Clinical Outcomes of Antipseudomonal vs. Non-Antipseudomonal Therapy in Patients with Osteomyelitis

BACKGROUND: Osteomyelitis (OM) in diabetics is frequently a polymicrobial infection that rarely involves Pseudomonas (4–5% of cases). Bone cultures have a low-positive yield of 34–50% and, as a result, many patients receive antimicrobial regimens which include antipseudomonal (AP) therapy. METHODS: A retrospective cohort analysis of adult Veterans with OM treated with AP compared with non-antipseudomonal (NAP) therapy was conducted. Patients managed by the VA St. Louis outpatient parenteral antimicrobial therapy (OPAT) service from 1/1/2009 to 7/31/2015 were identified and screened for inclusion. Patients with culture negative (CN) or non-pseudomonal superficial swab cultures (SCx) were included. Figure 1 presents the study profile and exclusion criteria. The primary outcome was clinical failure, defined as a composite of: (1) extension of antibiotics beyond 1 week of the planned duration, (2) recurrence of OM at the same anatomical site within 12 months, or (3) any unplanned surgery or amputation at the anatomical site within 12 months of ABx completion. RESULTS: Overall, 104 patients with 109 OM encounters were included; there were 29 CN encounters and 80 SCx encounters. Table 1 presents baseline demographics. The overall failure rate was 55/109 (50.5%). The results of the analysis are shown in Table 2. While not included in the primary analysis, Pseudomonas was isolated from 8/88 (9.1%) swab cultures and 5/33 (15%) deep cultures. CONCLUSION: Empiric AP therapy did not improve clinical outcomes in patients with either CN or SCx OM. DISCLOSURES: All authors: No reported disclosures.