Infectious Disease I: Antimicrobial Prophylaxis in Surgery Courses in Therapeutics and Disease State Management

Learning Objectives (Slide 1 of 2) Differentiate between prophylactic, presumptive, and therapeutic antibiotics in the perioperative patient. Identify patient-specific risk factors for surgical site infections (SSIs). Identify procedure-specific risk factors for SSIs. List common pathogens responsible for SSIs. Explain the importance of timing of antimicrobial prophylaxis for surgery. Choose an evidence-based prophylactic antimicrobial regimen for specific types of surgeries.

Learning Objectives (Slide 2 of 2) Individualize prophylactic antimicrobial regimens by considering the type of surgery, intrinsic patient risk factors, and knowledge of common pathogenic organisms. Recommend an alternative prophylactic antimicrobial regimen for patients with life-threatening allergies to first-line therapies. Identify clinical scenarios where multiple dose regimens of prophylactic antimicrobials are appropriate as compared to single dose regimens. List nonpharmacological interventions effective at reducing the risk of postoperative SSIs.

Required and Recommended Reading Required Reading Kanji S. Chapter 101. Antimicrobial Prophylaxis in Surgery. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L. eds. Pharmacotherapy: A Pathophysiologic Approach, 9e. New York, NY: McGraw-Hill; 2014. Recommended Readings Bratzler DW, Dellinger EP, Olsen KM, et al. Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J Health Syst Pharm 2013;70:195-283.

Overview of Surgical Site Infections Surgical site infections (SSI) are a common cause of nosocomial infections and lead to increased costs and prolonged hospitalization Prophylactic administration of antibiotics lowers the risk of a surgical site infection Prevents the contamination of sterile tissues or fluids during surgery Timing of antibiotics is important to ensure the antibiotic is at a peak concentration at the time of the incision Infections acquired from surgical procedures and non-surgery related issues are termed nosocomial infections Presumptive antibiotic therapy is administered to patients where an infection is suspected Patients with acute appendicitis, compound fractures, or acute cholecystitis are presumed to have an infection until proven otherwise If no infection is found, the patient will be placed on appropriate prophylactic therapy

SSI Categories Incisional: Occurs at the site of surgical incision Superficial: Skin or subcutaneous tissue Deep: fascial and muscle layers Organ/space: Can occur in any anatomic site other than the surgical incision site

Surgical Site Infection Risk Factors Risk of SSI depends on both surgical procedure and patient specific factors National Research Council has developed a SSI risk classification system

National Research Council Wound Classification, Risk of Surgical Site Infection, and Indication for Antibiotics SSI Rate (%) Classification Preoperative Antibiotics No Preoperative Antibiotics Criteria Antibiotics Clean 5.1 0.8 No acute inflammation or transection of GI, oropharyngeal, genitourinary, biliary, or respiratory tracts; elective case, no technique break Not indicated unless high-risk procedurea Clean–contaminated 10.1 1.3 Controlled opening of aforementioned tracts with minimal spillage/minor technique break; clean procedures performed emergently or with major technique breaks Prophylactic antibiotics indicated Contaminated 21.9 10.2 Acute, nonpurulent inflammation present; major spillage/technique break during clean–contaminated procedure Dirty N/A Obvious preexisting infection present (abscess, pus, or necrotic tissue present) Therapeutic antibiotics required From AccessPharmacy: accesspharmacy.mhmedical.com, Copyright© McGraw-Hill Education. All rights reserved. Chapter 101. Antimicrobial Prophylaxis in Surgery, Table 101-1 Pharmacotherapy: A Pathophysiologic Approach, 9e, 2014 Joseph T. DiPiro, Robert L. Talbert, Gary C. Yee, Gary R. Matzke, Barbara G. Wells, L. Michael Posey N/A, not applicable; SSI, surgical site infection.  aHigh-risk procedures include implantation of prosthetic materials and other procedures where surgical site infection is associated with high morbidity (see the text). Adapted from references 5 and 11.

