Wise use of perioperative antibiotics

Wise use of perioperative antibiotics

Home Study Program JUNE 2005, VOL 81, NO 6 Home Study Program Wise use of penoperative antibiotics T he article "Wise use of perioperative antibio...

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Home Study Program

JUNE 2005, VOL 81, NO 6

Home Study Program Wise use of penoperative antibiotics


he article "Wise use of perioperative antibiotics" is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Rebecca Holm, RN, MSN, CNOR, clinical editor, with consultation from Susan Bakewell, RN, MS, BC, education program professional, Center for Perioperative Education. Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is June 30,2008. Complete the examination answer sheet and learner evaluation found on pages 1277-1278 and mail with appropriate fee to

AORN Customer Service c/o Home Study Program 2170 S Parker Rd, Suite 300 Denver, CO 80231-5711

or fax the information with a credit card number to (303) 750-3212. You also may access this Home Study via AORN Online at

http://wWw.aorn.org/journal/homes tudy/default. htm.

BEHAVIORAL OECJECTIVES After reading and studying the article on perioperative use of antibiotics, nurses will be able to

1. describe patients' physiological responses to the presence of bacteria,

2. explain antibiotic effectivenessrelated to the pharmacotherapeutic property of mutation prevention,

3. discuss current theories of how long antibiotics should be administered after surgery,


This program meets criterio for CNOR and CRNFA recertificotion, os well as other continuing educotion requirements. A minimum score of 70% on the multiplechoice examination is necessary to earn 1.8 contact hours for this independent study. Purpose/Goal: To educote perioperative nurses about perioperative use of ontibiotics.

describe the new guidelines published in the Medical Letter for surgical infection prophylaxis, and

5. identdy how perioperative nurses help reduce surgical site infections through wise use of antibiotics.




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Home Study Program Wise use of perioperative antibiotics Donna J. Plonczynski, RN ospital-acquired infections are a major concern for perioperative urses. Nearly 27 million people have surgery every year, and approximately 500,000 will acquire nosocomial surgical site infections (SSIs) of varying severity.’Patients who acquire infections experience longer hospital stays and hgher morbidity and mortality rates. In addition, their care is more costly2 Although infection rates are affected by patient factors and the type and length of surgery performed? patients undergoing high-risk procedures who receive inadequate antibiotic prophylaxis before surgery have 2.32 times greater risk of acquiring an SSI compared to those who receive adequate antibiotic prophylaxis.’ Correct antibiotic prophylaxis has been shown to reduce SSIs and


ABSTRACT NOSOCOMIAL SURGICAL SITE INFECTIONS (SSIs), especially those caused by antibiotic-resistant organisms, are a major concern for perioperative nurses. Administeringthe correct antibiotic at its effective dose within the optimal time frame can help prevent SSIs. THE SIGNIFICANT RELATIONSHIP between microbial resistance and overuse of antibioticsjustifies an examination of practices and a move away from widespread antibiotic administration. NEW ANTIBIOTIC GUIDELINES and research support recommendationsfor antibiotic administration for specific cardiac, colorectal, gynecologic, ophthalmologic, orthopedic, and urinary swgical pmedures. Perioperativenurses can help protect their patients from nosocomial SSIs by using this clinical evidence. AORNJ 81 (June2005) 1260-1272.



hospital costs.5The purposes of this article are to discuss antibiotic effectiveness and resistance and present the latest research and guidelines regarding antibiotic prophylaxis to prevent SSIs in surgical patients.

INNATE AND ACQUIRED RESPONSES Any surgical break in the skin barrier allows bacteria from the skin, air, and environment to enter a surgical site even if colonization does not progress to a clinical infection.6 A patient’s response to the presence of bacteria is classified as either innate or acquired. Innate factors, such as how well a patient’s neutrophils and macrophages function, are responsible for eradicating foreign substances in the body. Innate immunological factors differ between individuals and within each individual and are affected by the aging proce~s.~ Acquired factors that can impair a patient’s immune response include chronic diseases (eg, diabetes, Cushing’s disease), medications (eg, corticosteroids, blood transfusions), and certain conditions (eg, malnutrition, hypothermia). In addition to the normal aging of the population, longevity of adults with multiple chronic illnesses is resulting in an increased risk of SSIs. ULTIMATE WEAPON OR SURGICAL


Less than 80 years after their introduction in 1935, antibiotics evolved from the ultimate weapon against the primary causes of morbidity and mortality to a significant surgical risk factor. Antibiotic overuse has been responsible for the development of bacteria that resist eradication.HUndergoing surgery has been shown to increase a hospitalized patient’s risk of acquiring an antibiotic-resistant infection by 62Y0.~


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Figure 1 Antibiotic serum concentration over time compared to an antibiotic's minimum inhibitory concenttation for preventing bacterial growth i s a major determinant of an antibiotic's effectiveness.


