Nasal S. aureus colonization accounts for most postoperative staph infections
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Key takeaways:
- Most patients who developed an SSI or BSI had nasal colonization of S. aureus.
- Higher bacterial load added to the risk for postoperative infection.
Nasal colonization with Staphylococcus aureus accounted for most postoperative staph infections in a large cohort of adults who underwent surgery, according to a study published in Open Forum Infectious Diseases.
The researchers found that S. aureus (SA) colonization at any area of the body was a risk factor for surgical site infections (SSIs) and postoperative bloodstream infections (BSI) but said the evidence pointed to nasal carriage being the main culprit.
The finding that SA carriage anywhere on the body was associated with a higher risk for infection “was not surprising, as SA nasal carriage was highly prevalent within the carriers of our study,” the authors wrote, noting that patients colonized elsewhere on the body but not in the nose did not experience an increased risk.
According to the authors, SSIs develop in up to 20% of surgical patients and are associated with longer hospital stays and an up to 11-fold increase risk for death.
Universal screening programs and pathogen reduction, which can include chlorhexidine bathing and nasal application of mupirocin, have been shown to reduce infections and transmission.
Troeman and colleagues analyzed data from 5,004 patients who were treated at one of 33 hospitals in 10 European countries between December 2016 and September 2019 as part of the ASPIRE-SSI study, which was a prospective observational cohort study of adult surgical patients followed for up to 90 days after surgery to assess risk factors and occurrence of SA infections.
Among the study group, 3,369 patients (67.3%) were SA carriers. Out of those patients, 100 developed a staph SSI or BSI, 86% of whom were colonized with SA, according to the study.
The researchers found that the number of colonized bodily locations and an increasing bacterial load in the nose were associated with increased risk for either SSI or BSI.
Specifically, the risk was 3 1/2 times higher for patients colonized at one site (adjusted HR = 3.5; 95% CI, 1.7-7.2) and 8 1/2 times higher if they were colonized at three sites (aHR = 8.5; 95% CI, 2.2-33.8).
The risk was between 1.8 times higher (95% CI, 1-2.7) and 3.4 times higher (95%CI, 2.5-4.3) among people with “light” bacterial growth to “heavy” growth, according to the researchers.
Colonization outside the nose, however, was not independently associated with an increased risk for SSI or BSI (aHR = 1.5; 95% CI 0.9-2.5).
“Depending on the resources at hand, a ‘screen-and-treat’ strategy consisting of screening multiple bodily sites for SA colonization and then decolonizing the carriers could be a cost-effective strategy for preventing SA SSI,” the researchers concluded.
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