Note: SIGN 104 Antibiotic Prophylaxis in Surgery is currently under review.  Update of this section is awaiting publication of these national recommendations, due in 2025.
  • Prophylaxis should be started pre-operatively, ideally within 30 to 60 minutes before skin incision.
  • The antibiotics selected for prophylaxis must cover the common or suspected pathogens, eg adding teicoplanin if MRSA suspected or known MRSA carrier.  See appended dosing table for teicoplanin (based on 6mg/kg actual bodyweight, rounded to nearest 200mg).  Note: many MRSA isolates in NHS Highland are sensitive to gentamicin.
  • Gentamicin doses are based on 3mg/kg ideal body weight (derived from height).  A dosage table is appended.  AVOID gentamicin if eGFR <10mL/min or on dialysis: seek advice from Microbiology.
  • Patients with a history of anaphylaxis or urticaria or rash occurring immediately after penicillin therapy are at increased risk of immediate hypersensitivity to penicillins and should not receive prophylaxis with a beta-lactam antibiotic.
  • An additional dose of prophylactic agent is not indicated in adults, unless there is blood loss of greater than 1500mL during surgery or surgery is prolonged.  See table below for advice for specific drugs. 
  • Always record prophylaxis in the “once only” section of the drug chart.

Category of surgery 


Antibiotics (single intravenous dose unless stated) 

Comment and alternatives for beta-lactam hypersensitivity

Cardiothoracic surgery

Cardiac pacemaker insertion

Teicoplanin (dose as table) 

ENT surgery 

Head and neck surgery – contaminated/clean contaminated only

Flucloxacillin 1 gram 
Metronidazole 500mg

Teicoplanin (dose as table)
Metronidazole 500mg

Grommet insertion

Topical Sofradex: 3 drops into each ear post-procedure

Orthopaedic surgery 

Procedures involving prosthetic material
Closed fracture fixation
Hip fracture repair
Spinal surgery 

Teicoplanin (dose as table)

 If teicoplanin unsuitable, contact Microbiology for alternative

Open fracture (upper/lower limb)

Hand trauma (dirty/open fractures)

Contaminated/dirty lacerations

Co-amoxiclav 1·2g every 8 hours

Clindamycin 600mg every 6 hours

Give antibiotics as soon as possible after the injury. Continue until soft tissue closure or a maximum of 72 hours, whichever is sooner

General surgery   

Hepatobiliary surgery

Gentamicin (dose as table) PLUS metronidazole 500mg

Gentamicin (dose as table) PLUS metronidazole 500mg


Gentamicin (dose as table)

If gentamicin unsuitable - aztreonam 1 gram

Colorectal surgery
Small bowel surgery
Gastroduodenal surgery
Oesophageal surgery

Gentamicin (dose as table) PLUS metronidazole 500mg PLUS amoxicillin 1 gram

Gentamicin (dose as table)
PLUS metronidazole 500mg PLUS teicoplanin (dose as table) 

Colorectal EUA +/- haemorrhoidectomy

CONSIDER metronidazole 500mg

Breast surgery

Co-amoxiclav 1·2 grams

Clarithromycin 500mg

Endoscopic gastrostomy

Co-amoxiclav 1·2 grams

Teicoplanin (dose as table) 

Obstetrics and gynaecology   

Caesarean section (dose at induction of anaesthesia)

Co-amoxiclav 1·2 grams

Metronidazole 500mg 
PLUS EITHER cefuroxime 1·5 grams OR if beta-lactam anaphylaxis
teicoplanin (dose as per table based on booking weight) 

If patient has BMI over 35 at booking or most recent weight is 100kg or more

Co-amoxiclav 1·2 grams PLUS amoxicillin 1 gram

Manual removal of placenta
Repair of obstetric anal sphincter injury (3rd/4th degree tear)

Co-amoxiclav 1·2 grams 

Gentamicin (dose as table) PLUS metronidazole 500mg

Surgical termination of pregnancy

Oral metronidazole 400mg

Refer to departmental guidelines 

For women who screen positive for chlamydia or no result

PLUS oral azithromycin 1 gram
See Genital Tract Infections section


Adrenalectomy (open/lap)

