Clinical and microbiological characteristics of skin and soft tissue infections of the extremities with bacteremia in patients with malignancy

Introduction: Although skin and soft tissue infections (SSTIs) of the extremities are primarily caused by Gram-positive cocci (GPC), some cases are caused by Gram-negative rod (GNR). In addition, malignancy is a recognized risk factor for GNR infection. Nevertheless, information on the clinical and microbiologic characteristics of SSTIs of the extremities caused by GNR in patients with malignancy is limited. Methods: Clinical and microbiological characteristics of patients with malignancy who developed bacteremic SSTIs of the extremities at a single cancer center over eight years were reviewed. In addition, whole-genome sequencing of the GNR isolates causing necrotizing fasciitis was conducted. Results: Of 42 cases identified, 32 cases (76.2 %) and 10 cases (23.8 %) were caused by GPC and GNR, respectively. Four cases in the GNR group were due to Escherichia coli, and the remaining cases were caused by diverse species. The majority of cases in the GNR group were hospital-onset and the lesions were limited to a single extremity. Chronic liver disease, cellular immunodeficiency, or anatomic abnormalities of the gastrointestinal, biliary, or urinary tract underlay seven GNR cases (70 %). Inappropriate empiric therapy was numerically more common in the GNR group compared to the GPC group (33.3 % vs. 9.4 %, p = 0.107). Whole-genome sequencing analysis revealed that two cases of GNR necrotizing fasciitis were caused by E. coli ST1193-fimH64 and Klebsiella pneumoniae K2-ST86. Conclusions: GNR organisms are a significant cause of SSTIs of the extremities in patients with malignancy and may be associated with inappropriate empiric therapy.