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.