Not recommended


Botulinum injections

Trimethoprim 200mg oral

Check if known pathogen


Not recommended   




Check if known pathogen

Cystoscopy + biopsy/distension

Not recommended  

Check if known pathogen


Gentamicin + metronidazole


Ileal Conduit

Gentamicin + metronidazole 


Inguinal (any)

Not recommended


Nephrectomy (open/lap)

Not recommended


Partial Nephrectomy

Not recommended 


Penile (any)

Not recommended




Check if known pathogen

Prostate biopsies

Ciprofloxacin 1g oral and/or gentamicin (see BNF warnings and MHRA Drug Safety Alert (updated 22 January 2024))

Gentamicin if treated with ciprofloxacin within last 6 months




Scrotal (any)

Not recommended


Stent insertion



Suprapubic catheter


Check if known pathogen

Testicular prosthesis insertion

Gentamicin + flucloxacillin



Not recommended

Check if known pathogen



Check if known pathogen

Ureteroscopy (stone/diagnostic)


Check if known pathogen



Check if known pathogen

Vascular surgery 

Elective admission screened and MRSA-negative

Flucloxacillin 1 gram PLUS gentamicin (dose as table)


Emergency admissions, MRSA-positive or penicillin allergy


Teicoplanin (dose as table) PLUS gentamicin (dose as table)

Prevention of gas gangrene in amputations or following major trauma

Metronidazole 500mg intravenously every 8 hours for 5 days


For glossary of terms see Glossary.

Gentamicin dosing table for surgical prophylaxis

 Height range  Gentamicin dose for prophylaxis 
 Feet & inches Metres Male Female
 4’8” to 4’10”  1·42m to 1·47m 160mg 140mg
 4’11” to 5’3”  1·48m to 1·60m 180mg 160mg
 5’4” to 5’10”  1·61m to 1·78m 240mg 200mg
 5’11” and taller  1·79m and taller 300mg 260mg

AVOID gentamicin if eGFR <10mL/min or on dialysis: seek advice from Microbiology

  • Doses of up to 300mg can be given as a bolus injection over 3 to 5 minutes but it is recommended that higher doses are administered as a short infusion.
  • A single dose of gentamicin will provide cover for 8 hours in patients with normal renal function and will not result in toxicity even in patients with impaired renal function.

Teicoplanin dosing table for surgical prophylaxis

 Actual bodyweight Teicoplanin dose
(based on 6mg/kg and rounded to nearest 200mg)
 35kg to 65kg 400mg
66kg to 99kg 600mg
100kg to 130kg 800mg
131kg to 166kg 1000mg
167kg to 200kg 1200mg
  • Seek advice if patient weighs more than 200kg or is on renal dialysis
  • No dose adjustment is necessary in renal impairment for a single dose of teicoplanin.
  • All doses should be given as a bolus injection over 3 to 5 minutes.

Re-dosing advice: long procedures/extensive blood loss

Drug & dose Procedure duration  Blood loss above 1500mL
(give after fluid replacement)
Over 4 hours Over 8 hours
Gentamicin 3mg/kg - Repeat dose Give half original dose
Metronidazole 500mg - Repeat dose  Repeat dose
Teicoplanin 6mg/kg - - Give half original dose
Amoxicillin 1g Repeat dose Repeat dose Repeat dose
Cefuroxime 1·5g Give 750mg Give 750mg Repeat dose
Co-amoxiclav 1·2g Repeat dose Repeat dose Repeat dose
Flucloxacillin 1g Repeat dose Repeat dose Repeat dose


Editorial Information

Last reviewed: 07/11/2019

Next review date: 07/11/2022

Author(s): Antimicrobial Management Team.

Version: 11.1

Approved By: TAM subgroup of ADTC

Reviewer name(s): Alison Macdonald, Area Antimicrobial Pharmacist.

Document Id: AMT173