Antimicrobial Prophylaxis for Surgery Flashcards
Surgical Site Infections
nfection related to incision occurring within 30
days of operative procedure or within 90 days if prosthetic material
implanted
• May result in prolonged rehabilitation, pain, and antibacterial
resistance
• Health care costs associated with SSI can be very high, and especially so
when involving a prosthetic joint implant
Surgical Site Infections
- Infection is most common complication of surgery
- SSI is 3rd most common cause of nosocomial infections (14-16%)
- Prolong hospitalization by average of 7 days
Sources of Infection
• Environment
• Surgeon, surgical team
• Patient skin, mucous membranes
• Usually Gram-positive cocci (staphylococci)
• Patient internal organs (if penetrated)
• e.g., Gram-negative aerobes and anaerobic bacteria
if incision in GI tract or GU tract or perineum
Risk Factors for Surgical Site Infections
staph aureus is common (particul. MRSA)
cigs - impaired wound healing,
Coincident remote site infections or colonization Diabetes Cigarette smoking Systemic steroid use or other immunosuppressants Obesity Extremes of age Malnutrition Perioperative transfusion Degree of immunocompromise
improper use of abx prophylaxis (dose, timing, wrong agent)
perioperative hypoxia, hypothermia
Prevention
• Sterile ORs with positive pressure • Surgeon preoperative gown/cap/shoe covers and hand/forearm asepsis/gloves. • Strict aseptic technique • Educated OR staff • Policies and procedures • Quality assurance
patient preparation
• Treatment of pre-existing infections
(e.g., UTI before prostate surgery)
• Shower with soap or antiseptic (chlorhexidine) at
least night before surgery
• Adequate skin-preparation
• Hair clipping rather than shaving (or no clipping)
• Povidone-iodine (Betadine), alcohol,
chlorhexidine gluconate (Hibitane)
• Skin prepped in concentric circles (clean to dirty)
• Antibacterial prophylaxis as indicated
• Mupirocin for carriers of S. aureus ?
Antibacterial Prophylaxis
• Very brief course of antimicrobial agent just before
surgery begins
• Timing important – it is important to have adequate drug
concentrations at the time of surgery and throughout
the surgery
• Goal not to sterilize tissues and not to cover all possible
microorganisms, but to reduce microbial burden to level
that cannot overwhelm host defenses
Principles of Antibacterial Prophylaxis
- Use an agent shown to reduce SSIs for that
particular type of surgery - Use an agent that is safe, inexpensive, and
bactericidal with a spectrum that covers most
probable contaminants - Time the infusion so that bactericidal concentration of
drug is established in serum and tissues by the time
skin incised - Maintain therapeutic levels in serum and tissues
until at most a few hrs after incision closed
Probability of Infection with
Prophylactic Antibacterials
Reduction in risk of fever with prophylactic antibiotics
for a given bacterial burden
Timing of Prophylactic Antibacterials
RAPE (Trial to Reduce Antibiotic Prophylactic Errors)
found SSI risk lowest if cephalosporins
given within 30 minutes (Vancomycin or a
fluoroquinolone within 1 hour.)
• Administer antibacterial only when indicated
• The optimal timing of administration of prophylactic
antibacterials is within 60 minutes before the surgical
procedure for most antibacterials
• Fluoroquinolones and vancomycin require prolonged
infusion times
• Infusion should begin within 2 hours of the
incision
• Administer prophylactic antibacterials before skin
incision in all cesarian section procedures.
Surgical Wound Classification
class 1 to 2
Class I – Clean
• An uninfected wound with no inflammation and the
respiratory, alimentary, genital, or uninfected
urinary tract is not entered
• Primary closure or closed drainage
• No break in aseptic technique
Class II – Clean-Contaminated
• respiratory, alimentary, genital, or uninfected
urinary tract are entered under controlled
circumstances without unusual contamination
• (e.g., biliary tract, appendix, vagina, oropharynx
provided no infection or break in technique)
Surgical Wound Classification
class 3 to 4
Class III – Contaminated
• Open, fresh, accidental wounds, ruptured bowel
• Operations with major break in technique
e.g., spillage from GI tract, open cardiac massage
Class IV – Dirty/Infected
• Old traumatic wounds with retained devitalized tissue,
existing clinical infection, or perforated viscera
• Obvious preexisting infections present (abscess, pus,
or necrotic tissue present)
• (organisms present in operative field before surgery)
Choice of Antibacteria
wich cephalosporin
• Cefazolin widely used
• (clindamycin or vancomycin chosen if serious cefazolin allergy)
• Surgery on distal GI tract requires agent that provides
anaerobic coverage including B. fragilis (e.g., cefoxitin
or [cefazolin + metronidazole])
• Alternative gentamicin + metronidazole (or gentamicin
+ clindamycin)
• 3rd or 4th generation cephalosporins not routinely
recommended for prophylaxis
Routine use of Vancomycin is not routinely
recommended for any procedure
when should it be used then?
• May be choice if high incidence of MRSA or MRSE postoperative infections
• May be chosen in severe cefazolin allergy
(or severe non-IgE-mediated reaction to a β-lactam)
• Should be chosen for patients with known MRSA colonization or
at high risk for MRSA from surveillance data (e.g., recent hospitalization, hemodialysis)
• Vancomycin is less effective in preventing SSIs due to MSSA
– at some institutions cefazolin will be used in combination with vancomycin
Cephalosporins exhibit time-dependent PD
• Ideal to maintain levels > MIC for target pathogens for
duration of operation
• When duration of surgery ______________ an
additional dose is given (e.g., t1/2 2 hours for cefazolin)
exceeds 2 times the t1/2
• Vancomycin, fluoroquinolones require prolonged
infusion times and infusion should begin within 2 hr of
incision
• “on-call to O.R.” infusion not recommended due to
time delays
