Mary A. Ullman, Jeremy A. Schafer, and John C. Rotschafer
LEARNING OBJECTIVES
Upon completion of the chapter, the reader will be able to:
1. Discuss the epidemiology and impact of surgical wound infections on patient outcomes and health care costs.
2. Name and differentiate the four different types of wound classifications.
3. Recognize at least three risk factors for postoperative surgical site infections (SSIs).
4. Identify likely pathogens associated with different surgical operations.
5. Compare and contrast antimicrobials used for surgical prophylaxis and identify potential advantages and disadvantages for each antibiotic.
6. Discuss the importance of β-lactam allergy screening and how this could impact resistance and health care costs.
7. Identify nonantimicrobial methods that can reduce the risk of postoperative infection.
8. Discuss the possible impact of antimicrobial-impregnated bone cement and how this affects the use of antimicrobial prophylaxis in surgery.
9. Discuss the importance of timing, duration, and redosing in relation to antimicrobial prophylaxis in surgery.
10. Recommend appropriate prophylactic antimicrobial(s) given a surgical operation.
KEY CONCEPTS
Surgical site infections (SSIs) are a significant cause of morbidity and mortality.
The distinction between prophylaxis and treatment influences the choice of antimicrobial and duration of therapy.
Surgical operations are classified as clean, clean-contaminated, contaminated, or dirty.
Choosing the appropriate prophylactic antimicrobial relies on anticipating which organisms are likely to be encountered during the operation.
A thorough drug allergy history should be taken to discern true allergy (anaphylaxis) from other adverse events (stomach upset).
Further study is needed before antibiotic-impregnated bone cements can be recommended as an alternative to preoperative prophylaxis with traditional antimicrobials for orthopedic operations.
For prevention of SSIs, correct timing of antimicrobial administration is imperative so as to allow the persistence of therapeutic concentrations in the blood and wound tissues during the entire course of the operation.
The goal of antimicrobial dosing for surgical prophylaxis is to optimize the pharmacodynamic parameter of the selected agent against the suspected organism for the duration of the operation.
The duration of antimicrobial prophylaxis should not exceed 24 hours (48 hours for cardiac surgery); additional doses of antimicrobial past this time point do not demonstrate added benefits.
According to Centers for Disease Control and Prevention criteria, SSI may appear up to 30 days after an operation and up to 1 year if a prosthesis is implanted.
Surgical site infections (SSIs) are a significant cause of morbidity and mortality. Approximately 2% to 5% of patients undergoing clean extra-abdominal operations and 20% undergoing intra-abdominaloperations will develop an SSI.1 SSIs have become the second most common cause of nosocomial infection and these data are likely underestimated.1 More than 70% of surgical procedures are now performed on an outpatient basis, creating a significant potential for under-reporting.2
SSIs negatively affect patient outcomes and increase health care costs. Patients who develop SSIs are five times more likely to be readmitted to the hospital and have twice the mortality of patients who do not develop an SSI.1 A patient with an SSI is also 60% more likely to be admitted to an ICU.1 SSIs increase lengths of hospital stay and costs.1,3,4 The type of SSI can also affect the severity of a patient’s negative outcome due to surgery. Deep SSIs, involving organs or spaces, result in longer durations of hospital stay and higher costs compared to SSIs that are limited to the incision.5 Additionally, beginning in 2008, Medicare and Medicaid Services will no longer reimburse the hospitals for any cost incurred from treating certain hospital-acquired infections, including SSIs.6 Thus, even greater importance is placed on preventing infection, and, if infection should occur, treatment of the infection should be for the shortest duration possible and in the most cost effective manner.
SSIs are defined and reported according to Centers for Disease Control and Prevention (CDC) criteria.5 SSIs are classified as either incisional or organ/space. Incisional SSIs are further divided into superficial incisional SSI (skin or subcutaneous tissue) and deep incisional SSI (deeper soft tissues of the incision). Organ/space SSIs involve any anatomic site other than the incised areas. For example, a patient who develops meningitis after removal of a brain tumor could be classified as having an organ/space SSI. An infection is considered as SSI if any of the above criteria is met and the infection occurs within 30 days of the operation. If a prosthetic is implanted, the timeline extends out to 1 year.
