SPA Meeting Reviews

Saturday Session VI: Drugs and Dresses: Anesthesiologists Preventing Surgical Site Infections

Antibiotics Now: New Paradigms for Cefazolin, Vancomycin, and the Penicillin(PCN)-Allergic Patient

Reviewed by: Erin S. Williams, MD, FAAP
Texas Children’s Hospital
Baylor College of Medicine

Dr. Williams

Dr. Williams

During the informative lecture titled, “Antibiotics Now: New Paradigms for Cefazolin, Vancomycin, and the Penicillin(PCN)-Allergic Patient,” by Richard J. Ing, MD, MB, BCh, FCA (SA) ( University of Colorado) the most recent information regarding the appropriate perioperative use of antibiotics was presented.  To begin, Dr. Ing discussed the importance of surgical site infection (SSI) prevention.  With approximately 22 percent of all nosocomial infections attributed to SSIs it is paramount that the anesthesiologist be well-informed on the correct choice and subsequent administration of antimicrobials.  There is also increased morbidity and mortality due to SSIs with an estimated cost of $1.6 billion  per year. 

As anesthesiologists we have the responsibility to ensure prompt and correct medication administration.  Based on the systematic review and meta-analysis data from de Jonge et al., Dr. Ing taught that the risk of SSI doubles when surgical antibiotic prophylaxis is given after first incision.  Additionally, SSI is five times higher  when the intravenous antibiotics are given greater than 120 minutes prior to incision. Thus, we can easily see that as perioperative physicians we play a crucial role in the overall prevention of SSIs.

Starting with the commonly administered antibiotics cefazolin and vancomycin, Dr. Ing provided great detail regarding their administration by focusing on three issues:

  • Bolus administration versus continuous infusion of cefazolin
  • Preoperative vancomycin administration
  • Evidence-based management of the PCN allergic patient

First, when considering the cephalosporin cefazolin, Dr. Ing reminded the audience of several key facts: it has excellent gram-positive skin flora coverage, and it does require that the drug exists in the unbound or free fraction form given it has time-dependent killing. 

Additionally, in 2011, Douglas et al. showed that a 2g bolus of cefazolin given 30 minutes prior to incision allows plasma and interstitial fluid (ISF) concentrations higher than the minimum inhibitory concentration (MIC) needed for susceptible pathogens.  Douglas and colleagues were able to see the inhibitory effects last for seven hours, thus making the argument for bolus administration.  When considering continuous cefazolin infusion, Dr. Ing referenced the 2016 article by Shoulders et al. that showed continuous infusion (CI) of cefazolin significantly decreased the incidence of  superficial SSI compared to intermittent (INT) cefazolin in patients who underwent coronary artery bypass grafting (CABG) surgery. 

The 2015 article by Trent Macgruder et al. showed that continuous infusion of cefazolin had a decline in the SSIs in patients who had CABG or cardiac valve procedures; however more randomized studies with much larger sample sizes remain necessary to create a formal conclusion as to whether CI leads to better outcomes than bolus administration.

When considering SSI prevention with preoperative vancomycin administration, vancomycin is certainly well-known for preventing SSIs caused by gram positive bacteria.  Its clinical longevity has also been shown to cause a variety of toxicities such as ototoxicity and nephrotoxicity, warranting evaluation of the pharmacokinetics of this commonly used antimicrobial. Subsequently, in 2012, Marsot and colleagues found dosage optimization for adults depends on creatine clearance and weight while the pediatric dose optimization depends on age, weight, and creatine clearance.

When it comes to caring for the PCN-allergic patient, one commonly posed question, “Is it safe for our PCN-allergic patient to receive cefazolin?” was discussed by Dr. Ing.  He briefly defined perioperative anaphylaxis as a severe, life-threatening hypersensitivity reaction.  According to The Sixth National Audit Project (NAP6) it is predicted that the anesthesiologist could potentially see a perioperative anaphylactic event approximately every seven years.  It also shows antibiotics to be the leading cause of perioperative events with an incidence of four out of 100,000 administrations, and approximately 50% of confirmed cases are due to antibiotics.  Given the desire to prevent anaphylaxis, anesthesiologists may be over-avoiding cefazolin unnecessarily. 

Additionally, some key concepts to  consider include:

  • The initial 10% cross reactivity of cephalosporins to PCNs is likely an overestimation due to previous cephalosporin contamination with mold
  • Over self-reporting of PCN allergies limits the choices in antibiotics needed to prevent SSIs
  • Second choice antibiotics can be less efficacious leading to increase incidence of SSIs
  • The perioperative physician must determine the extent of the allergic reaction to determine the risk for anaphylaxis
  • Tolerance of an oral penicillin-class antibiotic is the gold standard test for an absence of IgE-mediated penicillin allergy
  • The overall Cefazolin structure as well as an unrelated R sided chain to PCN cross reactivity quite unlikely. Cefazolin’s however, can cause its own type of allergic reaction
  • It is imperative that we are ready to treat hypersensitivity reactions appropriately with intravenous fluids and epinephrine

Overall, prevention of SSIs is crucial in reducing perioperative morbidity and mortality, and anesthesiologists must realize our vital role with perioperative antibiotic administration.  From choosing the correct drug and timing of administration, to understanding the potential for cross reactivity, to implementing the necessary treatment for hypersensitivity reactions, the anesthesiologist takes the lead in the fight against SSIs.