These worrisome bacteria include amikacin-resistant Pseudomonas aerugifiosu, methicillin-resistant Staphylococcus uureus (MRSA), and vancomycinresistant enterococci.Judiciousantibiotic use in the OR is warranted, however, because of the increase in higher-risk surgical patients and the rising rate of microbial resistance to antibiotics. To address the significance of infection and microbial resistance, the Centers for Disease Control and Prevention has developed an education program for health care facilities. The program's four tenets are to 0 prevent infection, 0 use antibiotics wisely, 0 diagnose and treat infections accurately, and 0 prevent further transmission of the infection.'O An SSl may occur because a patient's defense mechanisms are weakened or as a result of the amount and virulence of the bacteria and the patient's wound characteristics." As a result of differing infection control procedures in health care facilities (eg, most notably antibiotic administration practices), rates of infection" and antibiotic resistance differ by hospital'*and by ~0untry.l~ Wise use of antibiotics is one of the methods by which perioperative nurses affect the rate of SSIs for their patients," particularly because many patient risk factors for infection are nonmalleable.'5 Un-



derstanding appropriate antibiotic choice, dose, and timing is indispensable knowledge to protect surgical patients. In addition to administering antibiotics, perioperative team members help control the rate of SSIs by 0 facilitating an optima1 wound microenviroment, 0 reducing or eliminating contact with bacteria, and promoting the patient's defenses.

ANTXBXOTIC E F F E ~ E N E AND S S RESISTANCE Antibiotic effectiveness is partly related to its pharmacotherapeutic property of mutation prevention.16 Mutation prevention is essential to prohibit a bacterium from developing resistance to antibiotics to which it is exposed. The calculations for antibiotic effectiveness are based on pharmacokinetic and pharmacodynamic principles.I6A mutation prevention concentration predicts bacterial suppression or obliteration by 0 antibiotic serum concentrations, 0 area under the concentration-time curve (AUC), and 0 minimum inhibitory concentration (MIC) values (Figure 1). Antibiotic serum concentration is the level of medicine in the patient's blood at one point in time. An example of the concentration measure is a trough level of an aminoglycosideantibiotic taken 30 minutes before the next infusion. To understand the AUC, two concentration terms are useful. The CmXis the highest concentration level that a medication reaches in the serum after administration. When half of that highest concentration is eliminated (ie, its half-life) the concentration is referred to as C W ~ . The AUC is the amount of medication concentration over time, in contrast

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to two snapshots of concentration. The AUC includes the medication's concentration from administration until it is no longer measurable in the patient's serum. The MIC measures the least amount of antibiotic that causes inhibition of the bacteria in the laboratory. This measure is specific to each antibiotic and bacteria and varies even within species, such as when an individual bacterium becomes resistant to an antibiotic. The AUC/MIC value is ideal for determining effectiveness of an antibiotic because it incorporates the myriad elements that influence eradication of the bacteria (eg, antibiotic concentration over time, bacterial sensitivity.)"


The relationship between antibiotic resistance and the high use of antibiotics in hospitals has been suspect for more than 20 years." Researchers now have demonstrated this relationship. One study looked at antibiotic use and MRSA rates during a four-year period. It found that increased use of nearly all antibiotics corresponded to increased rates of the resistant bacteria." The resistance relationship included penicillins with beta-lactamase inhibitors, macrolides, third-generation cephalosporins, fluoroquinolones, and aminoglycosides. Tetracycline was the only antibiotic studied that did not correspond with an alarming increase in MRSA rates.20 The relationship between excess antibiotic use and resistant bacteria is international; many other countries have identified SURGICAL SITE this same link.I3 INFEPC ROPHYLAT X SI ION In contrast to these grim findings, a The rate of SSIs can be study that examined a change in antibitibiotic reduced with the correct otic use in several large hospitals found choice of antibiotic, prop- that decreasing the overuse of antibier timing of administra- otics over time led to improved patient tion to in&sion, and limit- outcomes.'* Departments that reduced ing prolonged antibiotic antibiotic use to approved standards use after surgery. Al- developed less antibiotic resistance durof though the first two ing the four-year study period. measures are mainstays of pharmacological adPERIOPERATIVE ANB TO IC TI PROPHYLAXIS ministration by perioperAlthough antibiotic administration ative nurses, the length of standards have been in place for years, administration after" sur- some health care practitioners have gery has become a topic been unsure of the best antibiotic protoof increasing interest. col for surgical prophylaxis.2' In 2004, Researchers have evaluated the ideal new guidelines were published in the length of time to continue antibiotic ad- Medical Letter that address these issues.22 ministration after surgery. One study These guidelines are the result of extenfound that patients who underwent pro- sive literature reviews and are an examlonged antibiotic administration did not ple of evidence-based practice. The have a decrease in SSIS, but they did guidelines are not intended to superhave higher rates of antibiotic resist- sede sound clinical judgment, including ance.'* This finding suggests that pro- consideration of the patient's allergies longing antibiotic administration actual- and medical history. Alternate regimens ly may be deleteriousto the patient while are offered within the guidelines to not improving overall infection rates. address specific situations.

