Chapter 6 - Antibiotic Prophylaxis in Surgery

o The antibiotic must be in the tissue before the bacteria are introduced i.e. antibiotic must be given intravenously shortly before surgery to ensure high blood / tissue levels. Prophylaxis failure may be due to antibiotics given too late or more often, given too early. The half-life of the particular antibiotic is therefore important.

o There is no data to support more than a single dose. Further doses generally constitute treatment. Note the waste of resources, the in-creased risk of complications and the fact that multiple doses are not associated with increased efficiency.

o The chosen antibiotics must be active against the most common ex-pected pathogens.

o Deviations from these guidelines may be warranted in certain situations, e.g. MRSA outbreak in an individual hospital.

o High risk patients, e.g. patients with jaundice or diabetics, or patients who undergo any procedures to insert prosthetic devices, generally warrant antibiotic prophylaxis.

N.B. There are no convincing statistical differences in efficacy between the 1st, 2nd or 3rd generation cephalosporins, therefore a 1st generation cephalosporin MUST be the preferred option.

For which type of operations?

Antibiotic prophylaxis is generally indicated for patients undergoing the following types of operations:

o All clean-contaminated procedures; these include penetration of the gastrointestinal tract, whether by penetrating trauma or related to a pathological organ event (e.g. ruptured appendix, perforated colonic diverticulum) prior to the development of clinical peritonitis.

o Clean operations with foreign body implant (e.g. vascular, cardiac and orthopaedic operations), and those without foreign body implants especially hernia repair, breast surgery, median sternotomy, vascular surgery involving the aorta and the lower extremities, and craniotomy.

The use of antibiotics in operations classified as contaminated or dirty/infected should be considered as therapeutic and is clearly not prophylactic i.e. treatment should be given for a longer duration. Operations for acute cholecystitis, empyema of the gallbladder, ascending cholangitis or liver abscess require antibiotic treatment rather than prophylaxis (see under gastrointestinal infections). The same applies to operations for a perforated appendix with evidence of local or generalised peritonitis and/or intraabdominal abscess, and penetrating abdominal trauma where significant gastrointestinal leakage with peritoneal soiling is identified at the time of the operation.

Timing of antibiotic prophylaxis

Current recommendations are that the parenteral antibiotics used in prophylaxis should be given in sufficient dosage within 30 minutes preceding incision. This results in near maximum drug levels in the wound and the surrounding tissues during the operation. This can be facilitated by having the anaesthetist administer the antibiotic in the operating room when the intravenous lines are inserted shortly before operative incision. A single preoperative dose of antibiotic has the same efficacy as multiple doses and the current recommendation is to administer a second dose only if the operation lasts for longer than 2 - 3 hours. With the oral preoperative antibiotic preparation commonly used before elective colonic resection, the chosen agents should be given during the 24 hours before the operation in order to attain significant intraluminal (local) and serum (systemic) levels.

Route of administration of prophylactic antibiotics

Intravenous administration of the prophylactic antibiotic is preferred for most patients undergoing an operative procedure. Oral antibiotics currently play a major role only in the preparation of patients before elective colon surgery.

Antibiotic prophylaxis for common surgical operations

Antibiotic prophylaxis in cardiovascular surgery has proven beneficial only in the following procedures :

Cardiac: prosthetic valve insertion, coronary artery bypass graft, other open heart surgery, pacemaker implant, median sternotomy.

Note: (i) During prolonged operations, additional intraoperative doses every 4 - 8 hours are indicated.

(ii) Some authors recommend continuing the antibiotic for up to 48 hours after the procedure (e.g. 1 - 2 g 8 hrly).

(iii) Vancomycin, only if there is a high rate of documented MRSA infections in the unit.

Non-cardiac vascular: e.g. aortic resection, prosthesis, groin incision, lower extremity amputation.

a. Cefazolin 1 g pre-induction. Additional intraoperative doses at 4 - 8 hour intervals during prolonged operations

Note: (i) The value of antibiotics in carotid or brachial artery surgery has not been established, unless prosthetic material is used.

(ii) To cover for Gram-negative coliform bacteria during groin incisions, a 2nd generation cephalosporin can be considered, only if high resistance rates to cefazolin are present in a specific community.

Note: Some authors recommend continuing the antibiotic for up to 48 hrs after the procedure to prevent empyema or pneumonia.

1st generation cephalosporins eg. cefazolin 1 - 2 g pre-operatively. If the operation is longer than 3 hours, give a second dose. Some authors recommend continuing the antibiotic for up to 48 hours after the procedure (e.g. cefazolin 1 - 2 g 8 hrly).

Note: (i) The use of a 2nd generation cephalosporin may be considered in cases of possible Gram-negative bacterial contamination (e.g. hip surgery), but is dictated by high incidence of resistance to the 1st generation cephalosporins.

(ii) Data regarding prophylactic antibiotics in arthroscopic surgery is not available.

(iii) Compound (open) fractures are considered contaminated, so antibiotics are essentially therapeutic in such situations.

Antibiotics are indicated in high risk patients only, i.e. patients with bleeding ulcer, obstructive duodenal ulcer, gastric ulcer, low gastric acidity, decreased GI motility, malignancy or morbid obesity.

Most studies show that achieving adequate drainage will prevent post-procedural cholangitis or sepsis and there is no further benefit from prophylactic antibiotics. With inadequate drainage, antibiotics may be of value. The American Society for GI Endoscopy recommends prophylaxis for known or suspected biliary obstruction. The value of prophylaxis for ERCP is controversial.