EPIDEMIOLOGY AND ETIOLOGY
Numerous risk factors for SSI have been identified in the literature.5,7,8 These factors can be divided into two categories: patient and operative characteristics. Patient risk factors for SSI include: age, comorbid disease states (especially chronic lung disease and diabetes), malnutrition, immunosuppression, nicotine or steroid use, and colonization of the nares with Staphylococcus aureus. Many patients developing postoperative wound infections bring the organism with them into the hospital. Modifying risk factors may decrease the threat of SSI. Malnutrition can be corrected using enteral or parenteral feedings. Additional nonantimicrobial strategies to reduce SSI will be discussed later.
Operative characteristics are based on the actions of both the patient and the operating staff. Shaving of the surgical site prior to operating can produce microscopic lacerations and increase the chance of SSI and is, therefore, not accepted as a method of hair removal.5 Maintaining aseptic technique and proper sterilization of medical equipment is effective in preventing SSI. Surgical staff should wash their hands thoroughly. In clean surgeries, most bacterial inoculums introduced postoperatively are generally small. However, subsequent patient contact between contaminated areas (nares or rectum) and the surgical site can lead to SSI. Finally, the appropriate use of antimicrobial prophylaxis can have a significant impact on decreasing SSIs.
PATHOPHYSIOLOGY
Prophylaxis Versus Treatment
Properly identifying the state of an infection is important when using antimicrobial prophylaxis in surgery. Antibiotic prophylaxis begins with the premise that no infection exists but that during surgery there can be a low level inoculum of bacteria introduced into the body. However, if sufficient antimicrobial concentrations are present, the situation can be controlled without infection developing. This is the case when surgery is done under controlled conditions, there are no major breaks in sterile technique or spillage of GI contents, and perforation or damage to the surgical site is absent. An example would be an elective hysterectomy done with optimal surgical technique.
If an infection is already present, or presumed to be present, then antimicrobial use is for treatment, not prophylaxis, and the goal is to eliminate the infection. This is the case when there is spillage of GI contents, gross damage or perforation is already present, or the tissue being operated on is actively infected (pus is present and cultures are positive). An example would be a patient undergoing surgery for a ruptured appendix with diffuse peritonitis.
The distinction between prophylaxis and treatment influences the choice of antimicrobial and duration of therapy. Appropriate antimicrobial selection, dosing, and duration of therapy differ significantly between these two situations. A regimen for antimicrobial prophylaxis ideally involves one agent and lasts less than 24 hours. Treatment regimens can involve multiple antimicrobials with durations lasting weeks to months depending on desired antimicrobial coverage and the surgical site.
Types of Surgical Operations
Surgical operations are classified at the time of operation as clean, clean-contaminated, contaminated, or dirty. Antimicrobial prophylaxis is appropriate for clean, clean-contaminated, and contaminated operations. Dirty operations take place in situations of existing infection and antimicrobials are used for treatment, not prophylaxis (Table 85–1).
Microbiology
Choosing the appropriate prophylactic antimicrobial relies on anticipating which organisms will be encountered during the operation. SSIs associated with extra-abdominal operations are the result of skin flora organisms in nearly all cases. These organisms include gram-positive cocci, with S. aureus and Staphylococcus epidermidis being among the most frequently isolated SSI pathogens according to the National Nosocomial Infections Surveillance System (NNIS)5 (Table 85–2). Streptococcus spp. and other gram-positive aerobes may also be implicated.
Table 85–1 National Red Cross Wound Classification, Risk of SSI, and Antibiotic Indication
Intra-abdominal operations involve a diverse flora with the potential for polymicrobial SSIs. Escherichia coli make up a large portion of bowel flora and are frequently isolated as pathogensaccording to the NNIS.5 Other entericgram-negative bacteria, as well as anaerobes (especially Bacteroides spp.), may be encountered during intra-abdominal operations.
Candida albicans is being implicated as the cause of a growing number of SSIs. According to the NNIS, from 1991 to 1995, the incidence of fungal SSIs rose from 0.1 to 0.3 per 1,000 discharges.5 Increased use of broad-spectrum antimicrobials and rising prevalence of immunocompromised and human immunodeficiency virus-infected individuals are factors in fungal SSIs. Despite this increase, antifungal prophylaxis for surgery is not currently recommended.
Choosing an Antibiotic
An antimicrobial used in surgical prophylaxis should meet certain criteria. Selecting an antimicrobial with a spectrum that covers expected pathogens is crucial. The antimicrobial should be inexpensive, available in a parenteral formulation, and easy to use. Adverse-event potential should be minimal. Choosing an agent with a longer half-life reduces the likely need to redose unless the surgical procedure is prolonged.