One st&"found that patients who underwent prolonged an administration @p~enced higher rates antibiotic resistance.




Although, prophylaxis for many surgical procedures is discussed, readers should refer to the guidelines in the Medical Letter to obtain complete information.z2 0 In general, the new guidelines support administration of parenteral prophylactic antimicrobialsin a single nT dose begun within 60 minutes before the incision is made." If vancomycin or a fluoroquinolone is used, the infusion should be started 60 minutes to 120 minutes before the incision is made to minimize the possibility of an infusion reaction near the time of anesthesia induction and to allow adequate tissue levels by the time of incision. For prolonged procedures, additional intraoperative doses should be administered at intervals one to two times the half-life of the medication for the duration of the procedure. Prophylactic continuation of antibiotics after most surgical procedures is not recommended; however, continuation of antibiotic treatment is recommended for five days postoperatively if patients have bacterial contamination in the wound (eg, ruptured viscus, compound fracture). This action is taken because the patient needs actual treatment, rather than prophylaxis, for tlus infection. CARDIAC SURGERY. More than 500,000 coronary artery bypass graft surgeriesare performed in the United States annuallyz3 The usual infectious organisms of concern are Staphylococcus aureus and Staphylococcus epidermidis; therefore, the new guidelines recommend antibiotic prophylaxis with cefazolin 1g to 2 g IV or cefuroxime 1.5 g IV? Alternatively, vancomycin 1 g IV is recommended for patients in hospitals with hgh rates of MRSA or methicillin-resistant Staphylococcus epidermidis (MRSE), and for patients with either a history of previous MRSA or an allergy to penicillins or cephalosporins."

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The guidelines advise against routine use of antibiotic prophylaxis with cardiac catheterization. A study that determined there was no indication for the use of prophylactic vancomycin in pacemaker implantationsor cardiac catheterization unless the hospital has a high rate of MRSA or MI&E supports this guideline.6 COLORECTAL SURGERY. The optimal choice of antibiprolonged otics for SSI prophylaxis in colorectal surgery has procedures, been studied extensively. additional Research on patients undergoing colorectal surintraoperative gery compared groups that were given oral doses of antibiotics before the proc e d ~ r e . ~ Both * groups antibiotics received equal mechanical bowel preparation and a should be cephalosporin before surgery. One group received additional oral prophylax- administered is and had a significantly the duration of decreased rate of SSIs. An oral antibiotic regimen is the procedure. one evidence-based practice recommendation of the new guidelines. The guidelines for nonemergent colorectal surgery recommend treatment against the common pathogens of enteric gram-negativebacilli, anaerobes, and enterococci with oral and parenteral For nonemergent procedures, appropriate diet restrictions and bowel preparation are needed. One oral regimen is neomycin 1 g plus erythromycin 1 g at 1 I'M, 2 PM, and 11PM the day before a surgery scheduled for 8 AM. An alternate oral regimen is neomycin 2 g plus metronidazole 2 g at 7 I'M and 11 I'M the day before a surgery scheduled for 8 AM. The parentera1 antibiotic choices include either cefotetan 1g to 2 g N or cefoxitin 1g to 2 g nT. An alternate parenteral choice is





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cefazolin 1 g to 2 g IV plus metronidazole 0.5 g to 1 g IV. GYNECOLOGIC SURGERY. Approximately 600,000 hysterectomies are performed annually in the United States.” One group of researchers found that higher posthysterectomy infection rates were more common with abdominal incisions when compared to either laparoscopic or vaginal approaches.” The new guidelines cautiously recommend antibiotic prophylaxis for all approaches to guard against enteric gram-negative bacilli, anaerobes, group B Streptococcus, and One study enterococci.” Either cefotetan 1 g to 2 g IV,cefoxitin suggests that 1g to 2 g IV,or cefazolin 1 g to 2 g N may be adminmatching the istered before the start of a risk for infection procedure. OPHTHALMIC SURGERY. Patients undergoing surgerwith antibiotic ies that invade the ophglobe are suscepadministration thalmic tible to infections from a variety of organisms, inresults in cluding Staphylococcus epidermidis, Sfaphylococciis optimal mireus, streptococci, enoutcomes with teric gram-negative bacilli, and pseudomonas.” These infections are best lower risk prevented by treatment for two to 24 hours with a antibiotic variety of ophthalmic drops, including gentamresistance. icin, tobramycin, and ciprofloxacin, among others. Another treatment choice is the use of cefazolin 100 mg by subconjunctival injection during surgery. As a result of rising antibiotic resistance and the poor outcome of patients with endophthalmitis, there is evolving evidence to support beginning prophylaxis three days before cataract procedures in contrast to hours before the incision is made,” but this is not yet





