| Antibiotic Prophylaxis in Surgery |
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Module 4: VICNISS online self guided surveillance education
To download this module and/or the associated multiple choice exercises as PDF files, click on Education Resources.)
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Overview
This module gives an overview of prevention of surgical site infections specifically via antibiotic prophylaxis in surgery.
Objectives
After you have completed this module you should be able to:
- Explain how surgical site infections can be prevented;
- Understand the recommended doses, duration and timing of antibiotics used for surgical prophylaxis; and
- Understand the recommended prophylaxis regimens for selected operations.
Introduction
Among surgical patients, surgical site infections (SSIs) are the most common nosocomial infection, accounting for 38 percent of nosocomial infections.
It is estimated that SSIs develop in 2 to 5 percent of patients who undergo surgery. The costs of SSIs are substantial, and include patient costs
(morbidity, mortality, lost income), and costs to the hospital system (repeat surgery, increased length of stay, long antibiotic courses).
The goal of antimicrobial prophylaxis is to eradicate or retard the growth of endogenous microorganisms. The efficacy of antibiotic prophylaxis in
clean and clean-contaminated surgery has been clearly established . Most clean surgeries do not require antimicrobial prophylaxis unless there is a
high risk of infection or the consequences of a surgical site infection are disastrous (eg. CABG, insertion of a prosthesis, or laminectomy).
Measures to Reduce Surgical Site Infections
Control measures to reduce SSI rates include:
- Maximising the general health of the patient (optimising nutrition, weight control, blood glucose control, and smoking cessation)
- Meticulous operative techniques (effective hemostasis, removal of devitalised tissues, obliteration of dead space, use of closed suction drains,
and wound closure without tension)
- Timely administration of preoperative antibiotics
Recent data suggests that attention to intraoperative temperature control, and supplemental oxygen administration along with aggressive fluid resuscitation may reduce infection rates.
The use of barrier devices (masks, caps, gowns, drapes, and shoe covers) to prevent SSIs is not supported by rigorously controlled and valid clinical studies. The primary role for these barrier devices is to protect operating room personnel from exposure to infectious blood or body fluids.
A number of practices (such as preoperative showering of the patient, and barrier devices for staff) have been tried over
the years in an effort to both decontaminate patients and to reduce contact between the operative field and flora from
hospital personnel. However, most surgical site infections are caused by microorganisms which already colonise the
patient, and therefore the major source of SSIs is not the staff. In addition, modern methods of antisepsis can
reduce, but not eliminate, the skin-associated bacteria of the surgical patient; approximately 20 percent of the
bacteria are located in hair follicles and sebaceous glands, which are not reached with preoperative antiseptic agents.
Drugs of Choice
First generation cephalosporins (eg. cephazolin) are the drugs of choice for prophylaxis for most clean procedures because of their low incidence of allergy and side effects, antibacterial spectrum, long half-life, and low cost.
For patients with known MRSA colonisation, vancomycin should be considered an appropriate agent for prophylaxis.
Timing of Antibiotic Administration
The timing of intravenous antibiotic administration is important. The relative risk of wound infection is related to the time of antibiotic administration with the optimal time being immediately before the surgical incision. When antibiotics are given more than 2 hours before, the relative risk of infection is 6.7 times higher and when given after the incision is made, the relative risk is 2.4. For these reasons, intravenous antibiotics should be given as close to the time of induction of anaesthesia as possible, but no more than 2 hours before the skin incision is made.
Infusion of the antibiotic should begin within 60 minutes before incision, however, for certain agents which require a longer infusion time (such as vancomycin), the infusion should begin within 120 minutes before the incision.
Dosing & Duration of Antibiotic Prophylaxis
In general, a single dose of a parenteral drug is sufficient. Re-dosing may be required in prolonged procedures, or where there has been significant delay in starting the operation. In these cases, administration should be repeated at 1-2 half-lives after the first dose. For example, cephazolin can be re-dosed after 4 hours.
The practice of continuing antibiotic prophylaxis while surgical drains are in-situ is of unproven benefit. Most studies comparing single-dose prophylaxis with multiple-dose prophylaxis have not shown benefit of additional doses. There are however some examples of surgery where continuing antibiotic prophylaxis is associated with improved outcomes, for example; reduction and internal fixation of traumatic compound fractures.