Note that cephalosporins are not active against the enterococci, yet are clinically effective as prophylaxis in biliary surgery. With cholangitis, treat as infection, not prophylaxis. High risk patients include those >70 years of age, acute cholecystitis, non-functioning gall-bladder, obstructive jaundice or common duct stones.

Available data is limited, routine use is not recommended. For a mesh implant, give prophylaxis e.g. 1st generation cephalosporin as a single dose.

Recommended approach for preoperative preparation before elective colon surgery and terminal ileal surgery:

o Magnesium sulphate, 30 ml of a 50% solution (15 g) orally at 10h00, 14h00 and 18h00.

o Whole-gut lavage with polyethylene glycol electrolyte solution 1L/h for 2 - 4 hours, or 10% mannitol until diarrhoea effluent is clear.

o Neomycin and erythromycin base, 1 g each orally at 13h00, 14h00 and 23h00. Alternative oral antibiotics include metronidazole plus kanamycin or neomycin.

o for patients with beta-lactam allergy, give metronidazole 500 mg IV and gentamicin 3 mg/kg IV pre-operatively, both as single doses.

For non-elective colorectal surgery, give cefoxitin 1 g IV pre-operatively and then 1 g 8 hourly for 3 doses.

o Cefoxitin 2 g IV pre-op and for up to 3 doses. If perforated, continue for 3 - 5 days.

o For patients with beta-lactam allergy, give metronidazole 500 mg IV pre-operatively or use metronidazole in form of suppository.

o Cefoxitin 2 g IV on admission, continue q.i.d. for 2 - 5 days for intestinal perforation

o Vaginal hysterectomy and emergency caesarian section
1st generation cephalosporin eg. cefazolin 1 - 2 g IV, as a single dose.

o Abdominal hysterectomy, cervical cerclage after 18 weeks, induced abortion with risk factors, (e.g. history of previous PID, multiple partners, young, known gonococcal or chlamydia infections) - antibiotic is probably indicated. 1st generation cephalosporin eg. cefazolin 1 - 2 g IV.

o Prostatectomy
Prophylaxis only in high risk patients viz. uraemia, diabetes, neurological bladder, large residual volume, cardiac disease or previous UTI.

o quinolones as a single oral pre-operative dose e.g. ciprofloxacin 500 mg PO stat or

Note: (i) Dilatation of urethra, endoscopic diagnostic procedures, needle biopsy or lithotripsy with sterile urine: prophylactic antibiotics are not indicated.

(ii) Antimicrobials are not recommended prior to urological procedures in patients with sterile urine.

(iv) Ideally the catheter should be inserted two hours or less, prior to surgery.

(v) If the urine is infected, it is preferable to sterilize it before beginning an elective procedure.

o Tonsillectomy with/without adenoidectomy
Data regarding prophylaxis are not available.

o Major head, neck and oral surgery
If incision is through oral or oropharyngeal mucosa:

Infecting microorganisms usually associated with certain operative procedures and the prophylactic antibiotic recommendation.

Surgical procedure	Predominant infecting microorganism(s)	Recommended agent	Dose	Route
Cardiothoracic	Staphylococci	Cefazolin OR Cefuroxime OR Vancomycin (see text)	1 - 2 g 1.5 g	IV IV
Non-cardiac vascular surgery	Staphylococci	Cefazolin or Cefuroxime	1 - 2 g 1.5 g	IV IV
o Arthroplasty of joints, joint replacement o Open reduction of fractures o Lower limb amputation	Staphylococci	Cefazolin	1- 2 g	IV
Gastroduodenal	Streptococci, coliforms, anaerobic bacteria incl. Bacteroides spp.	Cefazolin	1g	IV
Biliary tract For high risk only: > 70 years Obstructive jaundice Acute cholecystits Acute cholangitis Common duct stone Low risk:	Coliforms, enterococci, anaerobic bacteria incl. Bacteroides, clostridia	Cefazolin or Cefoxitin No prophylaxis	2 g 2 g	IV IV
Colon/small bowel	Coliforms, anaerobic bacteria incl. Bacteroides fragilis	Cefoxitin see text for alteratives.	2g	IV
Appendectomy	Coliforms, anaerobic bacteria incl. Bacteroides fragilis	Cefoxitin	2 g	IV
Penetrating abdominal trauma	Coliforms, anaerobic bacteria incl. Clostridia, Bacteroides fragilis	Cefoxitin	2 g	IV
Vaginal or abdominal hysterectomy	Coliforms, enterococci group B streptococci	Cefazolin	2 g	IV
Caesarian section with high risk e.g. premature rupture of membranes Low risk - elective	as for hysterectomy	Cefazolin or Cefoxitin No prophylaxis	1 g 2 g	IV IV
Abortion	as for hysterectomy	Cefazolin	1 g	IV
Prostatectomy	Coliforms	Ciprofloxacin or gentamicin	500 mg 1,5 mg/kg	PO IV
CNS shunts	Staphylococci	Cefazolin	1 g	IV

Antibiotic Prophylaxis In Surgery

Fundamental principles of Surgical Prophylaxis

For which type of operations?

Timing of antibiotic prophylaxis

Route of administration of prophylactic antibiotics

Antibiotic prophylaxis for common surgical operations