Table 85–2 Major Pathogens in Surgical Wound Infections
Operations can be separated into two basic categories: extra-abdominal and intra-abdominal. SSIs resulting from extra-abdominal operations are frequently caused by gram-positive aerobes. Thus, an antimicrobial with strong gram-positive coverage is useful. Cefazolin benefits from a benign adverse-event profile, simple dosing, and low cost. These aspects have made cefazolin the mainstay for surgical prophylaxis of extra-abdominal procedures. For patients with a β-lactam allergy, clindamycin or vancomycin can be used as an alternative.
Intra-abdominal operations necessitate broad-spectrum coverage of gram-negative organisms and anaerobes. Antianaerobic cephalosporins, cefoxitin and cefotetan, are widely used. Fluoroquinolones or aminoglycosides, paired with clindamycin or metronidazole, should provide adequate coverage for intra-abdominal operations; these regimens are recommended as appropriate regimens for use in patients with β-lactam allergies.
The Hospital Infection Control Practices Advisory Committee allows for the use of vancomycin for surgical prophylaxis when methicillin-resistant Staphylococcus aureus (MRSA) rates at an institution are “high.”1 Unfortunately, a “high” rate of MRSA has not been standardized. Additionally, vancomycin use in institutions where MRSA rates are “high” may not translate into a lower incidence of SSI. Finkelstein and associates found that the incidence of SSI for patients on cefazolin or vancomycin did not differ despite a high MRSA rate at the study institution. However, patients who received cefazolin were more likely to develop an SSI due to MRSA.10 The increasing prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in patients admitted to the hospital creates an added concern, although this pathogen is often sensitive to clindamycin. Vancomycin should be considered appropriate surgical prophylaxis for those patients identified as being colonized with MRSA (prior to or at admission).1
Due to antimicrobial shortages of the recommended antimicrobials and development of newer antimicrobials (e.g., carbapenems, third and fourth generation cephalosporins, and antipseudomonal penicillins), some interest has been generated in the use of these newer antimicrobials for surgical prophylaxis. Recently, ertapenem was determined to be superior to standard cefotetan in the prevention of SSIs after elective colorectal surgery.11 However, the ertapenem treatment group had a larger proportion of Clostridium difficile infections than those in the cefotetan treatment group. Ertapenem has been included as an approved antibiotic for colon surgery by some agencies.12 At this time, it is not considered appropriate to use these newer antimicrobials for surgical prophylaxis; overuse of these antimicrobials may contribute to collateral damage and the development of bacterial resistance. Further research is needed before any of these newer agents are routinely used for surgical prophylaxis. New guidelines are likely to be published soon and may offer guidance on the use of newer antimicrobials.
β-Lactam Allergy
Penicillin allergy is one of the most common reported drug allergies. Concerns over cross-reactivity may limit the use of β-lactams for surgical prophylaxis. A thorough drugallergy history should be taken to discern true allergy (e.g., anaphylaxis) from adverse event (e.g., stomach upset). Allergy testing may be helpful in confirming a patient’s penicillin allergy and could spare vancomycin. However, practitioners should be aware allergy testing may be difficult to perform due to the removal of a major component (penicilloyl- polylisine) of the testing from the commercial market.13 If a practitioner desires to perform allergy testing, the individual reagents required for penicillin allergy testing must be prepared at the health care facility, on a case-by-case basis. Cross-allergenicity between penicillin and cephalosporins is low. The increased risk of cephalosporin allergy in patients with a history of penicillin allergy may be as low as 0.4% for first-generation cephalosporins and nearly zero for second- and third-generation agents.14 Other studies also found the risk of cross-reactivity to be very low.15 However, in the case of severe penicillin allergy (anaphylaxis), cephalosporins should be avoided.
Alternative Methods to Decrease SSI
Several nonantimicrobial methods have been studied for reducing the risk of SSI.16 Providing supplemental warming to patients (36.6°C [98°F]) during the intraoperative period reduced infection rates compared to control patients (34.7°C [94.5°F]).17 Intensive glucose control (maintaining blood glucose to 80 to 110 mg/dL [4.4-6.1 mmol/L]) versus conventional control (blood glucose less than 220 mg/dL [less than 12.2 mmol/L]) reduced infections and improved outcomes in cardiac patients who received intensive insulin control in the ICU after surgery.18 Also, patients randomized to 80% inspired oxygen had lower SSI rates compared to patients on 30% oxygen after colorectal resection.19 Despite these findings, there are insufficient data to make definitive recommendations on the use of these therapies.
