Conclusions
Only half of the MDR/XDR GNB OAI cases treated by antimicrobials and surgery had a successful outcome. Advanced age and multiple surgeries hampered the eradication of OAI. Optimal therapeutic options remain a challenge.
Methods
A prospective multicentre observational study was conducted on behalf of ESGIAI (the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group on Implant-Associated Infections). Factors associated with remission of the infection were evaluated by multivariate and Cox regression analysis for a 24-month follow-up period.
Purpose
The purpose of this study was the clinical and therapeutic assessment of lower-limb osteosynthesis-associated infection (OAI) by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacteria (GNB), which have been poorly studied to date.
Results
Patients ( n = 57 <math><mrow><mi>n</mi> <mo>=</mo> <mn>57</mn></mrow> </math> ) had a history of trauma (87.7 %), tumour resection (7 %) and other bone lesions (5.3 %). Pathogens included Escherichia coli ( n = 16 <math><mrow><mi>n</mi> <mo>=</mo> <mn>16</mn></mrow> </math> ), Pseudomonas aeruginosa ( n = 14 <math><mrow><mi>n</mi> <mo>=</mo> <mn>14</mn></mrow> </math> ; XDR 50 %), Klebsiella spp. ( n = 7 <math><mrow><mi>n</mi> <mo>=</mo> <mn>7</mn></mrow> </math> ), Enterobacter spp. ( n = 9 <math><mrow><mi>n</mi> <mo>=</mo> <mn>9</mn></mrow> </math> ), Acinetobacter spp. ( n = 5 <math><mrow><mi>n</mi> <mo>=</mo> <mn>5</mn></mrow> </math> ), Proteus mirabilis ( n = 3 <math><mrow><mi>n</mi> <mo>=</mo> <mn>3</mn></mrow> </math> ), Serratia marcescens ( n = 2 <math><mrow><mi>n</mi> <mo>=</mo> <mn>2</mn></mrow> </math> ) and Stenotrophomonas maltophilia ( n = 1 <math><mrow><mi>n</mi> <mo>=</mo> <mn>1</mn></mrow> </math> ). The prevalence of ESBL (extended-spectrum β<math><mi>β</mi></math> -lactamase), fluoroquinolone and carbapenem resistance were 71.9 %, 59.6 % and 17.5 % respectively. Most patients ( n = 37 <math><mrow><mi>n</mi> <mo>=</mo> <mn>37</mn></mrow> </math> ; 64.9 %) were treated with a combination including carbapenems ( n = 32 <math><mrow><mi>n</mi> <mo>=</mo> <mn>32</mn></mrow> </math> ) and colistin ( n = 11 <math><mrow><mi>n</mi> <mo>=</mo> <mn>11</mn></mrow> </math> ) for a mean of 63.3 d. Implant retention with debridement occurred in early OAI (66.7 %), whereas the infected device was removed in late OAI (70.4 %) ( p = 0.008 <math><mrow><mi>p</mi> <mo>=</mo> <mn>0.008</mn></mrow> </math> ). OAI remission was achieved in 29 cases (50.9 %). The type of surgery, antimicrobial resistance and duration of treatment did not significantly influence the outcome. Independent predictors of the failure to eradicate OAI were age > 60 <math><mrow><mo>></mo> <mn>60</mn></mrow> </math> years (hazard ratio, HR, of 3.875; 95 % confidence interval, CI95 %, of 1.540-9.752; p = 0.004 <math><mrow><mi>p</mi> <mo>=</mo> <mn>0.004</mn></mrow> </math> ) and multiple surgeries for OAI (HR of 2.822; CI95 % of 1.144-6.963; p = 0.024 <math><mrow><mi>p</mi> <mo>=</mo> <mn>0.024</mn></mrow> </math> ). Conclusions: Only half of the MDR/XDR GNB OAI cases treated by antimicrobials and surgery had a successful outcome. Advanced age and multiple surgeries hampered the eradication of OAI. Optimal therapeutic options remain a challenge.