References:

OR Attire and Infection in 2019: What is the Evidence?

Scott Segal, MD, MHCM (Wake Forest Baptist Medical Center) gave an entertaining and excellent lecture titled, “OR Attire and Infection in 2019: What is the Evidence?".  It was a power-packed talk on the science behind the latest guidelines for operating room attire.  If you are an anesthesiologist you have heard of the Association of periOperative Registered Nurses (AORN).  This group is comprised thousands of nurses, whose main goal is advocating for excellence in the practice of perioperative medicine.

Dr. Segal began by introducing the 2017 edition of the “Recommendations for Infection Control for the Practice of Anesthesiology. Of note, it was mentioned that despite being developed by the Occupational Health Task Force it has not been reviewed or approved by the ASA House of Delegates; such approval is on the horizon.

When considering shoes and shoe covers, the AORN recommends having operating room-only shoes since it is possible for the bacteria on the floor to contribute to bacteria in the air by just walking around.  The AORN further concludes “shoes that are worn only in the perioperative area may help to reduce contamination of the perioperative environment.”  Dr. Segal did look at the literature and found that due to the constant mopping of floors in between cases, OR shoes are cleaner than outside shoes.  Additionally, one of the original articles cited by the AORN states that “redispersal of Staph. aureus from floor dust to air hardly increases the risk for airborne infection of operation wounds."  Another group, Humphrey et al.,  found that OR shoe covers did not necessarily decrease OR floor bacterial counts.  Thus, the case for shoe covers is less than stellar.

Moving to the great scrub debate, Dr. Segal discussed home laundered versus commercially laundered scrubs and the risk of SSIs.  Currently, there a few case reports of SSIs caused by home laundered scrubs.  There are no systematic studies showing SSIs to be associated with home laundered scrubs.  Furthermore, the Centers for Disease Control (CDC) has left the issue unresolved and has made no recommendation on the issue.  Overall there is seemingly no difference between commercially laundered scrubs and home laundered scrubs that are washed in high temperature water, then dried in high temperature tumble driers, and later ironed with a high temperature iron.

Regarding undershirts, the AORN recommends that no clothing extend beyond the scrubs, however, data for such a recommendation is lacking. 

When it comes to cover-ups or the white coat over scrubs, the data has shown cover apparel to have little or no effect on reducing contamination of surgical attire. Pertaining to the long-sleeved scrub jacket, the AORN initially recommended cover-ups, however data has shown that no cover-up is better at preventing contamination.  This can likely be attributed to the infrequent laundering of white coats compared to scrubs.  Thus, the AORN no longer recommends cover-ups for scrubs. 

The long sleeve jackets have been recommended by the AORN.  They suggest “all non-scrubbed personnel completely cover their arms with a long-sleeved scrub top or jacket.”  Of note the literature that was utilized to come to this conclusion did not evaluate long sleeve scrub tops. In fact, the study compared tucked scrubs versus untucked short sleeve cuffed scrubs.  There was a reduction in colony-forming units (CFUs), however again there was no evaluation of the garment in question.

Pertaining to the mask, the AORN recommends “a mask be worn in a manner that covers the nose and mouth to prevent surgical field contamination.”  However, actual evidence does not exist.  Both the AORN and ACS recommend no dangling masks while the ASA recommends a mask only when sterile items are open.  The AORN further recommends masks be changed whenever dirty, wet, or taken down; such a recommendation can also be quite costly to hospitals, increasing their cost by 5 – 10 times.  With the lack of evidence, such a cost may not be warranted.

The AORN recommends, “A clean surgical head cover or hood that confines all hair and completely covers the ears, scalp skin, sideburns and nape of the neck should be worn.”  Interestingly, a review in 2017 showed no conclusive evidence that wearing a head covering can help prevent surgical site infections.  Meanwhile, the AORN cites two case reports as the basis behind the guideline.  Additionally, a 2019 study by the ACS in found no difference in the SSI rate before and after implementation of the AORN head covering recommendations. 

Given the overall lack of strong evidence for OR attire there has been an effort to have a multidisciplinary approach and the AORN has met with the ACS, American Society of Anesthesiologists (ASA), Joint Commission and other stakeholders to discuss the evidence on surgical attire.  Despite the ongoing debate over OR attire, there is one area that appears to be of value in preventing SSIs – hand hygiene.  Thus, efforts to increase hand sanitizers and handwashing are of extreme importance.

Finally, with so many recommendations and restrictions, anesthesiologists could easily become disgruntled or even overwhelmed; but in lieu of feeling defeated, we are charged with the responsibility to not only check the evidence but to also do the work and construct studies in order to make certain that we are truly doing what’s best for the patient.

References:

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