Antimicrobial-impregnated bone cement is being used as an adjunct or alternative to traditional antimicrobial prophylaxis for orthopedic operations. Cefuroxime-impregnated cement lowered the risk of deep infection after primary total knee arthoplasty.20 Other studies have been inconclusive regarding superiority of antimicrobial-impregnated bone cement versus conventional therapies.21 Confounding this issue is the lack of standards regarding antimicrobial-impregnated cements. An array of drugs, from aminoglycosides to macrolides, is used in these preparations. Some cements are produced commercially whereas others are made in the operating room. The long-term durability of impregnated cements is also unknown, as the addition of antimicrobials may reduce the tensile strength of bone cement. 
Further study is needed before antimicrobial-impregnated bone cements can be recommended as an alternative to preoperative prophylaxis with traditional antimicrobials.
Antimicrobial irrigation may also be encountered in the surgical arena as an adjunct or alternative to traditional parenteral antimicrobial prophylaxis. Irrigation of wounds allows debris removal as well as an additional way to lessen bacterial contamination. However, as with the antimicrobial bone cement, evidence is mixed on the advantages of using this approach. Irrigation with detergent solutions, rather than antimicrobials, appears to provide the same results but with less wound-healing problems encountered with antimicrobial irrigation.22 Additionally, because antimicrobial irrigation solutions are not commercially available, irrigants are often made in the operation rooms, allowing for the possibility of higher than or lower than desired concentrations. If concentrations are higher than desired, local chemical irritation may occur as well as systemic absorption and toxicity. If concentrations fall below desired targets, development of resistant organisms may occur. Further study is required before antimicrobial irrigation is recommended for use in surgical prophylaxis.
With the increase of CA-MRSA, increased importance has been placed on screening for S. aureus, especially MRSA and decolonization. Surgical patients with nasal colonization of S. aureus have a higher risk of an SSI due to S. aureus, and decolonization leads to a lower incidence of SSIs.23-25 However, while this evidence may imply the opportunity for some real benefits in the surgical population, a clear consensus on how the nasal colonization should be approached has not been reached. British guidelines recommend an attempt at decolonization for patients undergoing planned surgical procedures to minimize the risk of infection.26 Harbarth and colleagues suggest MRSA screening be targeted to patients undergoing elective surgical procedures that have a high risk of MRSA infection. In addition, each hospital’s infection control team, along with the surgical team, should analyze their patient population and MRSA epidemiology to appropriately select screening guidelines,27 keeping in mind state and federal statutes regarding the use of active surveillance cultures. Screening methods that utilize rapid, PCR-based testing may provide an advantage in quickly identifying colonized patients and allowing decolonization to occur prior to surgery.
The most studied approach to eradication of methicillin-sensitive S. aureus (MSSA) and/or MRSA has been mupirocin applied to the anterior nares for 5 days prior to surgery.28 Additionally, skin decolonization with 4% chlorhexidine for 5 days prior to surgery has also been recommended. While decolonization of the anterior nares is the most common and most studied, some controversy exists because patients may be colonized elsewhere (rectum, throat, vagina, etc.) and often do not receive complete decolonization.28 Furthermore, decolonization usually does not lead to life-long eradication. Other drugs, both topical and systemic, have been studied for decolonization/eradication of MRSA, but a review of randomized controlled trials for the eradication of MRSA found insufficient evidence for the use of any agent for eradication of MRSA.29 Further studies are needed to elucidate this area of surgical prophylaxis.
Principles of Antimicrobial Prophylaxis
Route of Administration
IV antimicrobial administration is the most common delivery method for su rgical prophylaxis. IV administration ensures complete bioavailability while minimizing the impact of patient-specific variables. Oral administration is also used in some bowel operations. Nonabsorbable compounds like erythromycin base and neomycin are given up to 24 hours prior to surgery to cleanse the bowel. Note that oral agents are used adjunctively and do not replace IV agents.
Timing of First Dose
For prevention of SSIs, correct timing of antimicrobial administration is imperative so as to allow the persistence of therapeutic concentrations in the blood and wound tissues during the entire course of the operation. The National Surgical Infection Prevention Project recommends infusing antimicrobials for surgical prophylaxis within 60 minutes of the first incision. Exceptions to this rule are fluoroquinolones and vancomycin, which can be infused 120 minutes prior to avoid infusion-related reactions.1 No consensus has been reached on whether the infusion should be complete prior to the first incision. However, if a proximal tourniquet is used, antimicrobial administration should be complete prior to inflation.