Surgical Site Infection Risk Factors (cont.) Patient specific factors must be taken into account when initiation prophylactic antibiotics prior to a surgical procedure Patient Operation Age Duration of surgical scrub Nutritional status Preoperative skin preparation Diabetes Preoperative shaving Smoking Duration of operation Obesity Antimicrobial prophylaxis Coexisting infections at distal body sites Operating room ventilation Colonization with resistant microorganisms Sterilization of instruments Altered immune response Implantation of prosthetic materials Length of preoperative stay Surgical drains Surgical technique Reprinted with permission from Elsevier and the Association for Professionals in Infection Control and Epidemiology. Original table citation: Mangram AJ, Horan TC, Pearson ML, et al. Guideline for prevention of surgical site infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27:97–132.  [PubMed: 10196487]  Reprinted as Table 101-2 Patient and Operation Characteristics That May Influence the Risk of Surgical Site Infection Pharmacotherapy: A Pathophysiologic Approach, 9e, 2014 Joseph T. DiPiro, Robert L. Talbert, Gary C. Yee, Gary R. Matzke, Barbara G. Wells, L. Michael Posey

Common Bacteria by Surgical Site Organisms causing SSI originate from two main areas Endogenously (i.e. normal flora) Translocation of Staphylococcus aureus on the skin into the sternum during open heart surgery Exogenously (i.e. contamination during the surgical procedure) Perforation of the bowel during an appendectomy causing an acute peritonitis Antimicrobial Resistance Patients may become colonized with multi drug resistance bacteria Prolonged inpatient stay prior to surgery Fomite transmission Contact with health care providers working in an inpatient setting Institution antibiograms will aid in the identification of resistance patterns and selection of prophylactic antibiotics

Antimicrobial Selection (Slide 1 of 2) Factors to consider Classification of surgical procedure and the most common pathogens associated with this procedure Antimicrobial Specific Factors Safety and efficacy Current literature evidence supporting its use Cost Patient Specific Factors Normal flora/ colonization with multi drug resistant pathogens Allergies Drug-drug interactions Institutional susceptibility patterns of nosocomial pathogens

Antimicrobial Selection (Slide 2 of 2) General consideration Clean surgical procedures such as vascular, orthopedic, neurosurgery, cardiac, etc. utilize cefazolin as the first line prophylactic antibiotic Cefazolin covers normal skin flora (Staphylococcus sp. and Streptococci sp) Cefazolin has a narrow spectrum of coverage Vancomycin is used second line in patients with allergies to β-lactam agents who cannot take cefazolin Clindamycin is used third line after the cephalosporins and vancomycin, but does provided additional anaerobic coverage Clean-contaminated surgical procedures such as appendectomy, high risk GI surgery, or whenever the operation will transect a hollow viscous or mucous membrane that may contain resident flora require enteric gram negative bacilli and anaerobic coverage 2nd Generation Cephalosporins with anaerobic coverage are normally the drugs of first choice Cefoxitin Cefotetan Combinations of agents that cover for gram negative bacilli and anaerobes may utilized Cefazolin plus metronidazole Vancomycin plus metronidazole Clindamycin plus aminoglycosides Metronidazole plus aminoglycosides Aztreonam plus metronidazole

Most Likely Pathogens and Specific Recommendations for Surgical Prophylaxis Link: Table featuring Most Likely Pathogens and Specific Recommendations for Surgical Prophylaxis

Summary Identify the risk factors for the Surgical Site Infection (SSI) Surgery type Most likely pathogens Select prophylactic antimicrobial therapy Patient factors Medication factors Local resistance Monitoring signs and symptoms of SSI

References Kanji S. Chapter 101. Antimicrobial Prophylaxis in Surgery. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L. eds. Pharmacotherapy: A Pathophysiologic Approach, 9e. New York, NY: McGraw-Hill; 2014. Bratzler DW, Dellinger EP, Olsen KM, et al. Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J Health Syst Pharm 2013;70:195-283.