surgical site infections
TRANSCRIPT
Surgical Site Infection
Dr. Hany Lotfy MDAssistant professor of medical microbiology and Immunology
Sulaiman Al Rajhi Colleges
2015
Surgical Site Infections (SSI)
Second most common nosocomial infection (17%). Most common nosocomial infection among surgical
patients (38%).2/3 incisional.1/3 organs or spaces accessed during surgery.
About 300,000 SSIs occur each year. Prolong hospital stay by 7.4 days.
Definition
A surgical site infection (SSI) is an infection that
occurs after surgery in the part of the body
where the surgery took place.
Colonization vs Contamination.. Definitions
Colonization: Bacteria present in a wound with no signs or symptoms of
systemic inflammation. Usually less than 105 cfu/mL.
Contamination: Transient exposure of a wound to bacteria. Varying concentrations of bacteria possible. Time of exposure suggested to be < 6 hours. SSI prophylaxis best strategy.
SSI – Definitions
Infection: Systemic and local signs of inflammation. Bacterial counts ≥ 105 CFU/mL.
1. Superficial Incisional SSI
Infection occurs within 30 days after the operation and involves only skin or subcutaneous tissue of the incision.
Subcutaneous tissue
SkinSuperficial incisional SSI
2. Deep Incisional SSI
Infection occurs within 30 days after the operation if no implant is left in place or within 1 year if implant is in place.
The infection appears to be related to the operation and the infection involves the deep soft tissue (e.g., fascia and muscle layers).
Deep soft tissue (fascia & muscle)
Deep incisional SSI
Superficial incisional SSI
3. Organ/Space SSI
Infection occurs within 30 days after the operation if no implant is left in place or within 1 year if implant is in place and the infection appears to be related to the operation.
Infection involves any part other than the incision, which was opened or manipulated during the operation
Deep incisional SSI
Superficial incisional SSI
Organ/space SSIOrgan/space
Sources of SSI Pathogens
1. Endogenous flora of the patient.
2. Operating theater environment.
3. Hospital personnel.
4. Seeding of the operative site from distant focus of infection (prosthetic device, implants).
Classification and Rates of SSIClass Type Description %
I Clean An uninfected operative wound without inflammation.
No intrinsic bacterial flora
8 %
II Clean / contaminated
Operative wounds in which the respiratory, alimentary, genital, or urinary tracts are entered under controlled conditions and without unusual contamination.
Operations involving the biliary tract, appendix, vagina, and oropharynx
22%
III Contaminated Open, fresh, accidental wounds. Involves spillage of viscus content.
30%
IV Dirty Old traumatic wounds with retained devitalized tissue and those that involve existing clinical infection or perforated viscera.
40%
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”Etiology of SSI
Most Common Pathogens Associated With Nosocomial Infections
Pathogen All Sites BSI Pneumonia SSIn=235,758 n=50,091 n=64,056 n=22,043
Coag-neg Staph 14.3 39.3 2.5 13.5S aureus 11.4 10.7 16.8 12.6Enterococci spp. 8.1 10.3 1.9 14.5P. aeruginosa 9.9 3.0 16.1 9.2Enterobacter spp. 7.3 4.2 10.7 8.8E. coli 7.0 2.9 4.4 7.1C. albicans 6.6 4.9 4.0 4.8K. pneumoniae 4.7 2.9 6.5 3.5Others 30.7 21.8 37.1 26.0
Relative Percentage by Site of Infection
BSI=bloodstream infection; SSI=surgical site infection.Fridkin SK et al. Clin Chest Med. 1999;20:303-316.
“
”SSI – Risk Factors
A. Operation Factors
Duration of surgical scrub. Skin antisepsis. Preoperative shaving. Duration of operation. Antimicrobial prophylaxis. Operating room ventilation Inadequate sterilization of
instruments.
Foreign material at surgical site.
Surgical drains. Surgical technique:
Poor hemostasis. Failure to obliterate dead space. Tissue trauma.
B. Patient Factors
Age Increasing age. Diabetes. Smoking: delays primary
wound healing. Steroids. Malnutrition. Obesity. Prolonged preoperative stay.
Preoperative colonization with S. aureus.
Perioperative transfusion. Coexistent infections at a
remote body site. Altered immune response.
Bacterial dose Virulence
Impairedhost resistance
Risk of Infection
Bacterial dose Virulence
Impairedhost resistance
Risk of Infection
Bacterial dose Virulence
Impairedhost resistance
Virulence
Impairedhost resistance
Risk of InfectionRisk of Surgical Infection
Bacterial dose
“
”Diagnosis of SSI
1. Clinical picture
The typical features of wound infections: Increased exudate. Increased swelling. Increased erythema. Increased pain. Increased local temperature. Peri-wound cellulitis, change in appearance of granulation tissue
(discoloration, prone to bleed, highly friable). The failure of the wound to heal and progressive deterioration of
the wound.
Clinical picture
2. Laboratory
ESR…… ↑ Complete blood picture:
WBC…… ↑ CRP. Microbiological.
Sample:
Pus or exudates from infected wounds is usually sampled by swabbing deep in the wound, which must be soaked well in the exudates.
A specimen of the pus itself is always preferred and can be obtained by using a syringe and transfer to a sterile tube or screw capped bottles.
Pieces of tissues removed at operation are sent to the laboratory for bacterial examination, these tissues are homogenized in a tissue grinder with a little broth.
Specimen Collection:
The gold standard collection method is to do a
tissue biopsy or needle aspirate of the leading
edge of the wound after debridement.
If a tissue biopsy is not possible????
Cleanse the wound with sterile saline Vigorously swab the base of the lesion Surface wounds place the swab in a sterile
container for transport. Deep wounds place the swab in a sterile anaerobic
container for transport.
SAMPLING
Laboratory
Transfer swab
Bedside culture
Transport media
In the laboratory
1. Culture on suitable media.
2. Incubation:
Aerobic.
Anaerobic.
3. Identification of the organism.
4. Antibiotic sensitivity test.
“
”Prevention of SSI
Pre-operative
Avoid antibiotics. Minimize hospitalisation. Treat any remote infection. Avoid shaving. Chlorhexidine bath. Resolve obesity/malnutrition. Control smoking. Control diabetes.
Intra-operative
Skin preparation. Aseptic technique. Filtered air in operation room (OR). Antibiotic wound irrigation. Isolate clean / dirty surgical fields. Minimize drains. Minimize dead space haematomas and devitalised
tissue.
Post-operative
Proper dressing. Minimize catheters & IV lines.
Maintain oxygenation. Maintain hydration & nutrition. Antibiotic.
“
”TREATMRNT of SSI
Treatment
1. PREVENTIVE.2. Remove foreign bodies.3. Remove necrotic tissues.4. Antiseptics.5. Antibiotic sensitivity test……