional variables.
This simplified risk index has a range from 0 to 3
points.
A point is added to the patient's risk index for each
of the following 3 variables:
This simplified risk index has a range from 0 to 3
points.
A point is added to the patient's risk index for each
of the following 3 variables
1 point - the patient had operation classified as either
contaminated or dirty.
Organ/Space SSI
Occurs within 30 days of operation or within 1 year if an
implant is present;
Additional treatment
Antibiotic for wound infection 10
Drainage of pus under LA 5
Debridement of wound under GA 10
Serous discharge Daily 0-5
Erythema Daily 0-5
Purulent exudation Daily 0-10
Separation of deep tissues Daily 0-10
Isolation of bacteria 10
Stay greater than 14 days 5
Clinical features
Detailed history
Thorough physical examination
Relevant investigations
Gram stain
Culture (both aerobic and anaerobic)
Sensitivity testing
Antigen and antibody testing
Detecting of RNA and DNA sequencing
PCR
Staining methods;Gram stain
Staining for fungal elements
Culture techniques
Fungal cultures can be requested
Isolation of single colonies allows further growth
and identification of the specific organism.
Sensitivity testing then follows mainly for aerobic
organisms.
Newer techniques ELISA, radioimmunoassay
Detection of antibody in host sera
Detection of RNA or DNA sequences by Northern,
Southern, or Western blotting, respectively
Polymerase chain reaction (PCR)
FBC, FBS, U/E,SERUM PROTEINS
Imaging Studies
Ultrasound can be applied to the infected wound
area to assess whether any collection needs drainage.
MRI, CT SCAN
TREATMENT
Local
-Drainage
-Debridement
Systemic
-resuscitation
-appropriate antibiotics
prevention
Principles
Specific 1- removal of source of infection
2 - block transfer
3 - increase patient resistance
General 1- Infrastructure
theatre design
2 - Administrative policies
antibiotic policies
patients to shower and scrub the surgical site with
antiseptic soap
dont shave or clipp evening before operation.
Nicks and scrapes result in colonization
Depilatory agents recommended
occasionally result in a hypersensitivity
The presence of open skin wounds or infection of the
hands or arms of the surgeon makes postponement
of the operation desirable.
If the patient has any preexisting infection, SSI will
be more likely.
Prevention in the OR begins with the skin
preparation
The site is cleansed with chlorhexidine or
povidone iodine.
Isopropyl alcohol has excellent antiseptic qualities
but is undesirable because of its flammability
Povidone iodine should be allowed to dry before the
incision
use of caps, gowns, masks, and sterile surgical
gloves.
Double gloving prevents blood "strike through" onto
the surgeon's hands
Avoid blood ,fluid breakthrough especially on
surgeon's forearms
Avoid wet drapes
replace soaked gown &drapes.
Wide areas of skin prep around surgical site reduces
risk of breakthrough
Gas sterilization of instruments after thorough
cleansing of any particulate matter
Bowel prep
Achieving hemostasis at the surgical site is
important
process of controlling bleeding may itself increase
infection.
HB in soft tissues or wound space Is potent stimulus
to microbial multiplication
exuberant use of electro cautery leaves necrotic
tissue
Prophylactic antibiotics
Reduces incidence of post-op wound infections
Directed against likely bacteria
Given 30-60mins before operation
Repeated if operation >4hours
– Incision should destroy as little tissue as possible(incision
made through entire skin layer)
- Tissue plane divided with few passes of the knife always
beginning a new pass in the depths of the wound
– Ensure bleeding has stopped before closing wound
Avoid wound edge desication
Proper wound edge apposition
Use of few sutures