3.Antimicrobial selection in Sugery styu.pdf

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1. ANTIMICROBIAL PROPHYLAXIS IN
SURGERY

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2. INTRODUCTORY CASE
MR., a 72-year-old woman, is admitted to the hospital with
severe abdominal pain, nausea and vomiting, and
temperature of 39.3°C. A diagnosis of acute cholecystitis is
made, and M.R. is scheduled for biliary tract surgery
(cholecystectomy).
What is the CDC wound class of MR?
Does MR warrant an antimicrobial prophylaxis? Why?
Which antimicrobials are preferred?
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3. EPIDEMIOLOGY
Infection is the most common complication of surgery.
Surgical site infections (SSIs):
Occur in approximately 3% to 6% of patients
Prolong hospitalization by an average of 7 days
Increase direct annual cost of $5 billion to $10 billion.


SSIs are the third (14–16%) most frequent cause of
nosocomial infections among hospitalized patients
The primary (40%) cause of nosocomial infection in
surgical patients.
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4. EPIDEMIOLOGY…
The inappropriate or indiscriminate use of prophylactic
antibiotics can increase:
The risk of drug toxicity
Selection of resistant organisms
Costs.
But appropriate Prophylactic administration of antibiotics
Decreases the risk of infection after many surgical procedures
Represents an important component of care for this
population

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6. NATIONAL RESEARCH COUNCIL WOUND CLASSIFICATION, RISK
OF SURGICAL SITE INFECTION, AND INDICATION FOR
ANTIBIOTICS

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a-implantation of prosthetic materials

7. PATIENT AND OPERATION CHARACTERISTICS THAT INFLUENCE SSI
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11. TIME OF INFECTION AFTER SURGERY
Most incision site infections within 30 days.

Some deep seated infection within weeks to months.

Implants within infections occur up to year
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13. BACTERIOLOGY
Bacteria in skin: Staph. aureus, so any incision can lead
to inoculation of bacteria and cause infection.
Patient with psoriasis or eczema, their skin heavily
colonized with bacteria: increase risk for wound
infection,
So use preoperative skin disinfectant to reduce the
infection.
Large colon highly colonized: use Purgative to reduce
contamination in colonic of rectal surgery also we use
antibiotic prophylaxis.
Also nurse heavily colonized with Staph. aureus and act
as source of infection
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15. CONSEQUENCES OF INFECTION
Skin and superficial soft tissue infection: impair
aesthetic quality of surgical scar.
Deeper soft tissue infections: cellulitis & abscess
formation.
Infection of bone & joint prostheses: long term
disability.
Eye infections: irreversible blindness.
CNS infections: meningitis, brain or spinal abscess
formation.
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16. Reduce the incidence of SSI.
Use antibiotics based on evidence of effectiveness
Minimize the effect on the patients normal flora/ the
host defaces
Minimize adverse effects
Use in manner that reduce development of resistance
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17. PROPHYLACTIC ANTIMICROBIAL REGIMENS FOR SURGICAL
PROCEDURES
Considerations in use of prophylactic antimicrobials
during surgery include the following:
1.Selection of antimicrobial agent.
2.Timing of administration.
3.Route of administration.
4.Duration of administration
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18. SELECTION OF ANTIMICROBIAL AGENT
The selection of a prophylactic regimen should incorporate such
factors as:
1.The agent's microbiologic activity against the most likely
potential pathogens encountered during the surgical procedure.
2. Pharmacokinetic characteristics (e.g., half-life);
3. available in a parenteral formulation
4. Inherent toxicity/Minimal potential adverse event
5. Potential to promote the emergence of resistant strains of
bacteria.
6. Cost/ inexpensive

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19. CHOOSING ANTIBIOTICS…
Operations can be separated into two basic categories:
1. Extra-abdominal
Gram positive
Cefazolin
Clindamycin, vancomycin
2. Intra abdominal
Gram negative organisms and anaerobes
Cefoxitin and cefotetan
Fluoroquinolones/aminoglycosides plus clindamycin or
metronidazol

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20. CHOOSING ANTIBIOTICS …
Newer antimicrobials have not demonstrated
superiority in the prevention of SSI and should be
reserved for treatment only.
Carbapenems,
antipseudomonal penicillins, and
third or fourth-generation cephalosporins are not
appropriate antibiotics for surgical prophylaxis.

Overuse of these antibiotics may contribute to
collateral damage and the development of bacterial
resistance
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23. CHOOSING ANTIBIOTICS…
Clean operations (cardiac, orthopedic, vascular)
Cefazolin(1), if has hypersensitivity Vancomycin
Colorectal surgery and appendectomy:
 Anaerobic bacteria: Cefoxitin(2)
Urological surgery
Ciprofloxacin

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24. TIMING OF ANTIMICROBIAL ADMINISTRATION
For maximal efficacy, an antibiotic should be present in
therapeutic concentrations at the incision site
as early as possible during the decisive period and
continuing until the wound is closed.
Because an antibiotic administered postoperatively cannot
achieve therapeutic concentrations during the decisive
period
Such timing of surgical “prophylaxis” is of no benefit in
preventing postoperative wound infections, and infection rates
are similar to those in patients who receive no antibiotics
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25. TIMING OF ANTIMICROBIAL …
Immediately before surgery within 60 min of induction
skin incision for most antibiotics given parentrally
But for vancomycin and ciprofloxacin 2 hours before
skin incision because they need prolonged infusion time
Too early elimination before the end of wound
contamination.
Too late increase incidence of wound infection
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26. ROUTE OF ADMINISTRATION
•Oral administration of surgical antimicrobial
prophylaxis is not recommended because of unreliable
or poor absorption of oral agents in the anesthetized
bowel.
•Oral agents, however, function effectively as GI
decontaminants because high intraluminal drug
concentrations are sufficient to decrease bacterial counts.

•Oral plus parenteral antimicrobial prophylaxis combination
is equivalent or superior to either regimen administered
alone in reducing infection rates
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27. DURATION OF ADMINISTRATION
The shortest effective duration of prophylaxis is desired.
Single-dose prophylaxis is less costly and minimizes the
development of bacterial resistance.
Single-dose prophylaxis also is effective in a variety of GI
tract, orthopedic, and gynecologic procedures.
A single dose of an antibiotic with a short half-life,
however, may provide insufficient antimicrobial coverage
during a prolonged surgical procedure, and repeated
intraoperative dosing or selection of an agent with a
longer half-life is recommended when the duration of
surgery is long
Generally, the duration must not be more than 24 hours
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28. INTRODUCTORY CASE
Now answer the introductory case
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