Duration of surgical antibiotic prophylaxis
The World Health Organization1 and Centers for Disease Control and Prevention2 advise, on the basis of meta-analyses, that surgical antibiotic prophylaxis should not be continued postoperatively in any circumstances. However, it is the consensus view of the Antibiotic Expert Groups that the limitations in the evidence base warrant a more nuanced approach.
Large trials show that a single preoperative dose of surgical antibiotic prophylaxis is sufficient to prevent postoperative infection for the vast majority of clean and clean–contaminated procedures, and is as effective as longer courses. Intraoperative redosing may be necessary if:
- after prophylaxis is given, there is a significant delay in starting the operation
- a short-acting antibiotic is used (eg cefoxitin, cefazolin) and more than two half-lives of the drug have elapsed since the previous dose
- there is excessive blood loss during the procedure (eg in adults, 1.5 litres or more).
Suggested intraoperative redosing intervals for antibiotics commonly used for surgical antibiotic prophylaxis (below) gives suggested redosing intervals for antimicrobials recommended for surgical antibiotic prophylaxis in these guidelines. The suggested intervals only apply to patients with normal kidney function. For patients with impaired kidney function, seek expert advice.
For a small minority of procedures identified throughout these guidelines, there are inadequate data to show that a single dose of prophylaxis (with or without intraoperative doses) is as effective as 24 hours of prophylaxis. For these procedures, postoperative doses can be considered but prophylaxis should not continue beyond 24 hours. With the exception of these procedures, postoperative (intravenous or oral) antibiotics do not provide benefit.
Evidence does not support continuing prophylactic antibiotics until surgical drains or intravascular or urinary catheters are removed.
Postoperative antibiotics increase the risk of subsequent infections with resistant pathogens and Clostridioides difficile (formerly known as Clostridium difficile).
|
Antimicrobial |
Redosing interval for patients [NB1] [NB2] |
Drug half-life |
|---|---|---|
|
benzylpenicillin |
1 hour |
0.5 hours |
|
cefoxitin |
2 hours |
0.7 to 1.1 hours |
|
cefazolin |
4 hours |
1.2 to 2.2 hours |
|
clindamycin |
6 hours |
2 to 4 hours |
|
gentamicin |
redosing not required [NB3] |
2 to 3 hours |
|
metronidazole |
12 hours |
6 to 8 hours |
|
teicoplanin |
redosing not required |
several days |
|
vancomycin |
12 hours |
4 to 8 hours |
Note:
NB1: The redosing interval is the time at which a repeat intraoperative dose is required. The interval is measured from the initial preoperative dose, rather than the beginning of the operation. For a specific drug, the redosing interval is approximately equivalent to two half-lives. NB2: The redosing intervals in this table only apply to patients with normal kidney function. For patients with impaired kidney function, seek expert advice. NB3: Despite gentamicin’s short half-life, redosing is not required because of its ‘postantibiotic effect’, whereby bacterial killing continues for many hours after plasma concentration is undetectable. | ||