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Background Optimal timing of bone culture obtainment relative to antibiotic initiation in diabetic foot osteomyelitis is unknown. This study aims to determine whether antibiotic administration prior to bone sample collection affects microbiological yield. Methods This was a single-center retrospective study. Patients at least 18 years old admitted for diabetic foot osteomyelitis management were included. Patients included in the study had an evaluable bone sample and met the following criteria: presence of imaging demonstrating osteomyelitis, documentation of wound probing to bone, or visible bone in wound; plus an elevated erythrocyte sedimentation rate or elevated C-reactive protein. Patients included also received at least one dose of antibiotics during the hospitalization. Patients with necrotizing fasciitis and those who left against medical advice were excluded. Results One hundred and fifteen patients were included; 78 received antibiotics prior to bone sample obtainment (prior group), and 37 received antibiotics post sample obtainment (post group). Average time from admission to bone sample obtainment in the prior group was 1.8 ± 2.1 days and 1.1 ± 1.0 days in the post group. There was a non-significant difference in microbiological yields between the two groups (78.2% vs 75.7%, p = 0.762). Further examining the prior group, the average time between the antibiotic initiation and bone sample obtainment was not significantly different between those who had microbiological growth versus those who did not (2 ± 1.4 versus 1.6 ± 2.3 days [p = 0.0942]). Logistic regression analysis did not show association of microbiological yield with any of the following variables: peripheral vascular disease, end-stage renal disease, biopsy type (bedside vs open), type of osteomyelitis (acute vs chronic vs acute-on-chronic), antibiotic use prior to admission, or types of antibiotics administered. Conclusion Our data suggests that approximately two days of antibiotics prior to bone biopsy does not affect microbiological yield on cultures. Bone samples were obtained expeditiously within our cohort, which may account for the lack of difference seen. Further studies are needed to better define the duration of antibiotic therapy at which a difference in bone culture yields will be expected. Disclosures Asia N. Quan, PharmD, BCPS, BCCCP, Shionogi: Honoraria|Trevena: Honoraria Carlos Hartmann, MD, Viiv Pharmaceuticals: Speaker.

Background Hepatitis B virus (HBV) vaccine seroprotection rates with conventional aluminum adjuvanted recombinant HBV vaccines (HepB-alum) among people with HIV (PWH) are varied. HepB-CpG, a novel adjuvanted recombinant HBV vaccine, has shown higher seroprotection rates in immunocompetent patients but is not well studied in PWH. There are no published studies comparing seroprotection rates between HepB-alum and HepB-CpG in PWH. The purpose of this study was to evaluate and compare the seroprotection incidence of HepB-CpG versus HepB-alum in adults at least 18 years of age with HIV. Methods This retrospective, observational, cohort study screened for inclusion adults diagnosed with HIV who received a 3-dose series of HepB-alum or a 2-dose series of HepB-CpG between January 1, 2015 through December 31, 2021 at a community health center in Phoenix, Arizona. Patients who had a confirmed diagnosis of HIV and a hepatitis B surface antibody < 10 IU/L at the time of the first vaccine dose were included until an adequate sample size was achieved. The primary outcome was to compare seroconversion incidence of HepB-CpG and HepB-alum in PWH. Secondary outcomes included identifying factors associated with an increased likelihood of response to HBV vaccination. Seroconversion incidence data was analyzed using Fisher’s exact test using BlueSky Statistics. Results A total of 121 patients were included in this study, 59 in the HepB-alum cohort and 61 in the HepB-CpG cohort. In the HepB-alum cohort, 57.6% (34/59) achieved seroconversion, compared to 93.4% (57/61) in the HepB-CpG group (p < 0.001). Univariate comparisons of comorbidities among the vaccine cohorts found no significant differences in sex, body mass index, diabetic status, kidney/liver disease, CD4 count, HIV viral load, or active/prior history of substance use. Conclusion Among PWH at a single community health center, HepB-CpG provided a statistically higher incidence of seroprotection against HBV compared to HepB-alum. The higher seroprotection rate for HepB-CpG versus HepB-alum patients is not due to differences in group demographics or reported comorbidities. Disclosures Carlos Hartmann, MD, Viiv Pharmaceuticals: Speaker.