Failure to De-escalate Empirical Vancomycin

Empirical antimicrobial treatment in acute care settings is often the result of the “diagnosis momentum” heuristic, wherein the antibiotics started in one location for “sepsis” are continued for several additional days after transfer to another location. Vancomycin remains one of the most commonly prescribed inpatient antibiotics, despite a decline in the prevalence of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections. Two recent studies highlight the infrequent isolation of MRSA in patients receiving empirical vancomycin and diagnostic stewardship interventions to promote vancomycin de-escalation.

Waters and colleagues^[1] compared the rate of vancomycin use with subsequent positive cultures justifying treatment with vancomycin in a single-center retrospective observational study. Most of these infections were skin and soft-tissue infections, bacteremia, and pneumonia.

Concern about MRSA is probably the main driver of vancomycin use, yet this organism was confirmed in only 8.4% of the positive cultures. During the 3-month study, only 11% of 1662 patients on vancomycin had a positive culture necessitating vancomycin use as definitive therapy.

Empirical vancomycin can probably be safely de-escalated in nearly 90% of patients, especially after 48 hours of negative cultures. However, convincing prescribers to discontinue antibiotics presents a separate challenge for antimicrobial stewardship programs.

A Nudge Toward De-escalation

Musgrove and colleagues^[2] capitalized on the fact that most decisions to start empirical vancomycin and piperacillin-tazobactam for pneumonia occur in the context of concern about unidentified MRSA or Pseudomonas aeruginosa. They performed a quasi-experimental study within a four-hospital system in Detroit to evaluate the impact of a modification to respiratory culture reports on antibiotic use. The microbiology lab changed the way in which they report normal “commensal respiratory flora” (which includes Neisseria, Corynebacterium, and Streptococcus, with no dominant growth of any single organism) to clinicians. They added the statement “No S aureus/MRSA or P aeruginosa” to the report, and the antibiotic stewardship program provided a brief education to prescribers.

After this behavioral nudge was implemented, prescribers were 34% (P < .01), or 5.5-fold, more likely to de-escalate antibiotics. Furthermore, with fewer vancomycin/piperacillin-tazobactam combination days of therapy, they noted a 17% reduction in acute kidney injury (P < .03) even after adjustment for severity of illness. The days of therapy for MRSA and Pseudomonas were reduced from 7 to 5 days (P < .01). The investigators observed additional opportunity for de-escalation, because intervention patients still received a median of 5 days of anti-MRSA and anti-pseudomonal therapy.

Multidrug-resistant organisms (MDROs) were not prevalent in either group; however, there was a significant reduction in development of subsequent MDROs after the culture result nudge (8% vs 1%; P =.035). There was no effect on mortality or development of Clostridium difficile infection, or change in length of intensive care unit or hospital length of stay.

Viewpoint

Behavioral nudges, which use positive reinforcement and indirect messaging to influence decision-making, already exist in many areas of our clinical environment. This study highlights the importance of clear communication of microbiology results as a means to influence antibiotic use. As antibiotic stewardship programs aim to collaborate with prescribers to change behaviors, these behavioral nudges can be useful low-effort/high-yield tools to further assist with antibiotic de-escalation.