included in the recommendation. ORTHOPEDIC SURGERY. Orthopedic procedures present risk for infections by Staphylococcus aureus and Staphylococcus epiderrnidis.22Cefazolin 1 g to 2 g IV is the treatment of choice in hospitals with a low rate of SSIs caused by MRSA or MRSE. Vancomycin 1 g should be given in hospitals with high rates of SSIs caused by MRSA or MRSE to reduce the risk for osteomyelitis. In addition, vancomycin is used in patients who were colonized previously with MRSA or who are allergic to penicillins or cephalosporins.In procedures requiring a tourniquet, the guidelines remind health care practitioners to infuse the entire dose before inflation to ensure adequate tissue concentration. Researchers found that arthroscopy generally is not a high-risk surgery for SSIs.” Researchers further note that routine use of antibiotics is not indicated because of medication costs and patients’ risks for an allergic reaction.*’ The guidelines published in the Medical Letter support this study‘s findings.’z UROLOGICSURGERY. Some patients who undergo urologic surgery experience improved postoperative outcomes with antibiotic prophylaxis. Researchers stratified patients undergoing urologic surgery by invasiveness of the procedure and degree of contamination.28 The SSI risk stratifications were matched with appropriate antibiotic regimens. These regimens resulted in lower costs and less antibiotic use without a change in the SSI rate compared to results from a similar group of surgical patients from the previous year. This study suggests that matching the risk for infection with antibiotic administration results in optimal outcomes with lower risk for antibiotic resistance, while also lowering costs. Most urologic procedures do not require preoperative antibiotic prophylaxis.2’ It is recommended, however,


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Perioperative quality care initiatives include recording infection rates &y type of surgery, surgical personnel, suite, and patient data to identi& variables that might increase risk for surgical site infections. that patients without demonstrated sterile urine, who have preoperative catheters in place, who are undergoing transrectal prostatic biopsy, or who are undergoing surgeries involving prosthetic material receive antibiotics to prevent contamination with enteric gram-negative bacilli and enterococci. The choice of prophylaxis is ciprofloxacin 500 mg orally or 400 mg IV. The guidelines in the Medical Letter also indicate that there is some evidence of reduced postoperative infection rates in patients treated before transurethral prostatectomy, although the guidelines do not yet recommend this treatment.”

DISCUSSION Antibiotic-resistant organisms are an increasing concern in perioperative settings. The significant relationship between resistance and overuse of antibiotics is well established and justifies a change in perspective that previously supported widespread antibiotic use. Fortunately, it has been shown that a change in overuse patterns can decrease microbial resistance to antibiotics. To administer perioperative antibiotics wisely, health care practitioners need increased knowledge of medicationpharmacodynamics, the relationship between overuse and microbial resistance, and research-based treatment guidelines. Although new antibiotics are being developed, the potential misuse of them would only perpetuate existing problems with microbial resistance. A multidisciplinary approach involving pharmacists, physicians, perioperative nurses, infection control experts, and other health care practitioners is needed to adequately address this issue. Interestingly, surveillance itself also is effective. Observing and reporting data on infections and antibiotic resistance leads to decreases in both rates. Effective surveillance systems can be developed on both the nationaP9and levels.

IMPLICATIONS FOR PERIOPERATIVE NURSES The influence of national standards on individual practice and the outcome in patient safety measures can be evaluated for effectiveness. Surveillance improves patient outcomes, so asking questions and having a system to track the answers could help reduce SSIs and microbial resistance in individual perioperative departments. The perioperative setting is conducive to quality care initiatives that include recording infection rates by type of surgery; surgical personnel; suite; and patient data, such as age and medical conditions, to address any variables that might increase a patient’s risk for SSIs. In addition, variables that decrease SSIs also can be recognized by the health care facility. Nurses are in an ideal role to evaluate antibiotic use in the perioperative setting. An example of an issue that may be of interest to perioperative nurses is whether there is a significantrelationship between antibiotic use and resistance in their department. This rate can be compared to national and international averages for evaluation of current and future patterns. Wise antibiotic administration results from multifaceted knowledge about available medications. Continued research on safe and effective antibiotic administration in the perioperative setting necessitates that perioperative nurses continue to educate themselves as scientific knowledge emerges.*:*

Donna J. Plonczynski,RN, PhD, is an advanced practice nurse and assistant professor at the School of Nursing, Northern Illinois University, DeKalb, 111.


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