Administration of the antimicrobial should begin as close to the first incision as possible. This is important for antimicrobials with short half-lives so that therapeutic concentrations are maintained during the operation and reduce the need for redosing. Beginning the antimicrobial infusion after the first incision is of little value in preventing SSI. Administration of the antimicrobial after the first incision had SSI rates similar to patients who did not receive prophylaxis.30
Dosing and Redosing
The goal of antimicrobial dosing for surgical prophylaxis is to optimize the pharmacodynamic parameter of the selected agent against the suspected organism for the duration of the operation. Dosing recommendations can vary between institutions and guidelines. Clinical judgment should be exercised regarding dose modifications for renal function, age, and especially weight. Obese patients often require higher doses than do nonobese patients.1 Morbidly obese patients (body mass index greater than 40) who received 2 g of cefazolin had a lower incidence of SSI compared to patients receiving 1 g.31 An advisory statement from the National Surgical Infection Prevention Project suggested that for patients less than 80 kg, cefazolin should be dosed at 1 g; patients that are 80 kg or greater should receive 2 g of cefazolin for adequate prophylaxis.1
If an operation exceeds two half-lives of the selected antimicrobial, then another dose should be administered.1 Repeat dosing reduces rates of SSI. For example, cefazolin has a half-life of about 2 hours, thus another dose should be given if the operation exceeds 4 hours. The clinician should have extra doses of antimicrobial ready in case an operation lasts longer than planned.
Duration
The National Surgical Infection Prevention Project and published evidence suggest that the continuation of antimicrobial prophylaxis beyond wound closure is unnecessary.1 The duration of antimicrobial prophylaxis should not exceed 24 hours (48 hours for cardiac surgery); additional doses of antimicrobial past this time point do not demonstrate added benefits. Longer durations of antimicrobial prophylaxis are advocated by some guidelines and will be discussed later.
TREATMENT
Antimicrobial Prophylaxis in Specific Surgical Procedures
Gynecologic and Obstetric
Enteric gram-negative bacilli, anaerobes, group B streptococci, and enterococci are all possible pathogens that may be encountered in gynecologic or obstetric surgeries. For patients undergoing hysterectomy, cefoxitin or cefotetan are appropriate therapies (Table 85–3). Cefazolin or ampicillin/sulbactam may be used. In the case of β-lactam allergy, the following regimens are appropriate: clindamycin combined with gentamicin, aztreonam, or ciprofloxacin; metronidazole combined with gentamicin or ciprofloxacin, or clindamycin monotherapy. Metronidazole monotherapy is also indicated but is less effective than other regimens.1
Table 85–3 Recommended Regimens for Antimicrobial Prophylaxis of Specific Surgical Proceduresa
Cesarean sections are stratified into low- and high-risk groups. Patients who undergo emergency operations or have cesarean sections after the rupture of membranes and/or onset of labor are considered high risk. Prophylactic antimicrobials are most beneficial for high-risk patients but are used in both groups. Antimicrobial regimens similar to those for hysterectomy are appropriate. Antimicrobials should not be administered until after the first incision and the umbilical cord has been clamped. This practice prevents potentially harmful antimicrobial concentrations from reaching the newborn.
Orthopedic Surgery
Orthopedic operations are generally clean and are done under controlled conditions. Likely pathogens include grampositive cocci, mostly staphylococci. In the case of total joint (knee and hip) arthroplasty, cefazolin is the antimicrobial of choice. Patients with a β-lactam allergy should receive either clindamycin or vancomycin. Antimicrobial prophylaxis should not exceed 24 hours and does not need to be continued until all drains and catheters have been removed. Antimicrobial-impregnated bone cement can be useful in lowering infection rates in orthopedic surgery but has not been approved for prophylaxis.
Cardiothoracic and Vascular Surgery
Cefazolin or cefuroxime are appropriate for prophylaxis in cardiothoracic and vascular surgeries. In the case of β-lactam allergy, vancomycin or clindamycin are advised. Debate exists on the duration of antimicrobial prophylaxis. SSIs are rare after cardiothoracic operations, but the potentially devastating consequences lead some clinicians to support longer periods of prophylaxis. The National Surgical Infection Prevention Project cites data that extending prophylaxis beyond 24 hours does not decrease SSI rates and may increase bacterial resistance.1 However, the Society of Thoracic Surgeons issued practice guidelines in 2006 to extend the duration of antibiotics to 48 hours following cardiac surgeries.32 Duration of therapy should be based on patient factors and risk of development of an SSI.
