Surgical Infection and Use of Antibiotics Flashcards
SSI
Surgical site infection = infections that directly result from surgical procedures.
Infection occurs within 30 days of the surgical procedure or within 1 year if associated with surgical implant.
Surgical site infections are broadly divided into: (2)
Incisional (actual site of incision)
* Superficial (skin and subcutaneous tissue)
* Deep (deep soft tissue layers [muscle, fascia])
Organ/space (infection of an anatomic part that was manipulated)
Clinical signs of SSIs (6+)
- Redness (rubor)
- Swelling (tumor)
- Pain (calor)
- Heat (dolor)
- Serous discharge
- Wound dehiscence
- Fever, weakness, anorexia
Surgical wounds are classified by degree of contamination in order to..?
help predict the likelihood of infection
Infection rate for all types of surgical wounds approximately 5%.
Classification of surgical wound degree of contamination.
Four categories:
1) clean
2) clean-contaminated
3) contaminated
4) dirty
What amount of bacteria equals a full on bacterial infection?
Having more than 10^5 (100,000) bacteria per gram of tissue.
Describe clean surgical wounds.
e.g. elective neuter/spay
Infection rate 0% – 6%.
Antibiotics are usually not warranted.
- Prophylactic antibiotics appear to be indicated in some clean procedures (e.g. orthopedic implants).
- Given at induction (30 to 60 minutes prior to incision).
- Discontinued within 24 hours of the procedure (at the end of surgery).
Most likely postoperative infection occur with severe trauma with multiple fractures, traumatic procedures, orthopedic surgery.
Describe Clean-contaminated wounds.
Minor break in aseptic technique during surgery.
Infection rate 4.5% – 9.3%
- Antimicrobial prophylaxis indicated.
- Choice of antibiotic based on anticipated flora.
Most likely postoperative infection in clean-contaminated fractures of the pelvis and long bones.
Describe Contaminated wounds
Not infected initially, but have the potential.
Infection rate 5.8% – 28.6%.
- Antimicrobial prophylaxis indicated.
- Choice of antibiotic based on anticipated flora, then modified according
to culture and sensitivity results.
Most likely postoperative infection – contaminated fractures of the pelvis
and long bones; contaminated urogenital procedures.
- Delicate debridement, copious lavage, antibiotic therapy → clean wound aka infection resolved or at least under control?
- Inadequate therapy → dirty wound aka infection present
Describe Dirty wounds
Gross infection present at the time of surgical intervention.
(e.g. Traumatic wounds with retained devitalized tissue, foreign bodies,
fecal contamination).
- Antibiotic therapy, later modified according to culture and sensitivity
results. - Copious lavage, debridement required.
Antibiotics used in conjunction with surgeries fall into one of two groups:
prophylactic antibiotics (name is a misnomer)
therapeutic antibiotics
Classifications of surgical infections:
(not the same as classifi. of surgical wounds!)
Surgical infections can occur:
1) With primary surgical disease
2) As a complication of a surgical procedure not commonly associated with infection
3) As a complication of a support procedure e.g. phlebitis from i.v. catheter
4) With prosthetic implants
Describe primary surgical disease
Nonsterile source of bacterial infection (skin, GI tract, urinary tract)
Subject only to surgical treatment not surgical prevention.
AB based on expected bacterial flora – then modified if necessary.
(osteomyelitis secondary to open fracture, pyometra, prostatic abscessation)
Into which category would pyometra surgery belong?
clean-contaminated
(but if its ruptured with poss. peritonitis then contaminated)
Contaminated means…
that there is bacteria present, NOT that there is infection present.
However, wherever there is contamination, there is a high chance of the development of infection.
What factors contribute to development of surgical infection? (4)
- Number and virulence of the bacteria
- Competence of host defenses
- Amount of tissue damage
- Amount of dead space resulting from the procedure
All surgical procedures cause some bacterial contamination!
Describe complications of a support procedure
Debilitated, traumatized, immunocompromised patients.
Intravenous catheters
* Cephalic catheters should be changed every 48 to 72 hours.
* Jugular catheters changed every 7 to 10 days.
Urinary catheters
* Common source of infection after 2-3 days
Prolonged endotracheal intubation (foreign body, disrupted cough reflex).
Describe prosthetic implants and surgical infections.
Implants – foreign substances used to support, rebuild or mimic function of
an anatomic structure.
Foreign material in contaminated/infected wounds increases chance for chronic infection.
- Biofilm = colony of microorganisms, within a matrix of extracellular polymeric substance that they produce (biofilm microorganisms usually resistant to AB).
- AB treatment seldom successful until implant removed (systemic ABs can’t reach an implant that isn’t vascularized).
Aseptic technique & AB prophylaxis reduce infection; implant rejection rare.
(nonabsorbable suture, polypropylene mesh, TTA)
Prevention of surgical infections
Is the primary objective of aseptic surgery.
Factors to be considered
* Age
* Physical condition
* Nutritional status
* Diagnostic procedures
* Concurrent metabolic disorders
* Nature of the wound
* Operating room practices
* Characteristics of bacterial contaminants
Host factors to influence potential for surgical infection/complication: age
- Patients older than 10 years – possible inability to mount an appropriate immune response.
- Patients younger than 1 year – possible underdeveloped immune system.
Host factors to influence potential for surgical infection/complication: physical condition, nutritional status
Increased risk of surgical infection:
* Patients with protein-calorie malnutrition
* Overweight
* Hypoproteinemia
Host factors to influence potential for surgical infection/complication:
diagnostic procedures,
concurrent metabolic disorders
Increased risk of infection:
* Diagnostic procedures (catheterizations, centeses)
* Immunosuppressive therapy
* Previous antibiotic therapy
- Long periods of hospitalization
- Remote infections
- Concurrent debilitating disorders (Cushing’s, DM, protein-losing enteropathy)
Host factors to influence potential for surgical infection/complication: nature of the wound
Allowing bacterial proliferation and inhibiting normal response:
* Presence of necrotic tissue
* Hematoma
- Serum pockets (seroma)
- Local infection
- Foreign bodies
- Dead space
Other factors to influence potential for surgical infection/complication: operating room practice
- Aseptic technique (also drugs [propofol])
- Duration of surgery (teaching hospitals!)
- Risk of infection doubling approximately every 70 minutes
- Duration of anesthesia
- Preparation times should be minimized
- Perioperative warming if necessary
- Proper atraumatic tissue handling
