By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

SOURCE: Teillant A, Gandra S, Morgan DJ, et al. Potential burden of antibiotic resistance on surgery and cancer chemotherapy antibiotic prophylaxis in the USA: A literature review and modelling study. Lancet Infect Dis 2015;15;1429-1437.

This interesting article from Teillant and colleagues (who is now doing some interesting work at the Center for Disease Dynamics, Economics, and Policy in Washington, DC) highlights the threat of antibacterial resistance not only to our ability to fight active infection, but to prevent surgical site infection (SSI) using perioperative antibacterials. For example, it is estimated that 157,500 surgical site infections, resulting in 3% mortality, occurred in the United States in 2011. In addition, at least 65,000 cancer patients required hospitalization for infection complicating chemotherapy treatments. For the 10 most common surgical procedures in the United States, the use of perioperative antibiotics is estimated to reduce the relative risk of infection anywhere from 35% to 86%, depending on the procedure. However, the increasing prevalence of antibacterial resistance threatens this success. For example, in patients undergoing transrectal prostate biopsy, who received prophylactic fluoroquinolone (FQ) treatment, infection rates were 8.2% in those with rectal cultures positive for FQ-resistance, but only 1.8% in those without FQ resistance. Obviously, increasing rates of FQ resistance in rectal cultures, currently estimated at about 20%, will diminish the effectiveness of FQs for prophylaxis in these cases.

Using 31 different meta-analyses, as well as randomized clinical trails and quasi-randomized, clinical trials that met their criteria, investigators examined the effectiveness of perioperative antibiotic therapy in SSIs and surgical-infection-related deaths for 10 common surgical procedures performed in the United States, as well as the risk of hospitalization and death in cancer chemotherapy patients. In the summary meta-analysis, the overall SSI rate for patients receiving perioperative antibacterials was 4.2% compared with 11.1% for patients not receiving perioperative antibiotics. They estimated the rates of resistance to standard perioperative antibacterials, in those procedures complicated by infection, currently range from 38.7% for cesarean and hysterectomy to 50% in men undergoing trans-rectal prostatic biopsy. For spine surgery, total hip replacement, and hip fracture surgery complicated by infection, 48% of those infections exhibit resistance to standard perioperative antibacterials. And 27% of cancer patients have pathogens isolated with resistance to commonly used antibiotics.

The researchers then structured a complex mathematical model for different scenarios of reduced antibacterial effectiveness by 10%, 30%, 70%, or 100%. A reduction of only 10% in the current antibacterial efficacy would result in an estimated 40,000 additional SSIs and chemotherapy-related infections and 2,100 deaths. A reduction of 70% in antibacterial efficacy would result in an additional 280,000 SSIs and chemotherapy-related infections and 15,000 deaths. Most of the additional deaths would be for colorectal procedures, total hip replacement, and chemotherapy for hematologic malignancy.

To combat this trend in reduced antibacterial efficacy, strategies to identify patients at higher risk for infection have been proposed, such as pre-operative screening for nasal colonization for methicillin-resistant Staphylococcus aureus, especially in those undergoing surgical procedures with hardware. But these strategies are limited by sampling error, the limited effectiveness of decolonization strategies, not to mention the difficulty in getting surgeons to adopt this as a routine practice. This is one reason hospitals are moving toward pre-operative measures such as chlorhexidine scrubs and “nose-to-toes” pre-operative programs — which ultimately may prove the more cost-effective and safer route to prevent SSIs.