Prevalence of Recent Antimicrobial Exposure among Elective Surgical Patients

Tailored Pre-Operative Antibiotic Prophylaxis to Prevent Post-Operative Surgical Site Infections in General Surgery

The average American today undergoes three inpatient and two outpatient surgical procedures during one's life, each of which carries with it a risk of post-operative infection. It has long been known that post-operative infections cause significant morbidity in the immediate peri-operative period, but recent evidence suggests that they can have long-term consequences as well, increasing a patient's risk of infectious complications in unrelated surgeries performed months or even years later. While there are several theories on the origin of this association, including bacterial colonization of a post-operative infectious wound site, antimicrobial resistance from curative courses of antibiotics, subclinical immunosuppression, or the creation of an inflammatory "pathobiome" following an infectious insult, it is ultimately still unclear why patients who experience a single post-operative infection seem to be at a significantly higher risk of experiencing subsequent ones. Regardless, this association has significant implications for the routine use of pre-operative antibiotic prophylaxis. Indeed, while the prescription of antibiotics pre-operatively has dramatically reduced the rate of post-operative infections, the chosen prophylaxis regimens are typically standardized according to national guidelines, are facing increasing antimicrobial resistance patterns, and have been unable to reduce the risk of post-operative infection to acceptably low levels for certain surgeries. As a result, some clinicians have speculated that tailoring pre-operative antibiotic prophylaxis according to a patient's prior infectious and operative history could improve efficacy and further reduce the rate of post-operative infections. The purpose of this review is to describe the evidence for the link between multiple post-operative infections and explore the efficacy of individualized pre-operative prophylaxis.

Prior Antibiotic Exposure Is Associated With Reoperation After Elective Non-colorectal Surgery

BACKGROUND

Recent antibiotic exposure has previously been associated with poor outcomes following elective surgery. The purpose of this study is to evaluate the impact of prior recent antibiotic exposure in a multicenter cohort of Veterans Affairs patients undergoing elective non-colorectal surgery.

METHODS

This is a retrospective cohort study of the Veterans Affairs Surgical Quality Improvement Program, including elective, non-cardiovascular, non-colorectal surgery from 2013 to 2017. Outpatient antibiotic exposure within 90 days prior to surgery was identified from the Veterans Affairs outpatient pharmacy database and matched with each case. Primary outcomes included serious complication, any complication, any infection, or surgical site infection. Secondary outcomes included 30-day mortality, length of stay, and Clostridioides difficile infection.

RESULTS

Of 21,112 eligible patients, 2885 (13.7%) were exposed to antibiotics within 90 days prior to surgery with a duration of 7 (IQR: 5-10) days and prescribed 42 (IQR: 21-64) days prior to surgical intervention. Compared to non-exposed patients, exposed patients had higher unadjusted complication rates, increased length of stay, and rates of return to the operating. Exposure was independently associated with return to the operating room (OR: 1.39; 99% CI: 1.05-1.84).

CONCLUSIONS

Among Veterans, recent antibiotic exposure within 90 days of elective surgery was associated with a 39% increase in the odds of return to the operating room. Further work is needed to evaluate the effects of antibiotic exposure and dysbiosis on surgical outcomes.

Recent Anti-Microbial Exposure Is Associated with More Complications after Elective Surgery

BACKGROUND

Recent anti-microbial exposure has been associated with poor outcomes after infection in a mixed population. We hypothesized that recent anti-microbial exposure would be associated with poor outcomes of elective surgery.

METHODS

From August 2015 to August 2016, all elective surgical patients were questioned prospectively about anti-microbial exposure during the prior three months. Multivariable models were used to calculate risk-adjusted odds ratios for anti-microbial exposure controlling for surgeon influence. Primary outcomes were any serious complication, any complication, any infection, and surgical site infection. Secondary outcomes were length of stay, C. difficile infection, and death. A separate analysis of patients excluding those having colorectal surgery who had undergone an oral antibiotic bowel preparation also was performed.

RESULTS

Ninety-four percent of eligible patients (n = 1,538) answered the exposure question, with a three-month anti-microbial exposure rate of 34.1%. Colorectal surgery patients had the highest exposure rate, whereas hernia patients had the lowest. Exposed patients had higher rates of any complication, any infection, and surgical site infection, as well as a median two-day longer hospital stay. There were no differences in C. difficile infection or death between the groups. After risk adjustment, anti-microbial exposure was independently associated with any serious complication for all patients as well as with complications and infection in patients having an operation other than colorectal surgery.

CONCLUSION

Recent anti-microbial exposure is associated with more complications of elective surgery. Anti-microbial drug-induced alterations in microbiome-related inflammatory responses may play a role, highlighting an opportunity for pre-surgical intervention in this at-risk population.