Patient Encounter 1, Part 1
AD is a 60-year-old woman with a history of poorly controlled diabetes mellitus and MSSA nasal colonization. She weighs 54 kg (119 lb) and is 5’ 1” (155 cm) tall. She presents today for a hysterectomy. She has no allergies to any medications. The surgeon approaches you for recommendations on prophylactic antibiotic use.
PE:
VS: BP 128/76 mm Hg, P 76 bpm, RR 15 per minute, T 36.4°C (97.5°F)
Labs: WBC 5 × 103/mm3 (5 × 109/L), serum creatinine 80 μmol/L (0.9 mg/dL), glucose 5.3 mmol/L (95 mg/dL)
What drug would you choose for this operation and why?
What organisms are likely to be encountered in this operation?
The surgeon asks about using metronidazole as a solo agent; what is your opinion on this?
The surgeon agrees with your decision and wants to begin infusing the antibiotic 1 hour after the first incision. Comment on this.
What other interventions besides antibiotic use could prove useful in lowering AD’s risk of SSI?
Patient Encounter 1, Part 2
AD has been admitted to the ward after completion of her hysterectomy. A physical examination is performed and laboratory data are collected in the immediate postoperative period. AD complains of tenderness around the incision site but no erythema is noted.
PE:
VS: BP 132/80 mm Hg, P 82 bpm, RR 20 per minute, T 37.8°C (100°F)
Labs: WBC 11 × 103/mm3 (11 × 109/L), serum creatinine 88 μmol/L (1 mg/dL), glucose 5.55 mmol/L (100 mg/dL)
Based on the available data, does AD have an SSI?
What interventions may increase AD’s comfort?
How should AD be screened for SSI?
How long should AD be followed in order to identify a possible SSI?
Patient Encounter 2
GL is a 56-year-old male who presents to the emergency department with crushing chest pain described as a “10/10” and shortness of breath. He weighs 82 kg (180 lb) and is 5’ 9” (175 cm) tall. An ECG reveals an elevated ST segment and lab data are significant for elevated troponins. GL is diagnosed with acute myocardial infarction. After GL is stabilized, the decision is made to place multiple stents. The surgeon consults with you on recommendations for antibiotic prophylaxis. Significant history for GL: allergy to amoxicillin (anaphylaxis), smokes two packs of cigarettes per day, and lives with his wife and two children.
PE:
VS: BP 162/95 mm Hg, P 120 bpm, RR 28 per minute, T 35.8°C (96.4°F)
Labs: Serum creati nine 0.9 mg/dL (80 μmol/L), troponins 0.8 ng/mL (0.8 mcg/L)
The surgeon wants to use vancomycin for this case; what is your opinion on this?
The surgeon decides to use vancomycin at a dose of 1 g over 30 minutes. During the infusion, GL experiences a rash and a call is made for an epinephrine pen. What is happening to GL and how would you alter the therapy?
What is the risk of overuse of vancomycin in hospitals and what pathogens are becoming problematic?
Colorectal Surgery
Antimicrobial prophylaxis for colorectal operations must cover a broad range of gram-positive, gram-negative, and anaerobic organisms. Strategies include oral antimicrobial bowel preparations, parenteral antimicrobials, or both. Oral prophylaxis combinations of neomycin and erythromycin or neomycin and metronidazole are common. Oral antimicrobials should be administered at 19, 18, and 9 hours prior to surgery. A delay in surgery may require a redose, depending on the length of postponement. For parenteral prophylaxis, cefoxitin or cefotetan is appropriate. Cefazolin combined with metronidazole or ampicillin/sulbactam is an effective alternative if antianaerobic cephalosporins are not available. For patients with β-lactam allergies, use clindamycin combined with gentamicin, aztreonam, or ciprofloxacin; metronidazole combined with gentamicin or ciprofloxacin is also appropriate.
Appendectomy is one of the most common intra-abdominal operations. Antimicrobial prophylaxis used for appendectomy is similar to that used for colorectal regimens. In the case of ruptured appendix, antimicrobials are used for treatment, not prophylaxis.
