Controversies in Perioperative Antimicrobial Prophylaxis

Brooke K. Decker, M.D.; Alexander Nagrebetsky, M.D.; Pamela A. Lipsett, M.D.; Jeanine P. Wiener-Kronish, M.D.; Naomi P. O'Grady, M.D.

Disclosures

Anesthesiology. 2020;132(3):586-597. 

In This Article

Microbiome-related Considerations

Human skin teems with an estimated 3.8 × 1013 microorganisms, more bacteria than human cells. Microorganisms from the skin and nasal passages are the most likely origin of surgical site infection in clean operations.[60] The human gut is likewise home to a diverse microbial community. In disease and injury, including elective surgery, the microbial density and metabolite production can change dramatically.[61,62] Numerous planned and unplanned interventions in the perioperative period directly influence the gut microbiota. For example, both enteral and parenteral antibiotics cause dysbiosis by killing commensal organisms. The loss of benefit from commensal pathogens can occur through several known mechanisms such as loss of competitive niche exclusion, antimicrobial inhibitory peptides, and intraspecies communication (quorum sensing). Reduction of the skin microbiome by application of skin antisepsis and nasal decolonization are primary strategies for reduction of surgical site infection.[60] In colonic surgery, mechanical bowel preparation alone has a significant impact on the microbiota aside from removal of bulk contents. One randomized trial evaluating the effect of mechanical bowel preparation on fecal microbiota demonstrated marked reduction in some species (Clostridium, Bifidobacteria, Lactobacillis, and Enterobacteriaceae), whereas they did not see any decrease in Enterococcus and Staphylococcus.[63] Importantly, mechanical bowel preparation also disrupts the mucosal layer of the colon, which can affect intracellular signaling and luminal pH. The use of antibiotics and critical illness in postoperative or injured surgical patients has shown a dramatic change in our microbiome, with a particular change in loss of microbial diversity.[64] Marked alterations in the microbiome have been identified in patients with a long length of stay in the hospital and in patients who had a planned pancreaticoduodenectomy. The microbiome in 50 patients studied preoperatively demonstrated that the microbiome of these patients were enriched with Klebsiella and Bacteroides and were depleted of anaerobic taxa. Further, patients with a postoperative pancreatic fistula contained increased Klebsiella and decreased commensal anaerobes.[65] Although we are far from understanding the specific role of the gut microbiome in healing of surgical anastomosis, there is active investigation into this area.[61]

Numerous studies have demonstrated increased risk of postoperative infection in a vast array of surgical patients who are colonized with resistant pathogens such as methicillin-resistant S. aureus, extended spectrum β-lactamase producers, and carbapenemase-resistant Enterobacteriaceae.[66] Because of this known increased risk, it may be reasonable to alter preoperative preparation, especially for S. aureus, using strategies that may include preoperative screening and surface decontamination (mupirocin).[67] The decision to adjust perioperative antibiotic prophylaxis to cover known resistant species should take into account the procedure and reservoir of the resistant pathogen.[8,68,69]

Methicillin-resistant S. aureus

Several studies in cardiothoracic, gastrointestinal, and orthopedic procedures have demonstrated a correlation between colonization with S. aureus and the development of surgical site infection.[42] Guidelines produced by the American College of Surgeons (Chicago, Illinois) and the Surgical Infection Society (East Northport, New York) in 2017 identified this problem and noted that screening and decolonization should depend on baseline surgical site infection and methicillin-resistant S. aureus rates.[70] Guidelines from the American Society of Health System Pharmacists (Bethesda, Maryland) recommend screening and decolonization for all patients colonized with S. aureus before total joint replacement and cardiac procedures.[8] Methicillin-resistant S. aureus bundles (screening, decolonization, contact precautions, and hand hygiene) are noted to be highly effective when all components are implemented. The guidelines further note that there is no specific standard decolonization strategy supported by the literature; nasal mupirocin has been used alone and in combination with chlorhexidine gluconate bathing. Povidone–iodine solutions have also being used to decolonize the anterior nares.[71] These methods should be performed close to the time of surgery to be effective, ideally within 3 months.[72]

The threat of postoperative methicillin-resistant S. aureus infection has caused some providers to prescribe vancomycin and vancomycin plus a β-lactam for prophylaxis for a wide variety of procedures. In a review of more than 70,000 procedures matched by propensity scoring, vancomycin prophylaxis had a clear benefit for reduction of surgical site infection (in cardiac surgery only) but was associated with unintended harm, namely an increase in acute kidney injury across all populations studied. Screening and directed prophylaxis may maximize benefits while minimizing harm. When prescribed for methicillin-resistant S. aureus colonization, vancomycin as well as standard prophylaxis (e.g., cefazolin) should be administered in combination.[8] Finally, vancomycin should not be administered as prophylaxis to methicillin-resistant S. aureus–negative patients.[25,70]

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