91. Microbiology of Vertebral Osteomyelitis and Implications on Empiric Therapy
Session: Oral Abstract Session: It's not just Bones: Skin and Bones
Thursday, October 5, 2017: 9:15 AM
Room: 01AB
Background: The management of vertebral osteomyelitis (VO) includes empiric antibiotic therapy while clinical cultures are being processed. Optimal antimicrobial therapy for VO, particularly when gram negative (GN) organisms are involved, is an area of ongoing debate. Narrow spectrum and oral antimicrobial therapy is preferred. The objective of this study is to identify characteristics of local pathogens and formulate an institution-specific antibiotic protocol for empiric treatment of VO.

Methods: We conducted a retrospective case series study of adults diagnosed with VO from 1 August 2010 to 31 August 2015 at Palmetto Health Hospitals in Columbia, SC. Cases identified by ICD-9 codes were included in the analysis if they met clinical, imaging and microbiology, criteria.

Results: Analysis is based on 150 cases of VO with a mean age of 61 years, a male predominance (91; 61%), and an average body mass index of 29 kg/m. Comorbidities included diabetes mellitus (69; 46%), tobacco use (33; 22%), and hemodialysis (20; 13%). Thirty-seven (25%) cases had recent related injury or vertebral surgery, and 14 (9%) had prior hardware. Bone, disc, or adjacent tissue cultures were obtained in 129 (86%) of cases; 60 (40%) of these had >1 sample taken. The remaining 14% had blood cultures alone. 36 cases (24%) had culture negative VO. In the remaining 114 cases, 132 organisms were isolated. 111 (84%) of organisms were gram-positive cocci (GPC). Of those, the majority were Staphylococcus aureus. (66; 59%) (26/66 were methicillin resistant), coagulase-negative staphylococci (20; 18%) and Streptococcus spp. (17; 15%). Enterobacteriaceae accounted for 13/17 gram-negative bacilli (GNB), with only 1 isolate of Pseudomonas aeruginosa. Of the GNB, 11/17 were susceptible to either ceftriaxone or ciprofloxacin.

Conclusion: There was a predominance of VO due to GPC suggesting that intravenous vancomycin monotherapy may be reasonable for empiric therapy in non-critically ill patients while awaiting Gram stain and clinical culture results. Addition of either ceftriaxone or ciprofloxacin to vancomycin would increase cumulative antimicrobial coverage from 84% to 92%.

Abbye Clark, BS1, Neha Sharma, BS1, Sharon Weissman, MD1, Majdi N. Al-Hasan, MBBS1, Caroline Derrick, PharmD, BCPS1 and Kamla Sanasi-Bhola, MD2, (1)University of South Carolina School of Medicine, Columbia, SC, (2)University of South Carolina, School of Medicine, Columbia, SC

Disclosures:

A. Clark, None

N. Sharma, None

S. Weissman, None

M. N. Al-Hasan, None

C. Derrick, None

K. Sanasi-Bhola, None

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