Colorectal surgery

General Principles of Prescribing Antibiotics for Surgical Prophylaxis

Timing. Antibiotics should be administered or infusion completed within 60 minutes before the procedure or skin incision
Document doses in the "once only" section of the paper drug administration chart (the kardex) or as STAT orders on HEPMA
A single dose of antibiotic is recommended. Exceptions are outlined in individual protocols
No dose adjustment in renal or hepatic impairment is required unless indicated
Repeat dosing may be required if the operation is prolonged (see table below for re-dosing guidance for individual antibiotics):
- The repeat dose is given at the recommended interval from the time the initial dose was administered
- Intra-operative blood loss>1.5L. Re-dose following fluid replacement/blood transfusion
Discuss patients with consultant microbiologist pre-operatively for complex issues including:
- Carriage of or previous infection with resistant organisms, other than MRSA
- Where eGFR is <20ml/min
MRSA. See intranet for MRSA infection control policy on decolonisation prior to surgery.

Antimicrobial recommendations

Procedure	Recommended	Penicillin allergy or MRSA
Colorectal surgery	Gentamicin IV (dose as per table)	Gentamicin IV (dose as per table)
	AND	AND
	Metronidazole 500mg IV	Metronidazole 500mg IV
	AND	AND
	Amoxicillin 1g IV	Teicoplanin 400mg IV

Height is used to estimate ideal body weight, dosing equates to approximately 3mg/kg capped at 300mg.

* When height <5 foot use actual body weight to calculate gentamicin dose.

Antibiotic	Administration	Re-dosing advice: prolonged surgery	Re-dosing advice: >1.5L blood loss
Amoxicillin IV	Bolus over 3-5 minutes	Repeat original dose (every) 4 hours	Repeat original dose
Gentamicin IV	Bolus over 3-5 minutes	Repeat original dose 8 hours after initial dose if eGFR >60ml/min	Give 50% original dose
Metronidazole IV	Infuse over 20 minutes	Repeat original dose after 8 hours	Repeat original dose
Teicoplanin IV	Bolus over 3-5 minutes	No re-dosing required	200mg (50% original dose), if ≥ 1.5L blood loss within first hour of operation