Diabetic Foot Osteomyelitis Caused by Francisella Tularensis

Purpose: A rare patient case of a diabetic foot osteomyelitis caused by Francisella tularensis is presented. Summary: A 69-year-old Caucasian female was admitted for the treatment of diabetic foot osteomyelitis. Her past medical history included type II diabetes mellitus, hypertension, chronic kidney disease, coronary artery disease, hypothyroidism, hyperuricemia and thyroidectomy. Empiric antimicrobial therapy consisting of clindamycin 600mg i.v. every 8hrs and impanel/cilastatin 200 mg i.v. every 6hrs hours was initiated immediately after admission. During her hospitalization, a pus sample from the infection site was taken for culture which showed a gram negative microorganism: Francisella tularensis. The strain was resistant to all the antibiotics tested with the exception of ciprofloxacin, ofloxacin, gentamicin, ceftazidime, cefepime, piperacillin/tazobactam and colistin. After culture results, the treatment regimen was changed to piperacillin/tazobactam 4.5g i.v. every 12hrs and ciprofloxacin 400mg i.v. every 12hrs. The patient continued to receive both antibiotics during hospitalization for 9 days with noted clinical improvement. The patient was discharged on piperacillin/tazobactam 4.5g i.v. every 12hrs and oral ciprofloxacin 500mg every 12hrs to complete a total duration of 6 weeks. Conclusion: This is the first reported case of a diabetic foot osteomyelitis caused by Francisella tularensis.

Local Antibiotic Delivery Systems in Diabetic Foot Osteomyelitis: A Brief Review

Diabetic foot osteomyelitis (DFO) is a severe, difficult to treat infection. Local antibiotic delivery has been studied as a potential therapeutic adjunct following surgery for DFO. This review aims to summarize the evidence on local antibiotic delivery systems in DFO. PubMed database was searched up to March 2020. Overall, 16 studies were identified and included: 3 randomized controlled trials (RCTs), 3 retrospective studies (RSs), and 10 case series. In the RCTs, gentamicin-impregnated collagen sponges significantly improved clinical healing rates and slightly improved duration of hospitalization. In the RSs, antibiotic-impregnated calcium sulfate beads non-significantly improved all healing parameters, but did not reduce post-operative amputation rates or time of healing. The majority of case series used calcium sulfate beads, achieving adequate rates of healing and eradication of infection. In conclusion, evidence for add-on local antibiotic delivery in DFO is still limited; more data are needed to assess this therapeutic measure.

109. Evaluating Predictive Value of Surgical Resected Proximal Bone Margins in Diabetic Foot Osteomyelitis with Clinical Outcomes at One Year

Background Diabetic foot osteomyelitis (DFO) remains a significant comorbidity in diabetes and often requires both surgical and medical interventions. Surgical bone resection with proximal margins is performed for treatment at our institution to guide antimicrobial therapy. Optimal antibiotic duration often remains unclear, along with clinical outcomes with negative margins. We evaluate if negative bone margins predict outcomes of DFO at one year in our county hospital. Methods A retrospectively cohort study assessed adult patients undergoing DFO amputations between 9/2016 to 9/2019. Patient data collected included demographics, smoking history, hemoglobin A1c (HbA1c), basic labs, microbiology, antibiotic duration, bone margin pathology. Physician review of records determined if intervention was successful. Primary outcome was met if no further amputation at the same site was required in the following 12 months. Results Of 92 patients, 57 had negative margins and 35 had positive margins for pathology confirmed osteomyelitis. Smoking history was significant in positive margins (35.1% vs 57.1%; p=0.038). Patients with negative margins had a successful outcome at 12 months compared to positive margins (86% vs 66%; p=0.003), but no significant differences in outcome at 6 months. Antibiotic days was reduced in negative margin individuals (mean 18 vs 30 days; p=0.001). Negative margins also demonstrated significant lower rates of readmission at 12 months (p=0.015). Staphylococcus aureus was notable in positive vs negative margins (57.1% vs 29.8%; p=0.017). MSSA was significantly noted in positive margins (45.7% vs 14%; p=0.001). MRSA was similar regardless of margin results (15.8% vs 11.4%; p=0.399). Initial ESR, CRP and HbA1c were similar between groups. Conclusion Our study noted that negative proximal bone margins resulted in more successful outcomes at 12 months and less days of antimicrobial therapy. Patients with negative margins had lower rates of readmission at 12 months for surgical site complications. Negative proximal bone margins results can guide antibiotic therapy and improve outcomes of resections. Presence of S. aureus was significant in positive margins and likely warrant consideration for further aggressive intervention. Clinical Characteristics of Patients with Diabetic Foot Osteomyelitis Clinical demographics, antibiotic usage, microbiology and results of patients presenting for diabetic foot osteomyelitis needing surgical amputation intervention. Abbreviations: HbA1c - Hemoglobin A1c; MSSA - methicillin-susceptible Staphylococcus aureus; MRSA - methicillin-resistant Staphylococcus aureus; CRP -C-reactive protein; ESR - erythrocyte sedimentation rate Disclosures All Authors: No reported disclosures

Controversial Issues Regarding Positive Bone Margins in Surgery for Diabetic Foot Osteomyelitis: A Pilot Study

Obtaining clean margins in patients who undergo surgical treatment for diabetic foot osteomyelitis (DFO) is recommended. We hypothesize that the rate of recurrence of the infection is not associated with positive margins, even when using a short-term duration of postoperative antibiotic treatment. We conducted a retrospective pilot study of patients who underwent surgery for DFO confirmed by histopathological analysis of the resected bone from August 1, 2020, to December 1, 2020. Bone samples were taken from the proximal margins to be studied by microbiology and histopathology. Twenty-five (89.3%) patients underwent conservative surgery, and 3 (10.7%) patients underwent a minor amputation. After surgery, the antibiotics were stopped in 19 (67.9%) patients and continued in 9 (32.1%) patients for a median period of 4 days. The microbiology of the bone margins was positive in 20 (71.4%) cases, but the histopathology of the bone margins was positive in just 7 (25%) cases. Recurrence of the infection was detected in 3 (10.7%) patients. Seventeen (68%) patients with microbiological-positive margins did not have a recurrence of infection, while 3 (100%) patients had a recurrence of infection ( P = .53). Six (24%) patients among those with histopathological-positive margins did not have a recurrence of infection, and1 (33.3%) patient had a recurrence of infection ( P = 1). The recurrence of infection was low and always detected in soft tissues, including the cases with a histopathological-positive bone margin. Postoperative antibiotics were administered for a short period of time and not based on the analysis of bone margins.