Antimicrobial Prophylaxis in Surgery Quiz

Antimicrobial Prophylaxis in Surgery

• The primary goal of antimicrobial prophylaxis is to prevent surgical site infections (SSIs).
• SSI is defined as an infection related to an incision occurring within 30 days of surgery, or 90 days if prosthetic material was implanted.
• SSIs develop when a pathogenic organism multiplies in the surgical wound.
• Risk factors for SSI include patient characteristics (age extremes, obesity, tobacco use, malnutrition, prolonged postoperative stay, comorbidities like diabetes, remote infection, ischemia, colonization with microorganisms, immunosuppressive therapy) and operation characteristics (length of surgical scrub, skin antisepsis, preoperative shaving, preoperative skin preparation, inadequate instrument sterilization, foreign material in surgical site, surgical technique, surgical wound class, ASA score, unexpected contamination, operation room ventilation).
• The American Society of Anesthesiologists (ASA) preoperative risk score assesses comorbidities to predict the risk of wound infection.
• An ASA score of 2 or higher is associated with a higher wound infection risk.
• Specific wound classes categorized as Clean, Clean-Contaminated, Contaminated, and Dirty have increasing bacterial contamination risk and potential for postoperative infection.
• The severity of bacterial contamination risk corresponds to various types of wounds.
• Endogenous sources of infection include the patient's own normal flora from the skin, GI tract, and mucous membranes, while exogenous infection stems from the surgical staff's or environment's flora, breaks in aseptic techniques, inadequate hand hygiene, and surgical materials.
• Common SSI pathogens include Staphylococcus aureus (20-30%), coagulase-negative staphylococci (13.7%), enterococcus (11.2%), E. coli (8-9.6%), and others.
• Prophylactic antibiotics aim to reduce the prevalence of postoperative wound infections at the surgical site.
• Prophylactic antibiotics are most effective when administered within 1 hour prior to surgical incision.
• For prolonged procedures or high blood loss, additional intraoperative doses may be necessary.
• Repeat postoperative doses are typically unnecessary except for procedures lasting more than 2-3 hours or when major blood loss occurs.
• Optimizing surgical antibiotic doses depends on procedure type, patient factors, and antibiotic half-life.

Objectives

• Understand the impact of surgical site infections (SSIs).
• Identify different types of wound classifications.
• Clarify risk factors for postoperative surgical site infections.
• Recognize typical pathogens involved in various surgical operations.
• Define antimicrobial prophylaxis' role in preventing surgical site infections.
• Analyze the critical importance of timing, duration, and re-dosing of prophylactic antimicrobial agents.
• Recommend appropriate prophylactic antimicrobial agents based on surgical operations, patient characteristics, and potential risks.

Introduction

• Antibiotics are used clinically for prophylactic, anticipatory, empiric, and directed therapy.
• Prophylactic therapy is administered before contamination or infection to prevent postoperative infections.
• Anticipatory therapy is given in situations where contamination has already occurred, focusing on minimizing post-op infections.
• Empiric therapy is used when pathogen identification isn't available, a non-directed approach.
• Directed therapy is utilized after identifying the pathogen.

Pathogenesis of SSI

• Infection sources are both endogenous (patient's own flora) and exogenous (environmental, surgical personnel).
• Specific infection sources are important (GI tract, skin, mucous membranes).
• Contamination sources need to be addressed with aseptic techniques.

Risk Factors for SSI

• Patient characteristics, including age, obesity, tobacco use, malnutrition, and preexisting conditions, influence susceptibility.
• Operation characteristics, such as surgical duration, technique, wound class, and the presence of foreign materials, affect SSI risk.

Recommendations for Surgical Prophylaxis

• Clean surgeries, involving prosthetic material implantation, typically necessitate prophylactic antibiotics.
• Clean-contaminated surgeries require careful consideration.
• Selected contaminated wound surgeries deserve consideration, but the recommendation for clean/contaiminated cases might be different.
• In dirty surgeries, prophylaxis isn’t generally indicated.

Antibiotic Prophylaxis Goals

• Prophylactic antibiotics aim for infection prevention and reduce morbidity/mortality, healthcare duration and costs, and adverse effects on the patient's microbial flora as well as hospital environment.
• Antimicrobial prophylaxis enhances host defense mechanisms to limit infection.

Benefits and Risks

• Benefits include reducing infection incidence and related costs, improving patient outcomes.
• Risks include toxic reactions, allergic reactions, drug interactions, and emerging resistant bacteria.

Principles of Surgical Antimicrobial Prophylaxis

• Employ antibiotics when infection risk is high or complications are severe.
• Target pathogens anticipated to cause infections effectively.
• Administer sufficient antibiotic doses for local tissue adequacy.
• Minimizing side effects and cost-effectiveness are essential.
• Antibiotics shouldn’t negatively affect patient or hospital microbial flora.

Specific Cases

• Cardiothoracic surgery requires specific recommendations for prophylaxis duration.