Lecture 6, Surgical infection and use of antibiotics Flashcards
Surgical site infection (SSI)
Infections that directly result from surgical procedures
- Incisional (actual site of incision)
- Superficial (skin and
subcutaneous tissue) - Deep (deep soft tissue layers
[muscle, fascia])
- Superficial (skin and
- Organ/space (infection of an
anatomic part that was
manipulated) - Infection occurs within 30 days of the surgical procedure or within 1
year if associated with surgical implant - ‘’Nothing spoils a good result as quickly as follow-up“
Problems with SSI
- A rather common complication with potentially devastating results
- Increased treatment duration (costs)
- Frustration (client, veterinarian)
- Patient morbidity and mortality
- Negative public perception
Clinical signs of SSIs
- Redness
- Swelling
- Pain
- Heat
- Serous discharge
- Wound dehiscence
- Fever, weakness, anorexia
Classification of surgical wounds
- Classified by degree of contamination – help predict the likelihood of infection
- Having more than 105 bacteria per gram of tissue – bacterial infection
- Infection rate for all types of surgical wounds approximately 5%
Four categories:
1) clean
2) clean-contaminated
3) contaminated
4) dirty
Clean wounds
- Infection rate 0% – 6%
- Antibiotics usually not warranted
- Prophylactic antibiotics (AB) appear to be indicated in some clean procedures (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 – severe trauma with multiple
fractures, traumatic procedures, orthopedic surgery
Clean-contaminated wounds
- Minor break in aseptic technique
- Infection rate 4.5% – 9.3%
- Antimicrobial prophylaxis indicated
- Choice of antibiotic based on anticipated flora
- Most likely postoperative infection – clean-contaminated fractures of
the pelvis and long bones
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
- Inadequate therapy → dirty wound
Dirty wounds
- Gross infection present at the time of surgical intervention
- (Traumatic wounds with retained devitalized tissue, foreign bodies,
fecal contamination) - Antibiotic therapy, later modified according to culture and sensitivity
results - Copious lavage, debridement
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
4) With prosthetic implants
Primary surgical disease
- Nonsterile source (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)
Notes: Clean-contaminated, prophylactics in case of rupture. If possible to remove the infected part without rupture, there shouldn’t be bacteria and it should be clean, not contaminated.
Does all surgical procedures cause some bacterial contamination?
Yes
What affects the development of infection?
- Number and virulence of the bacteria
- Competence of host defenses
- Amount of tissue damage
- Amount of dead space resulting from the procedure
Complication of a support procedure
- Debilitated, traumatized, immunocompromised patients
- Intravenous catheters
- Cephalic catheters changed every
48 to 72 hours - Jugular catheters changed every 7
to 10 days
- Cephalic catheters changed every
- Urinary catheters
- Common source of infection after
2-3 days
- Common source of infection after
- Prolonged endotracheal intubation (foreign body, disrupted cough reflex)
Prosthetic implants
- 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
- Aseptic technique, AB prophylaxis – infection, implant rejection rare
- (nonabsorbable suture, polypropylene mesh, TTA)
What is the primary objective of aseptic surgery?
Prevention of surgical infections
