Impact of Nasal Swabs on Empiric Treatment of Respiratory Tract Infections (INSERT-RTI)

Swab Testing to Optimize Pneumonia treatment with empiric Vancomycin (STOP-Vanc): study protocol for a randomized controlled trial

Background

Vancomycin, an antibiotic with activity against Methicillin-resistant Staphylococcus aureus (MRSA), is frequently included in empiric treatment for community-acquired pneumonia (CAP) despite the fact that MRSA is rarely implicated in CAP. Conducting polymerase chain reaction (PCR) testing on nasal swabs to identify the presence of MRSA colonization has been proposed as an antimicrobial stewardship intervention to reduce the use of vancomycin. Observational studies have shown reductions in vancomycin use after implementation of MRSA colonization testing, and this approach has been adopted by CAP guidelines. However, the ability of this intervention to safely reduce vancomycin use has yet to be tested in a randomized controlled trial.

Methods

STOP-Vanc is a pragmatic, prospective, single center, non-blinded randomized trial. Adult patients with suspicion for CAP who are receiving vancomycin and admitted to the Medical Intensive Care Unit at Vanderbilt University Medical Center will be screened for eligibility. Eligible patients will be enrolled and randomized in a 1:1 ratio to either receive MRSA nasal swab PCR testing in addition to usual care (intervention group), or usual care alone (control group). PCR testing results will be transmitted through the electronic health record to the treating clinicians. Primary providers of intervention group patients with negative swab results will also receive a page providing clinical guidance recommending discontinuation of vancomycin. The primary outcome will be vancomycin-free hours alive, defined as the number of hours alive and free of the use of vancomycin within the first seven days following trial enrollment estimated using a proportional odds ratio model. Secondary outcomes include 30-day all-cause mortality and time alive off vancomycin.

Discussion

STOP-Vanc will provide the first randomized controlled trial data regarding the use of MRSA nasal swab PCR testing to guide antibiotic de-escalation. This study will provide important information regarding the effect of MRSA PCR testing and antimicrobial stewardship guidance on clinical outcomes in an intensive care unit setting.

Trial registration

This trial was registered on ClinicalTrials.gov on February 22, 2024. (ClinicalTrials.gov identifier: NCT06272994).

Utility of Methicillin-Resistant Staphylococcus aureus Nasal PCR Testing in Pediatric Patients With Suspected Respiratory Infections

Observational studies in adults suggest nasal methicillin-resistant Staphylococcus aureus (MRSA) swabs have a high negative predictive value (NPV) for ruling out MRSA pneumonia, however, pediatric data are limited. This retrospective study of 505 pediatric patients found a 99.8% NPV among children with suspected respiratory infections.

Approaches to Reduce Use and Duration of Anti-MRSA Agents for Antimicrobial Stewardship Programs: A Review of Recent Literature

Antimicrobial stewardship programs (ASPs) have the potential to effectively deescalate unnecessary methicillin-resistant Staphylococcus aureus (MRSA) coverage. This review summarizes literature published from 2014 through 2021 describing contemporary ASP methods and their resulting effectiveness at reducing anti-MRSA agent use (ie vancomycin, linezolid, daptomycin, ceftaroline, and clindamycin). This review of the literature examined the following strategies, which had reports of success in either decreasing the use or duration of anti-MRSA agents: prospective review and feedback, antibiotic timeouts, health system or department protocol changes, polymerase chain reaction (PCR) and rapid testing of patient samples. Most of the current literature continue to support most ASP interventions including antibiotic timeouts, pathways, and molecular testing including MRSA nasal PCRs and rapid diagnostic testing can be successful at reducing unnecessary anti-MRSA use.

Duration of Gram-negative antibiotic therapy in patients with pneumonia prior to and after the implementation of MRSA nasal swabs, an antimicrobial stewardship tool

BACKGROUND

The implementation of MRSA PCR nasal swabs has been shown to decrease the use of anti-MRSA therapies through faster antibiotic de-escalation in patients with pneumonia. While this benefit has been shown exclusively in Gram-positive therapy, swab results may lead to additional antibiotic de-escalation discussions early on, potentially providing reduced durations or de-escalations of Gram-negative therapy as well.

OBJECTIVES

To determine if early de-escalation discussions prompted by MRSA swab results lead to shorter durations of Gram-negative antibiotic therapy.

METHODS

A retrospective chart review was conducted to compare pneumonia duration of Gram-negative therapy pre- and post-implementation of MRSA nasal swabs. Time to de-escalation, time to conversion to enteral therapy and cost were also compared between the groups.

RESULTS

Data were collected for 240 patients overall, 120 in each group. The median duration of Gram-negative therapy was 154.0 h in the post-implementation group and 176.4 h in the pre-implementation group (P = 0.002). There was no significant difference in time to de-escalation (52.7 versus 54.9 h; P = 0.351) or time to transition from IV to enteral therapy (53.0 versus 57.3 h; P = 0.289). The median cost of Gram-negative regimens per patient was less expensive in the post-implementation group ($31.36 versus $45.90; P = 0.002).

CONCLUSIONS

MRSA nasal swabs as an antimicrobial stewardship tool were associated with a reduced overall duration of Gram-negative therapy and Gram-negative antibiotic regimen cost. This introduces an additional benefit of MRSA nasal swabs and further incentivizes their use as an antimicrobial stewardship tool.