Antibiotic
Prophylaxis
See also SSI
Principles
1. Target tissue
concentration
- need highest concentration at time of incision and until closure.
- IV administration <1 hr before incision, often at induction
(~30-60m
prior to incision is best)
- if oral, ensure timing is accurate for type.
- there is still small benefit if dose given interoperatively, but
none
afterwards.
2. Cover long procedures
adequately
- if <2hrs, single dose adequate
- additional doses beyond wound closure = no evidence of benefit.
Antibiotics with short half-lives (<2hrs, eg cefazolin,
cefoxitin)
re-dosed every 3-4hrs if prolonged
- final dose may still be given just prior to wound closure.
3. When to use prophylaxis
Usually indicated in clean-contaminated and contaminated operations.
- nb, where operation is 'dirty', antibiotics are being used for
treatment, not prevention.
- clean-contaminated biliary surgery when high risk only (eg
>70yrs,
diabetics, recent instrumentation in biliary tract); vast majority
of
lap choles = no benefit.
Any procedure with high rate of bacteraemia in at-risk pts (eg heart
valves)
Clean surgery is controversial
- indicated in all foreign body implants when infective complication
serious.
- in breast, hernia, RCTs show some evidence for benefit, but
confounded by high risk of infection in control group.
- can argue for use in high-risk pts undergoing relatively clean
surgery (eg gastric)
- or where stress / work delay / reoperation risk would justify it.
4. Administer correctly
If not administered correctly may be harmful instead of beneficial.
- do not use prolonged cover for drains, catheters etc.
- prolongation leads to C dif and increased later noscomial
infections,
as well as drug resistance.
Choice
of Antibiotic
1. Safety
2. Appropriately narrow spectrum
- never a quinolone or 3rd gen cefalosporin
3. Cover Staph aureus
- always cover staph for clean / highrisk celan-contaiminated
surgery
of biliary / upper GI.
- 1st gen cef good choice / clindamycin when history of anaphylaxis
to
penicillins
- vanc where institutional MRSA >20% of all SSIs, god-forbid.
4. Cover most likely microbes to
infect at site.
See below.
Example Regimen
Appendicectomy (anaerobes,
coliforms):
- cefotetan or ceftriaxone
and metronidazole.
- nb not actually prophylaxis; cipro if really needed due to
allergy.
Biliary
- coliforms, enterococci,
anaerobes in obstruction
- coamoxyclav or cephazolin or ceftriaxone.
Cardiovascular
(staph):
- cefamandole
or teicoplanin.
Colorectal
(anaerobes,
coliforms):
- cefotetan or coamoxyclav or cefuroxime and metronidazole.
Gastric malignancy
(coliforms,
anaerobes):
- coamoxyclav or cephazolin and metronidazole.
Gynaecological
(coliforms, anaerobes,
streptococci):
- cefotetan or coamoxyclav.
Orthopaedic hip (staph,
coliforms):
- cephazolin or cefamandole or teicoplanin.
Orthopaedic amputation
(clostridia,
staph, strep):
- coamoxyclav or flucloxacillin +/- metronidazole.
Transplant
(coliforms,
pseudomonads,
staphylococci):
- ciprofloxacin, ceftazidime.
Trauma
Multiple studies unequivocally prove that 24hrs with 2nd gen cef
is all
that is required for penetrating abdo trauma.
- even when shock and colonic injury.
Urological (coliforms):
- coamoxyclav,
gentamicin.
References
Integrated basic surgical sciences.
Barie et al. Surg Clin N Am, 85(2005):1115-35.