Antibiotic prophylaxis should be provided in an adequate dose based on patient body weight. For example, cephazolin should be dosed at 2g for patients who weigh in excess of 80 kg.
Anaphylaxis to Beta-Lactam Antibiotics
In the setting of a patient with a history of immediate anaphylaxis to beta-lactam antibiotics (usually penicillin or its derivatives) the recommended alternatives are vancomycin or clindamycin for Gram-positive cover. Examples of other non-beta-lactam antibiotics are; rifampicin, gentamicin,
aztreonam and ciprofloxacin.
Recommended Prophylaxis for Selected Operations:
Different hospitals may have their own prophylaxis protocols, and antibiotic restriction policies. The recommendations below are merely intended as a guide to good practice. These protocols are largely based on Therapeutic Guidelines: Antibiotic (version 12) with some modifications available online:
ANTIBIOTIC PROPHYLAXIS FOR ABDOMINAL SURGERY (COLORECTAL, APPENDICECTOMY, UPPER GIT OR BILIARY, INCLUDING LAPAROSCOPIC):
Prophylaxis is appropriate for all patients undergoing abdominal surgery, even low-risk procedures. The antimicrobial must be active against
Gram-negative bacilli and anaerobes.
A single dose of antibiotic is sufficient, however if the procedure is prolonged beyond 3 hours a second dose of cephazolin or timentin should be
given. Metronidazole may be re-dosed after 4 hours.
- Metronidazole 500mg IV ending infusion prior to induction.
plus
- Cephazolin 1 g IV at the time of induction.
or
- Timentin 3.1 g IV as a single agent.
Metronidazole may be omitted in upper GIT surgery without obstruction or malignancy, and in low-risk biliary surgery.
ANTIBIOTIC PROPHYLAXIS FOR CARDIAC SURGERY:
Most authorities recommend:
- Cephazolin 1g IV at the time of induction.
However, if there is a high endemic rate of Methicillin-resistant Staphylococcus aureus and the duration of hospitalisation pre-operatively is
long, an alternative is:
- Vancomycin 1g IV over at least 1 hour, ending the infusion at the time of induction.
ANTIBIOTIC PROPHYLAXIS FOR CAESAREAN SECTION:
In general, it is recommended that antibiotics be administered after cord clamping. Recommend:
- Cephazolin 1g IV, immediately after clamping the cord.
ANTIBIOTIC PROPHYLAXIS FOR HERNIA REPAIR:
Prophylaxis is not indicated for hernia repair without prosthetic material. In surgery that includes the implantation of mesh the following is
recommended:
- Metronidazole 500mg IV ending infusion prior to induction.
Plus
- Cephazolin 1 g IV at the time of induction.
ANTIBIOTIC PROPHYLAXIS FOR ORTHOPAEDIC SURGERY:
Prophylaxis is required for total joint replacements, and should target the likely pathogens (Staphylococcus aureus, coagulase-negative staphylococci). The following is recommended:
- Cephazolin 1 g IV at induction
or
- Di/flucloxacillin 2 g IV at induction
If a proximal tourniquet is used, the antimicrobial should be completely infused before inflation.
Test your Knowledge - Exercise 1
Clicking the above link will take you to the Education Resources page where you can download a PDF version of the Exercises Questions and Answers
Further Information
References
- E. Patchen Dellinger, Peter A. Gross, Trisha L. Barrett, Peter J. Krause, William J. Martone, John E. McGowan, Jr., Richard L. Sweet, and Richard P. Wenzel. Quality Standards for Antimicrobial Prophylaxis in Surgical Procedures. Clinical Infectious Diseases 1994;18:422-7
- Dale W. Bratzler and Peter M.Houck, for the Surgical Infection Prevention Guidelines Writers Workgroup Antimicrobial Prophylaxis for Surgery: An Advisory Statement from the National Surgical Infection Prevention Project. Clinical Infectious Diseases 2004;38:1706-1715
- Darouiche RO. Antimicrobial approaches for preventing infections associated with surgical implants. Clinical Infectious Diseases 2003; 36(10):1284-9