Each additional day of prophylactic antibiotic exposure after surgery can increase risk of adverse events, and it does not benefit infection prevention efforts, according to new research.1,2

“There’s benefit if you give antibiotics before surgery, but there’s no benefit if you give it after the surgery,” says Westyn Branch-Elliman, MD, MMSc, assistant professor of medicine at the VA Boston Healthcare System. Antimicrobials given in the absence of infection are risky after surgery. A study of 153,097 outpatient surgeries revealed that 7,712 received antimicrobial prophylaxis for more than 24 hours after surgery. Genitourinary surgeries, eye procedures, cystoscopies, and cystourethroscopies showed high rates of postsurgery antibiotic prophylaxis use.1

“There is no benefit for this practice in reducing surgery site infections, but there is a risk of harm every day,” Branch-Elliman says. “We’ve known for a long time that preoperative antibiotic prophylaxis is quite effective. “Pre-incision antibiotics prophylaxis clearly reduces rates of postoperative infections and improves care.”

The main benefit of presurgery antibiotics is that the drug can minimize contamination of the field, preventing bacteria from taking hold after the incision. But the benefits of antibiotic prophylaxis end when the surgery is over. “There’s been a lot of data [about] antibiotics after incision, and there’s no evidence it improves outcomes,” Branch-Elliman adds. “Some of the newer studies suggest that giving antibiotics for even a day or two after surgery increases risk of harm of other types of events, like acute kidney injuries.” Other antibiotic problems include rash and the promotion of antibiotic resistance.

For instance, another study revealed that when patients received a longer duration of antimicrobial prophylaxis, there were higher odds of Clostridioides difficile infection.2 “There could be bacteria living in the gut and waiting for an opening. When we give antibiotics and suppress healthy bacteria, it gives antimicrobial-resistant bacteria a chance to take over and cause infection,” Branch-Elliman explains.

Healthcare sites that follow guidelines from the Surgical Care Improvement Project (SCIP) discontinue prophylactic antibiotics after surgery. One SCIP measure, ABX 3, is to discontinue all antibiotics within 24 hours of surgery end time, unless there is provider documentation of infection or suspected infection.

“The VA was a good place to do this research because it has different recommendations,” Branch-Elliman says. “There are very clear guidelines and rankings for surgical centers, which allows us to gather some information about what ancillary services are available in those surgical centers.”

For example, more complex surgical patients were receiving evidence-driven care. This also should be the case with less complex cases, she adds. Investigators found that surgical subspecialties that had been influenced by SCIP’s guidelines were less likely to continue antibiotic prophylaxis after surgery. Their best practices were ingrained and integrated into clinical care.1

“Surgical specialties not covered by SCIP measures were more likely to prolong prophylaxis than those covered under SCIP,” Branch-Elliman says. The problem was that SCIP’s reach was limited and did not include all specialties when it was first developed by CMS and the CDC. “They discontinued the [ABX 3] measure, and it is no longer monitored by CMS,” Branch-Elliman says. “Our data were [collected] after the sunset date, and it demonstrated a change of practice among specialties that had been covered by the measure.”

The good news is that the recommended practice works, and surgical centers sustained the changes. “The bad news was it wasn’t used by all practice sites,” Branch-Elliman says.

Considering the strength of evidence showing that postsurgery antibiotic prophylaxis should be stopped, should someone promote this evidence-based practice among surgery centers that are not already following the SCIP guidelines?

“One way the VA has demonstrated an expansion of infection control is through a telemedicine program,” Branch-Ellison notes. The telemedicine program can be used for outreach to lower complexity facilities and to provide them with expert content in specific areas like how to prevent surgical site infections. “This is one way we can disseminate some of these findings to facilities that don’t have this infrastructure,” she says.


  1. Branch-Elliman W, et al. Facility type and surgical specialty are associated with suboptimal surgical antimicrobial, prophylaxis practice patterns: A multi-center, retrospective cohort study. Antimicrob Resist Infect Control 2019;8:49.
  2. Branch-Elliman W, et al. Association of duration and type of surgical prophylaxis with antimicrobial-associated adverse events. JAMA Surg 2019; Apr 24. doi: 10.1001/jamasurg.2019.0569. [Epub ahead of print].