1. Pathogens resistant to standard prophylactic antibiotics caused from over one-third to one-half of infections associated with the ten most common surgical procedures and over one-quarter of infections after cancer chemotherapy.
2. A 30% reduction in antibiotic efficacy due to resistance was estimated to cause 120,000 more infections per year in the USA and over 6,000 more infection-related deaths per year.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Antibiotics are commonly given prophylactically for surgery and cancer chemotherapy in order to prevent infection. However, the rise of bacterial resistance to antibiotics may cause complications such as increased rates of infection, amputation, or death. This study investigated the potential consequences of increasing antibiotic resistance on the ten most common surgical procedures and cancer chemotherapies in the USA that rely on prophylactic antibiotic treatment. Meta-analyses of randomized controlled trials were analyzed and the results applied to estimate the efficacy of antibiotic prophylaxis in preventing infections and deaths related to infections from these surgical procedures and chemotherapy treatments. Varying scenarios of reduced antibiotic efficacy (10%, 30%, 70%, and 100% reductions) were then applied to estimate the additional number of infections and deaths per year. Finally, this study estimated the percentage of infections caused by pathogens resistant to standard prophylactic antibiotics after these procedures.
The results showed that over one-third to one-half of infections associated with surgery and more than one-quarter of infections after chemotherapy were caused by pathogens resistant to standard prophylactic antibiotics. A 30% reduction in antibiotic efficacy was estimated to cause 120,000 more infections per year in the USA and over 6,000 more infection-related deaths per year. Strengths of this study included the large number of meta-analyses and randomized controlled trials included in this study, while limitations included that trials included in the meta-analyses were conducted over a long time period, in which results may not be as applicable with newer, modern infection control measures.
Click to read the study in The Lancet Infectious Diseases
Relevant Reading: Clinical practice guidelines for antimicrobial prophylaxis in surgery
In-Depth [meta-analysis]: 31 meta-analyses of 290 randomized controlled trials or quasi-randomized controlled trials from 1968 to 2011 were identified for this study. The annual numbers of surgeries in the USA were obtained from the 2010 CDC National Hospital Discharge Survey, and the annual number of chemotherapy treatments for leukemia, lymphoma, and myeloma were estimated from the National Cancer Database. The ten most common surgical procedures and cancer chemotherapies included in this study were hip fracture surgery, pacemaker implantation, surgical abortion, spinal surgery, total hip replacement, caesarean section, transrectal prostate biopsy, appendectomy, abdominal hysterectomy, and colorectal surgery. Common antibiotic prophylaxis for those procedures included cefazolin, fluoroquinolones, and metronidazole.
The overall surgical site infection rate for patients in the meta-analyses was 4.2% for those that received prophylactic antibiotics, compared to 11.1% for those that did not. The relative risk reduction (RRR) of infection with prophylactic antibiotics ranged from 35% for cancer chemotherapy up to 86% for pacemaker implantation. Surgical site infections caused by antibiotic resistant pathogens ranged from 38.7% with caesarean section to 50.9% with transrectal prostate biopsy. 26.8% of infections were caused by resistant organisms after cancer chemotherapy. A 30% reduction in antibiotic efficacy was estimated to cause 120,000 more infections per year in the USA for the ten most common surgical procedures plus chemotherapy treatments, and ranged from 40,000 more per year for a 10% reduction up to 280,000 per year for a 70% reduction in efficacy. Additionally, a 30% reduction in efficacy was estimated to cause 6,367 more infection-related deaths per year (range 2,100 deaths for 10% reduction, 15,000 deaths for a 70% reduction), with most occurring for patients undergoing colorectal surgery (4,586 deaths), blood cancer chemotherapy (683 deaths), and total hip replacement (376 deaths).
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