Implementation of a pre-surgical intervention that included screening for the bacteria Staphylococcus aureus, treating patients who were positive for this bacteria, and the administration of antibiotics based on these culture results was associated with a modest reduction in S. aureus surgical site infections (SSIs), according to a study in the June 2 issue of JAMA, The Journal of the American Medical Association.

S. aureus carriage increases the risk of S. aureus SSIs. The risk for these infections might be decreased by screening patients for nasal carriage of S. aureus and decolonizing carriers during the preoperative period. Perioperative prevention with agents such as the antibiotic vancomycin might reduce rates of methicillin-resistant S. aureus (MRSA) SSIs. Previous studies suggested that a bundled intervention was associated with lower rates of S. aureus SSIs among patients having cardiac or orthopedic operations, according to information in the article.

Loreen A. Herwaldt, MD, professor of internal medicine — infectious diseases at the University of Iowa Carver College of Medicine, Iowa City, and colleagues evaluated whether the implementation of an evidence-based bundle is associated with a lower risk of S. aureus SSIs in patients undergoing cardiac operations or hip or knee replacement or reconstruction. Twenty hospitals in nine U.S. states participated in this study. Rates of SSIs were collected for a median of 39 months during the pre-intervention period and a median of 21 months during the intervention period.

Patients whose preoperative nasal screens were positive for MRSA or methicillin-susceptible S. aureus (MSSA) were asked to apply the antibiotic mupirocin intranasally twice daily for up to five days and to bathe daily with chlorhexidine-gluconate (CHG), an antimicrobial agent, for up to five days before their operations. MRSA carriers received the antibiotics vancomycin and cefazolin or cefuroxime for perioperative prophylaxis. All others received cefazolin or cefuroxime. Patients who were MRSA-negative and MSSA-negative bathed with CHG the night before and morning of their operations. Patients were treated as MRSA-positive if screening results were unknown. (For more on this topic, see “Want to get a jump start on preventing infections? Have patients do the prep work,” Same-Day Surgery, March 2013.)

After a three-month phase-in period, bundle adherence remained constant at 83% (full adherence, 39%; partial adherence, 44%). The complex (deep incisional or organ space) S. aureus SSI rates decreased significantly among patients in the fully adherent group compared with the pre-intervention period, but rates did not decrease significantly in the partially adherent or nonadherent group.

Overall, 101 complex S. aureus SSIs occurred after 28,218 operations during the pre-intervention period and 29 occurred after 14,316 operations during the intervention period (average rate per 10,000 operations, 36 for pre-intervention period vs 21 for intervention period). The rates of complex S. aureus SSIs decreased for hip or knee arthroplasties (difference per 10,000 operations, -17) and for cardiac operations (difference per 10,000 operations, -6).

“Even though the baseline rate of complex S. aureus SSI was low (0.36 per 10,000 operations), the full adherence rate was only 39%, and hospitals had implemented some bundle elements before the study began, rates of complex S. aureus SSIs decreased significantly,” the researchers wrote. “Given that approximately 400,000 cardiac operations and one million total joint arthroplasties are performed in the United States each year, numerous S. aureus SSIs, which can have catastrophic consequences, may be preventable. Moreover, one SSI adds from $13,000 to $100,000 to the cost of health care. Thus, implementation of this bundle might reduce patient morbidity and the costs of care substantially.” (To access the abstract, go to http://bit.ly/1SW3zTi.)

Bundled approaches

In an accompanying editorial, Preeti N. Malani, MD, MSJ, professor of internal medicine at the University of Michigan Health System, Ann Arbor, and associate editor, JAMA, writes that although this study is a noteworthy addition to a growing body of high-quality infection prevention trials, many questions remain.

“Although S. aureus remains the principal pathogen in terms of prevalence and associated morbidity, many other organisms also cause SSIs. As such, decolonization of MSSA and MRSA can be only one aspect of SSI prevention. Although the current findings demonstrate a decrease in S. aureus SSIs, the authors did not find a decrease in gram-negative SSIs or complex SSIs caused by any pathogen. This finding might reflect the overall low rate of infection, but also is a poignant reminder that additional strategies still are needed.

“Public reporting and nonpayment for preventable complications (including some SSIs) have intensified efforts to eliminate infections — ‘to get to zero.’ The low-hanging fruit for SSI prevention has been picked and incremental decreases are unlikely to come from simple interventions. Although getting to zero is unlikely to be achievable, efforts that move closer to this elusive goal hold tremendous value for clinicians, hospitals, payers, and, most importantly, patients.” (To see the editorial, go to http://bit.ly/1IfCvvb.)