OUTCOME EVALUATION
The clinician should consistently follow-up postoperative patients and screen for any sign of SSI. According to CDC criteria, SSI may appear up to 30 days after an operation and up to 1 year if a prosthesis is implanted.5 This period often extends beyond hospitalization so patients should be educated on warning signs of SSI and be encouraged to contact a clinician immediately if necessary. The presence of fever or leukocytosis in the immediate postoperative period does not constitute SSI and should resolve with proper patient care. Distal infections, such as pneumonia, are not considered SSIs even if these infections occur in the 30-day period. The appearance of the surgical site should be checked regularly and changes should be documented (e.g., erythema, drainage, or pus). The presence of pus or other signs suggestive of SSI must be treated accordingly. Any wound requiring incision and drainage is considered an SSI regardless of appearance. Prompt cultures should be collected and appropriate antimicrobial therapy initiated to reduce any chance of morbidity and mortality.
Patient Care and Monitoring
• Conduct a thorough medication history including prescription and nonprescription medications, as well as herbals and vitamins.
• Verify the patient’s allergy history and the type of reaction experienced. Attempt to discern between true allergy and adverse event. β-Lactam-allergic patients may receive clindamycin, vancomycin, or other antimicrobials. Cross-reactivity between penicillin allergy and cephalosporins is low but cephalosporins should be avoided in patients with a history of anaphylaxis to penicillins.
• Document the type of operation the patient is undergoing. Verify the surgical procedure with the patient.
• Prophylactic antimicrobials should be started within an hour of the first incision to optimize patient outcomes. Exceptions to this include vancomycin and fluoroquinolones.
• The patient should be monitored for signs of an allergic reaction during the operation. These include rash, hives, difficulty breathing, or substantial drops in blood pressure.
• Major breaks in surgical technique may cause the classification of the operation to change and require adjustments in antimicrobial prophylaxis.
• The patient should be monitored for signs and symptoms of infection postoperatively. These could include pus, erythema, and fever. If signs consistent with SSI appear, cultures should be taken and additional antimicrobial therapy should be considered.
• Patients being discharged should be counseled on recognizing signs and symptoms of SSI. An SSI can appear up to 30 days after an operation is completed.
Abbreviations Introduced in This Chapter
Self-assessment questions and answers are available at http://www.mhpharmacotherapy.com/pp.html.
REFERENCES
1. Bratzler DW, Houck PM, for the Surgical Infection Prevention Guideline Writers Workgroup. Antimicrobial prophylaxis for surgery: An advisory statement from the National Surgical Infection Prevention Project. Am J Surg 2005;189:395–404.
2. Barie PS, Eachempati SR. Surgical site infections. Surg Clin North Am 2005;85:1115–1135.
3. Kirkland KB, Briggs JP, Trivette SL, et al. The impact of surgical site infections in the 1990s: Attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol 1999;20:725–730.
4. Hollenbeak CS, Murphy D, Dunagan WC, et al. Nonrandom selection and the attributable cost of surgical-site infections. Infect Control Hosp Epidemiol 2002;23:174 –176.
5. Mangram AJ, Horan TC, Pearson ML, et al. Guideline for prevention of surgical site infection, 1999. Infect Control Hosp Epidemiol 1999;20:247–266.
6. Department of Health and Human Services: Centers for Medicare & Medicaid Services. Medicare Program; Changes to the Hospital Inpatient Prospective Payment Systems and Fiscal Year 2008; Final Rule. Federal Register 2007;72:47200–47206.
7. Dionigi R, Rovera F, Dionigi G, et al. Risk factors in surgery. J Chemother 2001;13:6–11.
8. Pessaux P, Atallah D, Lermite E, et al. Risk factors for prediction of surgical site infections in “clean surgery.” Am J Infect Control 2005;33:292–298.
9. Devlin JW, Kanji S, Janning SW, et al. Antimicrobial prophylaxis in surgery. In: Dipiro JT, Talbert RL, Yee GC, et al. Pharmacotherapy: A Pathophysiologic Approach, 5th ed. New York: McGraw-Hill, 2002:2111–2122.
10. Finkelstein R, Rabino G, Mashiah T, et al. Vancomycin versus cefazolin prophylaxis for cardiac surgery in the setting of a high prevalence of methicillin-resistant staphylococcal infections. J Thorac Cardiovasc Surg 2002;123:326–332.
11. Itanu KMF, Wilson SE, Awad SS, et al. Ertapenem versus cefotetan prophylaxis in elective colorectal surgery. N Engl J Med 2006;355:2640–2651.
12. Centers for Medicare & Medicaid Services and The Joint Commission. The Specifications Manual for National Hospital Inpatient Quality Measures (Specifications Manual) Version 3.0b. Available at http://www.qualitynet.org/dcs/contentserver?cid=1141662756099&pagename=Qnetpublic%2Fpage%2FQnetTier2&c=page. Last accessed 29 September 2009.
13. Schafer JA, Mateo N, Parlier GL, Rotschater JC. Penicillin allergy skin testing: What do we do know? Pharmacotherapy 2007;27:542–545.
14. Pichichero ME. A review of evidence supporting the American Academy of Pediatrics recommendation for prescribing cephalosporin antibiotics for penicillin-allergic patients. Pediatrics 2005;115:1048–1057.
15. Apter AJ, Kinman JL, Bilker WB, et al. Is there cross-reactivity between penicillins and cephalosporins? Am J Med 2006;119:354.e11–e20.
16. Weed HG. Antimicrobial prophylaxis in the surgical patient. Med Clin North Am 2003;87:59–75.
17. Kurz A, Sessler D, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. N Engl J Med 1996;334:1209–1215.
18. Ingels C, Debaveye Y, Milants I, Buelens E, et al. Strict blood glucose control with insulin during intensive care after cardiac surgery: Impact on 4-years survival, dependency on medical care, and quality of life. Eur Heart J 2006;27(22):2716–2724.
19. Greif R, Akca O, Horn E, et al., for the Outcomes Research Group. Supplemental perioperative oxygen to reduce the incidence of surgical-wound infection. N Engl J Med 2000;342:161–167.
20. Chiu FY, Chen CM, Lin CF, et al. Cefuroxime-impregnated cement in primary total knee arthroplasty. J Bone Joint Surg 2002; 84:759–762.
21. Joseph TN, Chen AL, Di Cesare PE. Use of antibiotic-impregnated cement in total joint arthroplasty. J Am Acad Orthop Surg 2003;11: 38–47.
22. Fletcher N, Sofianos D, Berkes MB, Obremskey WT. Prevention of perioperative infection. J Bone Joint Surg Am 2007;89:1605–1618.
23. Wilcox MH, Hall J, Pike H, et al. Use of perioperative mupirocin to prevent methicillin-resistant staphylococcus aureus (MRSA) orthopaedic surgical site infections. J Hosp Infect 2003;54:196–201.
24. Perl TM, Cullen JJ, Wenzel RP, et al. Intranasal mupirocin to prevent postoperative Staphylococcus aureus infections. N Engl J Med 2002;346:1871–1877.
25. Munoz P, Hortal J, Giannella M, et al. Nasal carriage of S. aureus increases the risk of surgical site infection after major heart surgery. J Hosp Infect 2008;68:25–31.
26. Coia JE, Duckworth GJ, Edwards DI, et al. Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities. J Hosp Infect 2006;63:S1–S44
27. Harbath S, Fankhauser C, Schrenzel J, et al. Universal screening for methicillin-resistant Staphylococcus aureus at hospital admission and noscomial infection in surgical patients. JAMA 2008;299:1149–1157.
28. Loveday HP, Pellowe CM, Jones SRLJ, Pratt RJ. A systematic review of the evidence for interventions for the prevention and control of meticillin-resistant Staphylococcus aureus (1996–2004): Report to the Joint MRSA Working Party (Subgroup A). J Hosp Infect. 2006;63:S45–S70.
29. Loeb M, Main C, Walker-Dilks C, Eady A. Antimicrobial drugs for treating methicillin-resistant Staphylococcus aureus colonization. Cochrane Database of Systemic Reviews 2003, Issue 4.
30. Stone HH, Hooper CA, Kolb LD, et al. Antibiotic prophylaxis in gastric, biliary and colonic surgery. Ann Surg 1976;184:443–452.
31. Forse RA, Karam B, MacLean LD, et al. Antibiotic prophylaxis for surgery in morbidly obese patients. Surgery 1989;106:750–756.
32. Edwards FH, Engelman RM, Houck P, et al. The Soceity of Thoracic Surgeons Practice Guideline Series: Antibiotic Prophylaxis in Cardiac Surgery, Part I: Duration. Ann Thorac Surg 2006;81:397–404.